Internet DRAFT - draft-ietf-l2vpn-evpn
draft-ietf-l2vpn-evpn
Network Working Group A. Sajassi, Ed.
INTERNET-DRAFT Cisco
Category: Standards Track
R. Aggarwal
J. Drake Arktan
Juniper Networks
N. Bitar
W. Henderickx Verizon
Alcatel-Lucent
Aldrin Isaac
Bloomberg
J. Uttaro
AT&T
Expires: April 18, 2015 October 18, 2014
BGP MPLS Based Ethernet VPN
draft-ietf-l2vpn-evpn-11
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document authors. All rights reserved.
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Abstract
This document describes procedures for BGP MPLS based Ethernet VPNs
(EVPN). The procedures described here meet the requirements specified
in RFC7209 - Requirements for Ethernet VPN.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Specification of requirements . . . . . . . . . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. BGP MPLS Based EVPN Overview . . . . . . . . . . . . . . . . . 6
5. Ethernet Segment . . . . . . . . . . . . . . . . . . . . . . . 7
6. Ethernet Tag ID . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1 VLAN Based Service Interface . . . . . . . . . . . . . . . . 11
6.2 VLAN Bundle Service Interface . . . . . . . . . . . . . . . 11
6.2.1 Port Based Service Interface . . . . . . . . . . . . . . 11
6.3 VLAN Aware Bundle Service Interface . . . . . . . . . . . . 11
6.3.1 Port Based VLAN Aware Service Interface . . . . . . . . 12
7. BGP EVPN Routes . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Ethernet Auto-Discovery Route . . . . . . . . . . . . . . . 13
7.2. MAC/IP Advertisement Route . . . . . . . . . . . . . . . . 13
7.3. Inclusive Multicast Ethernet Tag Route . . . . . . . . . . 14
7.4 Ethernet Segment Route . . . . . . . . . . . . . . . . . . . 15
7.5 ESI Label Extended Community . . . . . . . . . . . . . . . . 15
7.6 ES-Import Route Target . . . . . . . . . . . . . . . . . . . 16
7.7 MAC Mobility Extended Community . . . . . . . . . . . . . . 16
7.8 Default Gateway Extended Community . . . . . . . . . . . . . 17
7.9 Route Distinguisher Assignment per EVI . . . . . . . . . . . 17
7.10 Route Targets . . . . . . . . . . . . . . . . . . . . . . . 17
7.10.1 Auto-Derivation from the Ethernet Tag ID . . . . . . . 17
8. Multi-homing Functions . . . . . . . . . . . . . . . . . . . . 18
8.1 Multi-homed Ethernet Segment Auto-Discovery . . . . . . . . 18
8.1.1 Constructing the Ethernet Segment Route . . . . . . . . 18
8.2 Fast Convergence . . . . . . . . . . . . . . . . . . . . . . 18
8.2.1 Constructing Ethernet A-D per Ethernet Segment Route . . 19
8.2.1.1. Ethernet A-D Route Targets . . . . . . . . . . . . 20
8.3 Split Horizon . . . . . . . . . . . . . . . . . . . . . . . 20
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8.3.1 ESI Label Assignment . . . . . . . . . . . . . . . . . . 21
8.3.1.1 Ingress Replication . . . . . . . . . . . . . . . . 21
8.3.1.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . 22
8.4 Aliasing and Backup-Path . . . . . . . . . . . . . . . . . . 23
8.4.1 Constructing Ethernet A-D per EVPN Instance Route . . . 24
8.5 Designated Forwarder Election . . . . . . . . . . . . . . . 25
8.6. Interoperability with Single-homing PEs . . . . . . . . . . 27
9. Determining Reachability to Unicast MAC Addresses . . . . . . . 27
9.1. Local Learning . . . . . . . . . . . . . . . . . . . . . . 28
9.2. Remote learning . . . . . . . . . . . . . . . . . . . . . . 28
9.2.1. Constructing MAC/IP Address Advertisement . . . . . . . 28
9.2.2 Route Resolution . . . . . . . . . . . . . . . . . . . . 30
10. ARP and ND . . . . . . . . . . . . . . . . . . . . . . . . . . 31
10.1 Default Gateway . . . . . . . . . . . . . . . . . . . . . . 32
11. Handling of Multi-Destination Traffic . . . . . . . . . . . . 33
11.1. Constructing Inclusive Multicast Ethernet Tag Route . . . 34
11.2. P-Tunnel Identification . . . . . . . . . . . . . . . . . 34
12. Processing of Unknown Unicast Packets . . . . . . . . . . . . 35
12.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 36
12.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . . . . . 36
13. Forwarding Unicast Packets . . . . . . . . . . . . . . . . . . 37
13.1. Forwarding packets received from a CE . . . . . . . . . . 37
13.2. Forwarding packets received from a remote PE . . . . . . . 38
13.2.1. Unknown Unicast Forwarding . . . . . . . . . . . . . . 38
13.2.2. Known Unicast Forwarding . . . . . . . . . . . . . . . 38
14. Load Balancing of Unicast Frames . . . . . . . . . . . . . . . 38
14.1. Load balancing of traffic from a PE to remote CEs . . . . 39
14.1.1 Single-Active Redundancy Mode . . . . . . . . . . . . . 39
14.1.2 All-Active Redundancy Mode . . . . . . . . . . . . . . 39
14.2. Load balancing of traffic between a PE and a local CE . . 41
14.2.1. Data plane learning . . . . . . . . . . . . . . . . . 41
14.2.2. Control plane learning . . . . . . . . . . . . . . . . 41
15. MAC Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 42
15.1. MAC Duplication Issue . . . . . . . . . . . . . . . . . . 43
15.2. Sticky MAC addresses . . . . . . . . . . . . . . . . . . . 44
16. Multicast & Broadcast . . . . . . . . . . . . . . . . . . . . 44
16.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 44
16.2. P2MP LSPs . . . . . . . . . . . . . . . . . . . . . . . . 44
16.2.1. Inclusive Trees . . . . . . . . . . . . . . . . . . . 45
17. Convergence . . . . . . . . . . . . . . . . . . . . . . . . . 45
17.1. Transit Link and Node Failures between PEs . . . . . . . . 45
17.2. PE Failures . . . . . . . . . . . . . . . . . . . . . . . 46
17.3. PE to CE Network Failures . . . . . . . . . . . . . . . . 46
18. Frame Ordering . . . . . . . . . . . . . . . . . . . . . . . . 46
19. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 47
20. Security Considerations . . . . . . . . . . . . . . . . . . . 47
21. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 49
22. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49
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23. References . . . . . . . . . . . . . . . . . . . . . . . . . . 50
23.1 Normative References . . . . . . . . . . . . . . . . . . . 50
23.2 Informative References . . . . . . . . . . . . . . . . . . 50
24. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 51
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1. Introduction
This document describes procedures for BGP MPLS based Ethernet VPNs
(EVPN). The procedures described here meet the requirements specified
in [RFC7209]. Please refer to [RFC7209] for the detailed
requirements and motivation. EVPN requires extensions to existing
IP/MPLS protocols as described in this document. In addition to these
extensions EVPN uses several building blocks from existing MPLS
technologies.
2. Specification of requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Terminology
Broadcast Domain: In a bridged network, it corresponds to a Virtual
LAN (VLAN); where a VLAN is typically represented by a single VLAN ID
(VID), but can be represented by several VIDs where Shared VLAN
Learning (SVL) is used per [802.1Q].
Bridge Domain: An instantiation of a broadcast domain on a bridge
node
CE: Customer Edge device e.g., host or router or switch
EVI: An EVPN instance spanning across the PEs participating in that
EVPN
MAC-VRF: A Virtual Routing and Forwarding table for MAC addresses on
a PE for an EVI
Ethernet Segment (ES): If a multi-homed device or network is
connected to two or more PEs via a set of Ethernet links, then that
set of links is referred to as an 'Ethernet segment'.
Ethernet Segment Identifier (ESI): A unique non-zero identifier that
identifies an Ethernet Segment is called an 'Ethernet Segment
Identifier'.
Ethernet Tag: An Ethernet Tag identifies a particular broadcast
domain, e.g., a VLAN. An EVPN instance consists of one or more
broadcast domains. Ethernet tag(s) are assigned to the broadcast
domains of a given EVPN instance by the provider of that EVPN, and
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each PE in that EVPN instance performs a mapping between broadcast
domain identifier(s) understood by each of its attached CEs and the
corresponding Ethernet tag.
LACP: Link Aggregation Control Protocol
MP2MP: Multipoint to Multipoint
P2MP: Point to Multipoint
P2P: Point to Point
Single-Active Redundancy Mode: When only a single PE, among all the
PEs attached to an Ethernet segment, is allowed to forward traffic
to/from that Ethernet Segment, then the Ethernet segment is defined
to be operating in Single-Active redundancy mode.
All-Active Redundancy Mode: When all PEs attached to an Ethernet
segment are allowed to forward traffic to/from that Ethernet Segment,
then the Ethernet segment is defined to be operating in All-Active
redundancy mode.
4. BGP MPLS Based EVPN Overview
This section provides an overview of EVPN. An EVPN instance comprises
CEs that are connected to PEs that form the edge of the MPLS
infrastructure. A CE may be a host, a router or a switch. The PEs
provide virtual Layer 2 bridged connectivity between the CEs. There
may be multiple EVPN instances in the provider's network.
The PEs may be connected by an MPLS LSP infrastructure which provides
the benefits of MPLS technology such as fast-reroute, resiliency,
etc. The PEs may also be connected by an IP infrastructure in which
case IP/GRE tunneling or other IP tunneling can be used between the
PEs. The detailed procedures in this version of this document are
specified only for MPLS LSPs as the tunneling technology. However
these procedures are designed to be extensible to IP tunneling as the
Packet Switched Network (PSN) tunneling technology.
In an EVPN, MAC learning between PEs occurs not in the data plane (as
happens with traditional bridging in VPLS [RFC4761] or [RFC4762]) but
in the control plane. Control plane learning offers greater control
over the MAC learning process, such as restricting who learns what,
and the ability to apply policies. Furthermore, the control plane
chosen for advertising MAC reachability information is multi-protocol
(MP) BGP (similar to IP VPNs (RFC 4364)). This provides flexibility
and the ability to preserve the "virtualization" or isolation of
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groups of interacting agents (hosts, servers, virtual machines) from
each other. In EVPN, PEs advertise the MAC addresses learned from the
CEs that are connected to them, along with an MPLS label, to other
PEs in the control plane using MP-BGP. Control plane learning enables
load balancing of traffic to and from CEs that are multi-homed to
multiple PEs. This is in addition to load balancing across the MPLS
core via multiple LSPs between the same pair of PEs. In other words
it allows CEs to connect to multiple active points of attachment. It
also improves convergence times in the event of certain network
failures.
However, learning between PEs and CEs is done by the method best
suited to the CE: data plane learning, IEEE 802.1x, LLDP, 802.1aq,
ARP, management plane or other protocols.
It is a local decision as to whether the Layer 2 forwarding table on
a PE is populated with all the MAC destination addresses known to the
control plane, or whether the PE implements a cache based scheme. For
instance the MAC forwarding table may be populated only with the MAC
destinations of the active flows transiting a specific PE.
The policy attributes of EVPN are very similar to those of IP-VPN. A
EVPN instance requires a Route Distinguisher (RD) which is unique per
PE and one or more globally unique Route-Targets (RTs). A CE attaches
to a MAC-VRF on a PE, on an Ethernet interface which may be
configured for one or more Ethernet Tags, e.g., VLAN IDs. Some
deployment scenarios guarantee uniqueness of VLAN IDs across EVPN
instances: all points of attachment for a given EVPN instance use the
same VLAN ID, and no other EVPN instance uses this VLAN ID. This
document refers to this case as a "Unique VLAN EVPN" and describes
simplified procedures to optimize for it.
5. Ethernet Segment
If a CE is multi-homed to two or more PEs, the set of Ethernet links
constitutes an "Ethernet Segment". An Ethernet segment may appear to
the CE as a Link Aggregation Group (LAG). Ethernet segments have an
identifier, called the "Ethernet Segment Identifier" (ESI) which is
encoded as a ten octets integer in line format with the most
significant octet sent first. The following two ESI values are
reserved:
- ESI 0 denotes a single-homed CE.
- ESI {0xFF} (repeated 10 times) is known as MAX-ESI and is
reserved.
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In general, an Ethernet segment SHOULD have a non-reserved ESI that
is unique network wide (i.e., across all EVPN instances on all the
PEs). If the CE(s) constituting an Ethernet Segment is (are) managed
by the network operator, then ESI uniqueness should be guaranteed;
however, if the CE(s) is (are) not managed, then the operator MUST
configure a network-wide unique ESI for that Ethernet Segment. This
is required to enable auto-discovery of Ethernet Segments and DF
election.
In a network with managed and not-managed CEs, the ESI has the
following format:
+---+---+---+---+---+---+---+---+---+---+
| T | ESI Value |
+---+---+---+---+---+---+---+---+---+---+
Where:
T (ESI Type) is a 1-octet field (most significant octet) that
specifies the format of the remaining nine octets (ESI Value). The
following 6 ESI types can be used:
- Type 0 (T=0x00) - This type indicates an arbitrary nine-octet ESI
value, which is managed and configured by the operator.
- Type 1 (T=0x01) - When IEEE 802.1AX LACP is used between the PEs
and CEs, this ESI type indicates an auto-generated ESI value
determined from LACP by concatenating the following parameters:
+ CE LACP six octets System MAC address. The CE LACP System MAC
address MUST be encoded in the high order six octets of the ESI
Value field.
+ CE LACP two octets Port Key. The CE LACP port key MUST be
encoded in the two octets next to the System MAC address.
+ The remaining octet will be set to 0x00.
As far as the CE is concerned, it would treat the multiple PEs
that it is connected to as the same switch. This allows the CE
to aggregate links that are attached to different PEs in the
same bundle.
This mechanism could be used only if it produces ESIs that
satisfy the uniqueness requirement specified above.
- Type 2 (T=0x02) - This type is used in the case of indirectly
connected hosts via a bridged LAN between the CEs and the PEs. The
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ESI Value is auto-generated and determined based on the Layer 2
bridge protocol as follows: If MST is used in the bridged LAN then
the value of the ESI is derived by listening to BPDUs on the Ethernet
segment. To achieve this the PE is not required to run MST. However
the PE must learn the Root Bridge MAC address and Bridge Priority of
the root of the Internal Spanning Tree (IST) by listening to the
BPDUs. The ESI Value is constructed as follows:
+ Root Bridge six octets MAC address. The Root Bridge MAC
address MUST be encoded in the high order six octets of the
ESI Value field.
+ Root Bridge two octets Priority. The CE Root Bridge Priority
MUST be encoded in the two octets next to the Root Bridge
MAC address.
+ The remaining octet will be set to 0x00.
This mechanism could be used only if it produces ESIs that
satisfy the uniqueness requirement specified above.
- Type 3 (T=0x03) - This type indicates a MAC-based ESI Value that
can be auto-generated or configured by the operator. The ESI Value is
constructed as follows:
+ System MAC address (six octets). The PE MAC address MUST
be encoded in the high order six octets of the ESI Value field.
+ Local Discriminator value (three octets). The Local
Discriminator MUST be encoded in the low order three octets
of the ESI Value.
This mechanism could be used only if it produces ESIs that
satisfy the uniqueness requirement specified above.
- Type 4 (T=0x04) - This type indicates a router-ID ESI Value that
can be auto-generated or configured by the operator. The ESI Value is
constructed as follows:
+ Router ID (four octets). The system router ID MUST be encoded
in the high order four octets of the ESI Value field.
+ Local Discriminator value (four octets). The Local
Discriminator MUST be encoded in the four octets next to the
IP address.
+ The low order octet of the ESI Value will be set to 0x00.
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This mechanism could be used only if it produces ESIs that
satisfy the uniqueness requirement specified above.
- Type 5 (T=0x05) - This type indicates an AS-based ESI Value that
can be auto-generated or configured by the operator. The ESI Value is
constructed as follows:
+ AS number (four octets). This is an AS number owned by the
system and MUST be encoded in the high order four octets of the
ESI Value field. If a two-octet AS number is used, the high
order extra two octets will be 0x0000.
+ Local Discriminator value (four octets). The Local
Discriminator MUST be encoded in the four octets next to
the AS number.
+ The low order octet of the ESI Value will be set to 0x00.
This mechanism could be used only if it produces ESIs that
satisfy the uniqueness requirement specified above.
6. Ethernet Tag ID
An Ethernet Tag ID is a 32-bit field containing either a 12-bit or a
24-bit identifier that identifies a particular broadcast domain
(e.g., a VLAN) in an EVPN Instance. The 12-bit identifier is called
VLAN ID (VID). An EVPN Instance consists of one or more broadcast
domains (one or more VLANs). VLANs are assigned to a given EVPN
Instance by the provider of the EVPN service. A given VLAN can itself
be represented by multiple VLAN IDs (VIDs). In such cases, the PEs
participating in that VLAN for a given EVPN instance are responsible
for performing VLAN ID translation to/from locally attached CE
devices.
If a VLAN is represented by a single VID across all PE devices
participating in that VLAN for that EVPN instance, then there is no
need for VID translation at the PEs. Furthermore, some deployment
scenarios guarantee uniqueness of VIDs across all EVPN instances;
all points of attachment for a given EVPN instance use the same VID
and no other EVPN instances use that VID. This allows the RT(s) for
each EVPN instance to be derived automatically from the corresponding
VID, as described in section 7.10.1.
The following subsections discuss the relationship between broadcast
domains (e.g., VLANs), Ethernet Tag IDs (e.g., VIDs), and MAC-VRFs as
well as the setting of the Ethernet Tag ID, in the various EVPN BGP
routes (defined in section 8), for the different types of service
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interfaces described in [RFC7209].
The following value of Ethernet Tag ID is reserved:
- Ethernet Tag ID {0xFFFFFFFF} is known as MAX-ET
6.1 VLAN Based Service Interface
With this service interface, an EVPN instance consists of only a
single broadcast domain (e.g., a single VLAN). Therefore, there is a
one to one mapping between a VID on this interface and a MAC-VRF.
Since a MAC-VRF corresponds to a single VLAN, it consists of a single
bridge domain corresponding to that VLAN. If the VLAN is represented
by multiple VIDs (e.g., a different VID per Ethernet Segment per PE),
then each PE needs to perform VID translation for frames destined to
its Ethernet Segment(s). In such scenarios, the Ethernet frames
transported over MPLS/IP network SHOULD remain tagged with the
originating VID and a VID translation MUST be supported in the data
path and MUST be performed on the disposition PE. The Ethernet Tag ID
in all EVPN routes MUST be set to 0.
6.2 VLAN Bundle Service Interface
With this service interface, an EVPN instance corresponds to several
broadcast domains (e.g., several VLANs); however, only a single
bridge domain is maintained per MAC-VRF which means multiple VLANs
share the same bridge domain. This implies MAC addresses MUST be
unique across different VLANs for this service to work. In other
words, there is a many-to-one mapping between VLANs and a MAC-VRF,
and the MAC-VRF consists of a single bridge domain. Furthermore, a
single VLAN must be represented by a single VID - e.g., no VID
translation is allowed for this service interface type. The MPLS
encapsulated frames MUST remain tagged with the originating VID. Tag
translation is NOT permitted. The Ethernet Tag ID in all EVPN routes
MUST be set to 0.
6.2.1 Port Based Service Interface
This service interface is a special case of the VLAN Bundle service
interface, where all of the VLANs on the port are part of the same
service and map to the same bundle. The procedures are identical to
those described in section 6.2.
6.3 VLAN Aware Bundle Service Interface
With this service interface, an EVPN instance consists of several
broadcast domains (e.g., several VLANs) with each VLAN having its own
bridge domain - i.e., multiple bridge domains (one per VLAN) is
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maintained by a single MAC-VRF corresponding to the EVPN instance. In
the case where a single VLAN is represented by different VIDs on
different CEs and thus VID translation is required, a normalized
Ethernet Tag ID (VID) MUST be carried in the MPLS encapsulated frames
and a Ethernet Tag ID translation function MUST be supported in the
data path. This translation MUST be performed in data path on both
the imposition as well as the disposition PEs (translating to
normalized Ethernet Tag ID on imposition PE and translating to local
Ethernet Tag ID on disposition PE). The Ethernet Tag ID in all EVPN
routes MUST be set to the normalized value assigned by the EVPN
provider.
6.3.1 Port Based VLAN Aware Service Interface
This service interface is a special case of the VLAN Aware Bundle
service interface, where all of the VLANs on the port are part of the
same service and are mapped to a single bundle but without any VID
translation. The procedures are subset of those described in section
6.3.
7. BGP EVPN Routes
This document defines a new BGP Network Layer Reachability
Information (NLRI), called the EVPN NLRI.
Following is the format of the EVPN NLRI:
+-----------------------------------+
| Route Type (1 octet) |
+-----------------------------------+
| Length (1 octet) |
+-----------------------------------+
| Route Type specific (variable) |
+-----------------------------------+
The Route Type field defines encoding of the rest of the EVPN NLRI
(Route Type specific EVPN NLRI).
The Length field indicates the length in octets of the Route Type
specific field of EVPN NLRI.
This document defines the following Route Types:
+ 1 - Ethernet Auto-Discovery (A-D) route
+ 2 - MAC/IP advertisement route
+ 3 - Inclusive Multicast Ethernet Tag Route
+ 4 - Ethernet Segment Route
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The detailed encoding and procedures for these route types are
described in subsequent sections.
The EVPN NLRI is carried in BGP [RFC4271] using BGP Multiprotocol
Extensions [RFC4760] with an Address Family Identifier (AFI) of 25
(L2VPN) and a Subsequent Address Family Identifier (SAFI) of 70
(EVPN). The NLRI field in the MP_REACH_NLRI/MP_UNREACH_NLRI attribute
contains the EVPN NLRI (encoded as specified above).
In order for two BGP speakers to exchange labeled EVPN NLRI, they
must use BGP Capabilities Advertisement to ensure that they both are
capable of properly processing such NLRI. This is done as specified
in [RFC4760], by using capability code 1 (multiprotocol BGP) with an
AFI of 25 (L2VPN) and a SAFI of 70 (EVPN).
7.1. Ethernet Auto-Discovery Route
A Ethernet A-D route type specific EVPN NLRI consists of the
following:
+---------------------------------------+
| Route Distinguisher (RD) (8 octets) |
+---------------------------------------+
|Ethernet Segment Identifier (10 octets)|
+---------------------------------------+
| Ethernet Tag ID (4 octets) |
+---------------------------------------+
| MPLS Label (3 octets) |
+---------------------------------------+
For the purpose of BGP route key processing, only the Ethernet
Segment Identifier and the Ethernet Tag ID are considered to be part
of the prefix in the NLRI. The MPLS Label field is to be treated as a
route attribute as opposed to being part of the route.
For procedures and usage of this route please see section 8.2 "Fast
Convergence" and section 8.4 "Aliasing".
7.2. MAC/IP Advertisement Route
A MAC/IP advertisement route type specific EVPN NLRI consists of the
following:
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+---------------------------------------+
| RD (8 octets) |
+---------------------------------------+
|Ethernet Segment Identifier (10 octets)|
+---------------------------------------+
| Ethernet Tag ID (4 octets) |
+---------------------------------------+
| MAC Address Length (1 octet) |
+---------------------------------------+
| MAC Address (6 octets) |
+---------------------------------------+
| IP Address Length (1 octet) |
+---------------------------------------+
| IP Address (0 or 4 or 16 octets) |
+---------------------------------------+
| MPLS Label1 (3 octets) |
+---------------------------------------+
| MPLS Label2 (0 or 3 octets) |
+---------------------------------------+
For the purpose of BGP route key processing, only the Ethernet Tag
ID, MAC Address Length, MAC Address, IP Address Length, and IP
Address Address fields are considered to be part of the prefix in the
NLRI. The Ethernet Segment Identifier and MPLS Label1 and MPLS Label2
fields are to be treated as route attributes as opposed to being part
of the "route". The IP address length is in bits.
For procedures and usage of this route please see section 9
"Determining Reachability to Unicast MAC Addresses" and section 14
"Load Balancing of Unicast Packets".
7.3. Inclusive Multicast Ethernet Tag Route
An Inclusive Multicast Ethernet Tag route type specific EVPN NLRI
consists of the following:
+---------------------------------------+
| RD (8 octets) |
+---------------------------------------+
| Ethernet Tag ID (4 octets) |
+---------------------------------------+
| IP Address Length (1 octet) |
+---------------------------------------+
| Originating Router's IP Addr |
| (4 or 16 octets) |
+---------------------------------------+
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For procedures and usage of this route please see section 11
"Handling of Multi-Destination Traffic", section 13 "Processing of
Unknown Unicast Traffic" and section 16 "Multicast". The IP address
length is in bits. For the purpose of BGP route key processing, only
the Ethernet Tag ID, IP Address Length, and Originating Router's IP
Address fields are considered to be part of the prefix in the NLRI.
7.4 Ethernet Segment Route
An Ethernet Segment route type specific EVPN NLRI consists of the
following:
+---------------------------------------+
| RD (8 octets) |
+---------------------------------------+
|Ethernet Segment Identifier (10 octets)|
+---------------------------------------+
| IP Address Length (1 octet) |
+---------------------------------------+
| Originating Router's IP Addr |
| (4 or 16 octets) |
+---------------------------------------+
For procedures and usage of this route please see section 8.5
"Designated Forwarder Election". The IP address length is in bits.
For the purpose of BGP route key processing, only the Ethernet
Segment ID, IP Address Length, and Originating Router's IP Address
fields are considered to be part of the prefix in the NLRI.
7.5 ESI Label Extended Community
This extended community is a new transitive extended community with
the Type field is 0x06, and the Sub-Type of 0x01. It may be
advertised along with Ethernet Auto-Discovery routes and it enables
split-horizon procedures for multi-homed sites as described in
section 8.3 "Split Horizon". ESI Label represents an ES by the
advertising PE and it is used in split-horizon filtering by other PEs
that are connected to the same multi-homed Ethernet Segment.
Each ESI Label Extended Community is encoded as a 8-octet value as
follows:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0x06 | Sub-Type=0x01 | Flags(1 Octet)| Reserved=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved = 0 | ESI Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The low order bit of the flags octet is defined as the "Single-
Active" bit. A value of 0 means that the multi-homed site is
operating in All-Active redundancy mode and a value of 1 means that
the multi-homed site is operating in Single-Active redundancy mode.
7.6 ES-Import Route Target
This is a new transitive Route Target extended community carried with
the Ethernet Segment route. When used, it enables all the PEs
connected to the same multi-homed site to import the Ethernet Segment
routes. The value is derived automatically from the ESI by encoding
the high order 6-octet portion of the 9-octet ESI Value in the ES-
Import Route Target. The high order 6-octet of the ESI incorporates
MAC address of ESI (for type 1, 2, and 3) which when encoded in this
RT and used in the RT constrain feature, it enables proper route-
target filtering. The format of this extended community is as
follows:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0x06 | Sub-Type=0x02 | ES-Import |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ES-Import Cont'd |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This document expands the definition of the Route Target extended
community to allow the value of high order octet (Type field) to be
0x06 (in addition to the values specified in rfc4360). The value of
low order octet (Sub-Type field) of 0x02 indicates that this extended
community is of type "Route Target". The new value for Type field of
0x06 indicates that the structure of this RT is a six-octet value
(e.g., a MAC address). A BGP speaker that implements RT-Constrain
[RFC4684] MUST apply the RT Constraint procedures to the ES-import RT
as well.
For procedures and usage of this attribute, please see section 8.1
"Multi-homed Ethernet Segment Auto-Discovery".
7.7 MAC Mobility Extended Community
This extended community is a new transitive extended community with
the Type field of 0x06 and the Sub-Type of 0x00. It may be advertised
along with MAC Advertisement routes. The procedures for using this
Extended Community are described in section 15 "MAC Mobility".
The MAC Mobility Extended Community is encoded as an 8-octet value as
follows:
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0x06 | Sub-Type=0x00 |Flags(1 octet)| Reserved=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The low order bit of the flags octet is defined as the
"Sticky/static" flag and may be set to 1. A value of 1 means that the
MAC address is static and cannot move. The sequence number is used to
ensure that PEs retain the correct MAC advertisement route when
multiple updates occur for the same MAC address.
7.8 Default Gateway Extended Community
The Default Gateway community is an Extended Community of an Opaque
Type (see 3.3 of rfc4360). It is a transitive community, which means
that the first octet is 0x03. The value of the second octet (Sub-
Type) is 0x0d (Default Gateway) as assigned by IANA. The Value field
of this community is reserved (set to 0 by the senders, ignored by
the receivers).
7.9 Route Distinguisher Assignment per EVI
Route Distinguisher (RD) MUST be set to the RD of the EVI that is
advertising the NLRI. An RD MUST be assigned for a given EVI on a PE.
This RD MUST be unique across all EVIs on a PE. It is RECOMMENDED to
use the Type 1 RD [RFC4364]. The value field comprises an IP address
of the PE (typically, the loopback address) followed by a number
unique to the PE. This number may be generated by the PE. Or in the
Unique VLAN EVPN case, the low order 12 bits may be the 12 bit VLAN
ID, with the remaining high order 4 bits set to 0.
7.10 Route Targets
The EVPN route MAY carry one or more Route Target (RT) attributes.
RTs may be configured (as in IP VPNs), or may be derived
automatically.
If a PE uses RT-Constrain, the PE advertises all such RTs using RT
Constraints per [RFC4684]. The use of RT Constrains allows each
Ethernet A-D route to reach only those PEs that are configured to
import at least one RT from the set of RTs carried in the EVPN route.
7.10.1 Auto-Derivation from the Ethernet Tag ID
For the "Unique VLAN EVPN" scenario, it is highly desirable to auto-
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derive the RT from the Ethernet Tag ID (VLAN ID) for that EVPN
instance. The following is the procedure for performing such auto-
derivation.
+ The Global Administrator field of the RT MUST be set
to the Autonomous System (AS) number that the PE is
associated with.
+ The 12-bit VLAN ID MUST be encoded in the lowest 12 bits of
the Local Administrator field.
8. Multi-homing Functions
This section discusses the functions, procedures and associated BGP
routes used to support multi-homing in EVPN. This covers both multi-
homed device (MHD) as well as multi-homed network (MHN) scenarios.
8.1 Multi-homed Ethernet Segment Auto-Discovery
PEs connected to the same Ethernet segment can automatically discover
each other with minimal to no configuration through the exchange of
the Ethernet Segment route.
8.1.1 Constructing the Ethernet Segment Route
The Route-Distinguisher (RD) MUST be a Type 1 RD [RFC4364]. The value
field comprises an IP address of the PE (typically, the loopback
address) followed by 0's.
The Ethernet Segment Identifier (ESI) MUST be set to the ten octet
value described in section 5.
The BGP advertisement that advertises the Ethernet Segment route MUST
also carry an ES-Import route target, as defined in section 7.6.
The Ethernet Segment Route filtering MUST be done such that the
Ethernet Segment Route is imported only by the PEs that are multi-
homed to the same Ethernet Segment. To that end, each PE that is
connected to a particular Ethernet segment constructs an import
filtering rule to import a route that carries the ES-Import extended
community, constructed from the ESI.
8.2 Fast Convergence
In EVPN, MAC address reachability is learnt via the BGP control-plane
over the MPLS network. As such, in the absence of any fast protection
mechanism, the network convergence time is a function of the number
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of MAC Advertisement routes that must be withdrawn by the PE
encountering a failure. For highly scaled environments, this scheme
yields slow convergence.
To alleviate this, EVPN defines a mechanism to efficiently and
quickly signal, to remote PE nodes, the need to update their
forwarding tables upon the occurrence of a failure in connectivity to
an Ethernet segment. This is done by having each PE advertise a set
of one or more Ethernet A-D per Ethernet segment (per ES) routes for
each locally attached Ethernet segment (refer to section 8.2.1 below
for details on how these routes are constructed). The reason that a
PE may need to advertise more than one Ethernet A-D per ES route for
a given ES is that the ES may be in a multiplicity of EVIs and the
RTs for all of these EVIs may not fit into a single route.
Advertising a set of Ethernet A-D per ES routes for the ES allows
each route to contain a subset of the complete set of RTs.
Upon a failure in connectivity to the attached segment, the PE
withdraws the corresponding set of Ethernet A-D Per ES routes. This
triggers all PEs that receive the withdrawal to update their next-hop
adjacencies for all MAC addresses associated with the Ethernet
segment in question. If no other PE had advertised an Ethernet A-D
route for the same segment, then the PE that received the withdrawal
simply invalidates the MAC entries for that segment. Otherwise, the
PE updates the next-hop adjacencies to point to the backup PE(s).
8.2.1 Constructing Ethernet A-D per Ethernet Segment Route
This section describes the procedures used to construct the Ethernet
A-D per ES route, which is used for fast convergence (as discussed
above) and for advertising the ESI label used for split-horizon
filtering (as discussed in section 8.3). Support of this route is
REQUIRED.
The Route-Distinguisher (RD) MUST be a Type 1 RD [RFC4364]. The value
field comprises an IP address of the PE (typically, the loopback
address) followed by a number unique to the PE.
The Ethernet Segment Identifier MUST be a ten octet entity as
described in section "Ethernet Segment". The Ethernet A-D route is
not needed when the Segment Identifier is set to 0 (e.g., single-
homed scenarios).
The Ethernet Tag ID MUST be set to MAX-ET.
The MPLS label in the NLRI MUST be set to 0.
The "ESI Label Extended Community" MUST be included in the route. If
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All-Active redundancy mode is desired, then the "Single-Active" bit
in the flags of the ESI Label Extended Community MUST be set to 0 and
the MPLS label in that extended community MUST be set to a valid MPLS
label value. The MPLS label in this Extended Community is referred to
as the ESI label and MUST have the same value in each Ethernet A-D
per ES route advertised for the ES. This label MUST be a downstream
assigned MPLS label if the advertising PE is using ingress
replication for receiving multicast, broadcast or unknown unicast
traffic from other PEs. If the advertising PE is using P2MP MPLS LSPs
for sending multicast, broadcast or unknown unicast traffic, then
this label MUST be an upstream assigned MPLS label. The usage of this
label is described in section 8.3.
If Single-Active redundancy mode is desired, then the "Single-Active"
bit in the flags of the ESI Label Extended Community MUST be set to 1
and the ESI label SHOULD be set to a valid MPLS label value.
8.2.1.1. Ethernet A-D Route Targets
Each Ethernet A-D per ES route MUST carry one or more Route Target
(RT) attributes. The set of Ethernet A-D routes per ES MUST carry the
entire set of RTs for all the EVPN instances to which the Ethernet
Segment belongs.
8.3 Split Horizon
Consider a CE that is multi-homed to two or more PEs on an Ethernet
segment ES1 operating in All-Active redundancy mode. If the CE sends
a broadcast, unknown unicast, or multicast (BUM) packet to one of the
non-Designated Forwarder (non-DF) PEs, say PE1, then PE1 will forward
that packet to all or subset of the other PEs in that EVPN instance
including the Designated Forwarder (DF) PE for that Ethernet segment.
In this case the DF PE that the CE is multi-homed to MUST drop the
packet and not forward back to the CE. This filtering is referred to
as "split horizon" filtering in this document.
When a set of PEs operating in Single-Active redundancy mode, the use
of this split-horizon filtering mechanism is highly recommended
because it prevents transient loop at the time of failure or recovery
impacting the Ethernet Segment - e.g., when two PEs thinks that both
are DFs for that segment before DF election procedure settles down.
In order to achieve this split horizon function, every BUM packet
originating from a non-DF PE is encapsulated with an MPLS label that
identifies the Ethernet segment of origin (i.e. the segment from
which the frame entered the EVPN network). This label is referred to
as the ESI label, and MUST be distributed by all PEs when operating
in All-Active redundancy mode using a set of Ethernet A-D per ES
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routes per section 8.2.1 above. The ESI label SHOULD be distributed
by all PEs when operating in Single-Active redundancy mode using a
set of Ethernet A-D per ES route. This route is imported by the PEs
connected to the Ethernet Segment and also by the PEs that have at
least one EVPN instance in common with the Ethernet Segment in the
route. As described in section 8.1.1, the route MUST carry an ESI
Label Extended Community with a valid ESI label. The disposition PE
rely on the value of the ESI label to determine whether or not a BUM
frame is allowed to egress a specific Ethernet segment.
8.3.1 ESI Label Assignment
The following subsections describe the assignment procedures for the
ESI label, which differ depending on the type of tunnels being used
to deliver multi-destination packets in the EVPN network.
8.3.1.1 Ingress Replication
Each PE attached to a given ES that is operating in All-Active or
Single-Active redundancy mode and that uses ingress replication to
receive BUM traffic advertises a downstream assigned ESI label in the
set of Ethernet A-D per ES routes for that ES. This label MUST be
programmed in the platform label space by the advertising PE and the
forwarding entry for this label must result in NOT forwarding packets
received with this label onto the Ethernet segment for which the
label was distributed.
The rules for the inclusion of the ESI label in a BUM packet by the
ingress PE operating in All-Active redundancy mode are as follows:
A non-DF ingress PE MUST include the ESI label distributed by the DF
egress PE in the copy of a BUM packet sent to it.
An ingress PE (DF or non-DF) SHOULD include the ESI label distributed
by each non-DF egress PE in the copy of a BUM packet sent to it.
The rules for the inclusion of the ESI label in a BUM packet by the
ingress PE operating in Single-Active redundancy mode are as follows:
An ingress DF PE SHOULD include the ESI label distributed by the
egress PE in the copy of a BUM packet sent to it.
In both All-Active and Single-Active redundancy mode, an ingress PE
MUST NOT include an ESI label in the copy of a BUM packet sent to an
egress PE that is not attached to the ES through which the BUM packet
entered the EVI.
As an example, consider PE1 and PE2 that are multi-homed to CE1 on
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ES1 and operating in All-Active multi-homing mode. Further consider
that PE1 is using P2P or MP2P LSPs to send packets to PE2. Consider
that PE1 is the non-DF for VLAN1 and PE2 is the DF for VLAN1, and PE1
receives a BUM packet from CE1 on VLAN1 on ES1. In this scenario, PE2
distributes an Inclusive Multicast Ethernet Tag route for VLAN1
corresponding to an EVPN instance. So, when PE1 sends a BUM packet,
that it receives from CE1, it MUST first push onto the MPLS label
stack the ESI label that PE2 has distributed for ES1. It MUST then
push on the MPLS label distributed by PE2 in the Inclusive Multicast
Ethernet Tag route for VLAN1. The resulting packet is further
encapsulated in the P2P or MP2P LSP label stack required to transmit
the packet to PE2. When PE2 receives this packet, it determines the
set of ESIs to replicate the packet to from the top MPLS label, after
any P2P or MP2P LSP labels have been removed. If the next label is
the ESI label assigned by PE2 for ES1, then PE2 MUST NOT forward the
packet onto ES1. If the next label is an ESI label which has not been
assigned by PE2, then PE2 MUST drop the packet. It should be noted
that in this scenario, if PE2 receives a BUM packet for VLAN1 from
CE1, then it SHOULD encapsulate the packet with an ESI label received
from PE1 when sending it to PE1 in order to avoid any transient loop
during a failure scenario impacting ES1 (e.g., port or link failure).
8.3.1.2. P2MP MPLS LSPs
The non-DF PEs attached to a given ES that is operating in All-Active
redundancy mode and that use P2MP LSPs to send BUM traffic advertise
an upstream assigned ESI label in the set of Ethernet A-D per ES
routes for that ES. This label is upstream assigned by the PE that
advertises the route. This label MUST be programmed by the other PEs,
that are connected to the ESI advertised in the route, in the context
label space for the advertising PE. Further the forwarding entry for
this label must result in NOT forwarding packets received with this
label onto the Ethernet segment that the label was distributed for.
This label MUST also be programmed by the other PEs, that import the
route but are not connected to the ESI advertised in the route, in
the context label space for the advertising PE. Further the
forwarding entry for this label must be a POP with no other
associated action.
The DF PE attached to a given ES that is operating in Single-Active
redundancy mode and that use P2MP LSPs to send BUM traffic should
advertise an upstream assigned ESI label in the set of Ethernet A-D
per ES routes for that ES just as above paragraph.
As an example, consider PE1 and PE2 that are multi-homed to CE1 on
ES1 and operating in All-Active multi-homing mode. Also consider PE3
belongs to one of the EVPN instances of ES1. Further, assume that
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PE1 which is the non-DF, using P2MP MPLS LSPs to send BUM packets.
When PE1 sends a BUM packet, that it receives from CE1, it MUST first
push onto the MPLS label stack the ESI label that it has assigned for
the ESI that the packet was received on. The resulting packet is
further encapsulated in the P2MP MPLS label stack necessary to
transmit the packet to the other PEs. Penultimate hop popping MUST be
disabled on the P2MP LSPs used in the MPLS transport infrastructure
for EVPN. When PE2 receives this packet, it de-capsulates the top
MPLS label and forwards the packet using the context label space
determined by the top label. If the next label is the ESI label
assigned by PE1 to ES1, then PE2 MUST NOT forward the packet onto
ES1. When PE3 receives this packet, it de-capsulates the top MPLS
label and forwards the packet using the context label space
determined by the top label. If the next label is the ESI label
assigned by PE1 to ES1 and PE3 is not connected to ES1, then PE3 MUST
pop the label and flood the packet over all local ESIs in that EVPN
instance. It should be noted that when PE2 sends a BUM frame over a
P2MP LSP, it should encapsulate the frame with an ESI label even
though it is the DF for that VLAN in order to avoid any transient
loop during a failure scenario impacting ES1 (e.g., port or link
failure).
8.4 Aliasing and Backup-Path
In the case where a CE is multi-homed to multiple PE nodes, using a
LAG with All-Active redundancy, it is possible that only a single PE
learns a set of the MAC addresses associated with traffic transmitted
by the CE. This leads to a situation where remote PE nodes receive
MAC advertisement routes, for these addresses, from a single PE even
though multiple PEs are connected to the multi-homed segment. As a
result, the remote PEs are not able to effectively load-balance
traffic among the PE nodes connected to the multi-homed Ethernet
segment. This could be the case, for e.g. when the PEs perform data-
plane learning on the access, and the load-balancing function on the
CE hashes traffic from a given source MAC address to a single PE.
Another scenario where this occurs is when the PEs rely on control
plane learning on the access (e.g. using ARP), since ARP traffic will
be hashed to a single link in the LAG.
To address this issue, EVPN introduces the concept of 'Aliasing'
which is the ability of a PE to signal that it has reachability to an
EVPN instance on a given ES even when it has learnt no MAC addresses
from that EVI/ES. The Ethernet A-D per EVI route is used for this
purpose. A remote PE that receives a MAC advertisement route with
non-reserved ESI SHOULD consider the advertised MAC address to be
reachable via all PEs that have advertised reachability to that MAC
address' EVI/ES via the combination of an Ethernet A-D per EVI route
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for that EVI/ES (and Ethernet Tag if applicable) AND Ethernet A-D per
ES routes for that ES with the 'Single-Active' bit in the flags of
the ESI Label Extended Community set to 0.
Note that the Ethernet A-D per EVI route may be received by a remote
PE before it receives the set of Ethernet A-D per ES routes.
Therefore, in order to handle corner cases and race conditions, the
Ethernet A-D per EVI route MUST NOT be used for traffic forwarding by
a remote PE until it also receives the associated set of Ethernet A-D
per ES routes.
Backup-path is a closely related function, but it is used in Single-
Active redundancy mode. In this case a PE also advertises that it
has reachability to a give EVI/ES using same combination of Ethernet
A-D per EVI route and Ethernet A-D per ES route as above, but with
the 'Single-Active' bit in the flags of the ESI Label Extended
Community set to 1. A remote PE that receives a MAC advertisement
route with non-reserved ESI SHOULD consider the advertised MAC
address to be reachable via any PE that has advertised this
combination of Ethernet A-D routes and it SHOULD install a backup-
path for that MAC address.
8.4.1 Constructing Ethernet A-D per EVPN Instance Route
This section describes the procedures used to construct the Ethernet
A-D per EVPN Instance (EVI) route, which is used for aliasing (as
discussed above). Support of this route is OPTIONAL.
Route-Distinguisher (RD) MUST be set to the RD of the EVI that is
advertising the NLRI per section 7.9.
The Ethernet Segment Identifier MUST be a ten octet entity as
described in section "Ethernet Segment Identifier". The Ethernet A-D
route is not needed when the Segment Identifier is set to 0.
The Ethernet Tag ID is the identifier of an Ethernet Tag on the
Ethernet segment. This value may be a 12 bit VLAN ID, in which case
the low order 12 bits are set to the VLAN ID and the high order 20
bits are set to 0. Or it may be another Ethernet Tag used by the
EVPN. It MAY be set to the default Ethernet Tag on the Ethernet
segment or to the value 0.
Note that the above allows the Ethernet A-D route to be advertised
with one of the following granularities:
+ One Ethernet A-D route for a given <ESI, Ethernet Tag ID> tuple
per EVI. This is applicable when the PE uses MPLS-based
disposition.
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+ One Ethernet A-D route per <ESI, EVI> (where the Ethernet
Tag ID is set to 0). This is applicable when the PE uses
MAC-based disposition, or when the PE uses MPLS-based
disposition when no VLAN translation is required.
The usage of the MPLS label is described in the section on "Load
Balancing of Unicast Packets".
The Next Hop field of the MP_REACH_NLRI attribute of the route MUST
be set to the IPv4 or IPv6 address of the advertising PE.
The Ethernet A-D route MUST carry one or more Route Target (RT)
attributes per section 7.10.
8.5 Designated Forwarder Election
Consider a CE that is a host or a router that is multi-homed directly
to more than one PE in an EVPN instance on a given Ethernet segment.
One or more Ethernet Tags may be configured on the Ethernet segment.
In this scenario only one of the PEs, referred to as the Designated
Forwarder (DF), is responsible for certain actions:
- Sending multicast and broadcast traffic, on a given Ethernet
Tag on a particular Ethernet segment, to the CE.
- Flooding unknown unicast traffic (i.e. traffic for
which a PE does not know the destination MAC address),
on a given Ethernet Tag on a particular Ethernet segment
to the CE, if the environment requires flooding of
unknown unicast traffic.
Note that this behavior, which allows selecting a DF at the
granularity of <ESI, EVI> for multicast, broadcast and unknown
unicast traffic, is the default behavior in this specification.
Note that a CE always sends packets belonging to a specific flow
using a single link towards a PE. For instance, if the CE is a host
then, as mentioned earlier, the host treats the multiple links that
it uses to reach the PEs as a Link Aggregation Group (LAG). The CE
employs a local hashing function to map traffic flows onto links in
the LAG.
If a bridged network is multi-homed to more than one PE in an EVPN
network via switches, then the support of All-Active redundancy mode
requires the bridged network to be connected to two or more PEs using
a LAG.
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If a bridged network does not connect to the PEs using LAG, then only
one of the links between the switched bridged network and the PEs
must be the active link for a given EVPN instance. In this case, the
set of Ethernet A-D per ES routes advertised by each PE MUST have the
'Single-Active' bit in the flags of the ESI Label Extended Community
set to 1.
The default procedure for DF election at the granularity of <ESI,
EVI> is referred to as "service carving". With service carving, it is
possible to elect multiple DFs per Ethernet Segment (one per EVI) in
order to perform load-balancing of multi-destination traffic destined
to a given Segment. The load-balancing procedures carve up the EVI
space among the PE nodes evenly, in such a way that every PE is the
DF for a disjoint set of EVIs. The procedure for service carving is
as follows:
1. When a PE discovers the ESI of the attached Ethernet Segment, it
advertises an Ethernet Segment route with the associated ES-Import
extended community attribute.
2. The PE then starts a timer (default value = 3 seconds) to allow
the reception of Ethernet Segment routes from other PE nodes
connected to the same Ethernet Segment. This timer value should be
same across all PEs connected to the same Ethernet Segment.
3. When the timer expires, each PE builds an ordered list of the IP
addresses of all the PE nodes connected to the Ethernet Segment
(including itself), in increasing numeric value. Each IP address in
this list is extracted from the "Originator Router's IP address"
field of the advertised Ethernet Segment route. Every PE is then
given an ordinal indicating its position in the ordered list,
starting with 0 as the ordinal for the PE with the numerically lowest
IP address. The ordinals are used to determine which PE node will be
the DF for a given EVPN instance on the Ethernet Segment using the
following rule:
Assuming a redundancy group of N PE nodes, the PE with ordinal i is
the DF for an EVPN instance with an associated Ethernet Tag value V
when (V mod N) = i. In the case where multiple Ethernet Tags are
associated with a single EVPN instance, then the numerically lowest
Ethernet Tag value in that EVPN instance on that ES MUST be used in
the modulo function.
It should be noted that using "Originator Router's IP address" field
in the Ethernet Segment route to get the PE IP address needed for the
ordered list, allows for a CE to be multi-homed across different ASes
if such need ever arises.
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4. The PE that is elected as a DF for a given EVPN instance will
unblock traffic for the Ethernet Tags associated with that EVPN
instance. Note that the DF PE unblocks multi-destination traffic in
the egress direction towards the Segment. All non-DF PEs continue to
drop multi-destination traffic (for the associated EVPN instances) in
the egress direction towards the Segment.
In the case of link or port failure, the affected PE withdraws its
Ethernet Segment route. This will re-trigger the service carving
procedures on all the PEs in the RG. For PE node failure, or upon PE
commissioning or decommissioning, the PEs re-trigger the service
carving. In case of a Single-Active multi-homing, when a service
moves from one PE in the RG to another PE as a result of re-carving,
the PE, which ends up being the elected DF for the service, SHOULD
trigger a MAC address flush notification towards the associated
Ethernet Segment. This can be done, for e.g. using IEEE 802.1ak MVRP
'new' declaration.
8.6. Interoperability with Single-homing PEs
Let's refer to PEs that only support single-homed CE devices as
single-homing PEs. For single-homing PEs, all the above multi-homing
procedures can be omitted; however, to allow for single-homing PEs to
fully inter-operate with multi-homing PEs, some of the multi-homing
procedures described above SHOULD be supported even by single-homing
PEs:
- procedures related to processing Ethernet A-D route for the purpose
of Fast Convergence (8.2 Fast Convergence), to let single-homing PEs
benefit from fast convergence
- procedures related to processing Ethernet A-D route for the purpose
of Aliasing (8.4 Aliasing and Backup-path), to let single-homing PEs
benefit from load balancing
- procedures related to processing Ethernet A-D route for the purpose
of Backup-path (8.4 Aliasing and Backup-path), to let single-homing
PEs to benefit from the corresponding convergence improvement
9. Determining Reachability to Unicast MAC Addresses
PEs forward packets that they receive based on the destination MAC
address. This implies that PEs must be able to learn how to reach a
given destination unicast MAC address.
There are two components to MAC address learning, "local learning"
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and "remote learning":
9.1. Local Learning
A particular PE must be able to learn the MAC addresses from the CEs
that are connected to it. This is referred to as local learning.
The PEs in a particular EVPN instance MUST support local data plane
learning using standard IEEE Ethernet learning procedures. A PE must
be capable of learning MAC addresses in the data plane when it
receives packets such as the following from the CE network:
- DHCP requests
- ARP request for its own MAC.
- ARP request for a peer.
Alternatively PEs MAY learn the MAC addresses of the CEs in the
control plane or via management plane integration between the PEs and
the CEs.
There are applications where a MAC address that is reachable via a
given PE on a locally attached Segment (e.g. with ESI X) may move
such that it becomes reachable via another PE on another Segment
(e.g. with ESI Y). This is referred to as a "MAC Mobility".
Procedures to support this are described in section "MAC Mobility".
9.2. Remote learning
A particular PE must be able to determine how to send traffic to MAC
addresses that belong to or are behind CEs connected to other PEs
i.e. to remote CEs or hosts behind remote CEs. We call such MAC
addresses "remote" MAC addresses.
This document requires a PE to learn remote MAC addresses in the
control plane. In order to achieve this, each PE advertises the MAC
addresses it learns from its locally attached CEs in the control
plane, to all the other PEs in that EVPN instance, using MP-BGP and
specifically the MAC Advertisement route.
9.2.1. Constructing MAC/IP Address Advertisement
BGP is extended to advertise these MAC addresses using the MAC/IP
Advertisement route type in the EVPN NLRI.
The RD MUST be the RD of the EVI that is advertising the NLRI. The
procedures for setting the RD for a given EVI are described in
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section 7.9.
The Ethernet Segment Identifier is set to the ten octet ESI described
in section "Ethernet Segment".
The Ethernet Tag ID may be zero or may represent a valid Ethernet Tag
ID. This field may be non-zero when there are multiple bridge
domains in the MAC-VRF (i.e., the PE needs to perform qualified
learning for the VLANs in that MAC-VRF).
When the the Ethernet Tag ID in the NLRI is set to a non-zero value,
for a particular bridge domain, then this Ethernet Tag ID may either
be the CE's Ethernet tag value (e.g., CE VLAN ID) or the EVPN
provider's Ethernet tag value (e.g., provider VLAN ID). The latter
would be the case if the CE Ethernet tags (e.g., CE VLAN ID) for a
particular bridge domain are different on different CEs.
The MAC address length field is in bits and it is set to 48. The MAC
address length values other than 48 bits, are outside the scope of
this document. The encoding of a MAC address MUST be the 6-octet MAC
address specified by [802.1D-ORIG] [802.1D-REV].
The IP Address Field is optional. By default, the IP Address Length
field is set to 0 and the IP address field is omitted from the route.
When a valid IP address needs to be advertised, it is then encoded in
this route. When an IP address is present, the IP Address Length
field is in bits and it is set to 32 or 128 bits. Other IP Address
Length values are outside the scope of this document. The encoding of
an IP address MUST be either 4 octets for IPv4 or 16 octets for IPv6.
The length field of EVPN NLRI (which is in octets and is described in
section 7) is sufficient to determine whether an IP address is
encoded in this route and if so, whether the encoded IP address is
IPV4 or IPv6.
The MPLS label1 field is encoded as 3 octets, where the high-order 20
bits contain the label value. The MPLS label1 MUST be downstream
assigned and it is associated with the MAC address being advertised
by the advertising PE. The advertising PE uses this label when it
receives an MPLS-encapsulated packet to perform forwarding based on
the destination MAC address toward the CE. The forwarding procedures
are specified in sections 13 and 14.
A PE may advertise the same single EVPN label for all MAC addresses
in a given EVI. This label assignment is referred to as a per EVI
label assignment. Alternatively, a PE may advertise a unique EVPN
label per <ESI, Ethernet Tag> combination. This label assignment is
referred to as a per <ESI, Ethernet Tag> label assignment. As a third
option, a PE may advertise a unique EVPN label per MAC address. This
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label assignment is referred to as a per MAC label assignment. All of
these label assignment methods have their tradeoffs. The choice of a
particular label assignment methodology is purely local to the PE
that originates the route.
Per EVI label assignment requires the least number of EVPN labels,
but requires a MAC lookup in addition to an MPLS lookup on an egress
PE for forwarding. On the other hand, a unique label per <ESI,
Ethernet Tag> or a unique label per MAC allows an egress PE to
forward a packet that it receives from another PE, to the connected
CE, after looking up only the MPLS labels without having to perform a
MAC lookup. This includes the capability to perform appropriate VLAN
ID translation on egress to the CE.
The MPLS label2 field is an optional field and if it is present, then
it is encoded as 3 octets, where the high-order 20 bits contain the
label value.
The Next Hop field of the MP_REACH_NLRI attribute of the route MUST
be set to the IPv4 or IPv6 address of the advertising PE.
The BGP advertisement for the MAC advertisement route MUST also carry
one or more Route Target (RT) attributes. RTs may be configured (as
in IP VPNs), or may be derived automatically from the Ethernet Tag
ID, in the Unique VLAN case, as described in section 7.10.1.
It is to be noted that this document does not require PEs to create
forwarding state for remote MACs when they are learnt in the control
plane. When this forwarding state is actually created is a local
implementation matter.
9.2.2 Route Resolution
If the Ethernet Segment Identifier field in a received MAC
Advertisement route is set to the reserved ESI value of 0 or MAX-ESI,
then if the receiving PE decides to install forwarding state for the
associated MAC address, it MUST be based on the MAC Advertisement
route alone.
If the Ethernet Segment Identifier field in a received MAC
Advertisement route is set to a non-reserved ESI, and the receiving
PE is locally attached to the same ESI, then the PE does not alter
its forwarding state based on the received route. This ensures that
local routes are preferred to remote routes.
If the Ethernet Segment Identifier field in a received MAC
Advertisement route is set to a non-reserved ESI, then if the
receiving PE decides to install forwarding state for the associated
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MAC address, it MUST be when both the MAC Advertisement route AND the
associated set of Ethernet A-D per ES routes have been received. The
dependency of MAC routes installation on Ethernet A-D per ES routes,
is to ensure that MAC routes don't get accidentally installed during
mass withdraw period.
To illustrate this with an example, consider two PEs (PE1 and PE2)
connected to a multi-homed Ethernet Segment ES1. All-Active
redundancy mode is assumed. A given MAC address M1 is learnt by PE1
but not PE2. On PE3, the following states may arise:
T1- When the MAC Advertisement Route from PE1 and the set of Ethernet
A-D per ES routes and Ethernet A-D per EVI routes from PE1 and PE2
are received, PE3 can forward traffic destined to M1 to both PE1 and
PE2.
T2- If after T1, PE1 withdraws its set of Ethernet A-D per ES routes,
then PE3 forwards traffic destined to M1 to PE2 only.
T2'- If after T1, PE2 withdraws its set of Ethernet A-D per ES
routes, then PE3 forwards traffic destined to M1 to PE1 only.
T2''- If after T1, PE1 withdraws its MAC Advertisement route, then
PE3 treats traffic to M1 as unknown unicast.
T3- PE2 also advertises a MAC route for M1 and then PE1 withdraws its
MAC route for M1. PE3 continues forwarding traffic destined to M1 to
both PE1 and PE2. In other words, despite M1 withdrawal by PE1, PE3
forwards the traffic destined to M1 to both PE1 and PE2. This is
because a flow from the CE, resulting in M1 traffic getting hashed to
PE1, can get terminated resulting in M1 to aged out in PE1; however,
M1 can be reachable by both PE1 and PE2.
10. ARP and ND
The IP address field in the MAC advertisement route may optionally
carry one of the IP addresses associated with the MAC address. This
provides an option which can be used to minimize the flooding of ARP
or Neighbor Discovery (ND) messages over the MPLS network and to
remote CEs. This option also minimizes ARP (or ND) message processing
on end-stations/hosts connected to the EVPN network. A PE may learn
the IP address associated with a MAC address in the control or
management plane between the CE and the PE. Or, it may learn this
binding by snooping certain messages to or from a CE. When a PE
learns the IP address associated with a MAC address, of a locally
connected CE, it may advertise this address to other PEs by including
it in the MAC Advertisement route. The IP Address may be an IPv4
address encoded using four octets, or an IPv6 address encoded using
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sixteen octets. For ARP and ND purposes, the IP Address length field
MUST be set to 32 for an IPv4 address or to 128 for an IPv6 address.
If there are multiple IP addresses associated with a MAC address,
then multiple MAC advertisement routes MUST be generated, one for
each IP address. For instance, this may be the case when there are
both an IPv4 and an IPv6 address associated with the same MAC address
for dual-IP stack scenarios. When the IP address is dissociated with
the MAC address, then the MAC advertisement route with that
particular IP address MUST be withdrawn.
Note that a MAC-only route can be advertised along with but
independent from MAC/IP route for scenarios where the MAC learning
over access network/node is done in data-plane and independent from
ARP snooping that generates MAC/IP route. In such scenarios when the
ARP entry times out and causes the MAC/IP to be withdrawn, then the
MAC information will not be lost. In scenarios where host MAC/IP is
learned via management or control plane, then the sender PE may only
generates and advertises MAC/IP route. If the receiving PE receives
both the MAC-only route and the MAC/IP route, then when it receives a
withdraw message for the MAC/IP route, it MUST delete the
corresponding entry from the ARP table but not the MAC entry from the
MAC-VRF table unless it receives a withdraw message for MAC-only
route.
When a PE receives an ARP request for an IP address from a CE, and if
the PE has the MAC address binding for that IP address, the PE SHOULD
perform ARP proxy by responding to the ARP request.
10.1 Default Gateway
When a PE needs to perform inter-subnet forwarding where each subnet
is represented by a different broadcast domain (e.g., different VLAN)
the inter-subnet forwarding is performed at layer 3 and the PE that
performs such function is called the default gateway for the EVPN
instance. In this case when the PE receives an ARP Request for the IP
address configured as the default gateway address, the PE originates
an ARP Reply.
Each PE that acts as a default gateway for a given EVPN instance MAY
advertise in the EVPN control plane its default gateway MAC address
using the MAC/IP advertisement route, and indicates that such route
is associated with the default gateway. This is accomplished by
requiring the route to carry the Default Gateway extended community
defined in [Section 7.8 Default Gateway Extended Community]. The ESI
field is set to zero when advertising the MAC route with the Default
Gateway extended community.
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The IP address field of the MAC/IP advertisement route is set to the
default GW IP address for that subnet (e.g., EVPN instance). For a
given subnet (e.g., VLAN or EVPN instance), the default GW IP address
is the same across all the participant PEs. The inclusion of this IP
address enables the receiving PE to check its configured default GW
IP address against the one received in the MAC/IP advertisement route
for that subnet (or EVPN instance) and if there is a discrepancy,
then the PE SHOULD notify the operator and log an error message.
Unless it is known a priori (by means outside of this document) that
all PEs of a given EVPN instance act as a default gateway for that
EVPN instance, the MPLS label MUST be set to a valid downstream
assigned label.
Furthermore, even if all PEs of a given EVPN instance do act as a
default gateway for that EVPN instance, but only some, but not all,
of these PEs have sufficient (routing) information to provide inter-
subnet routing for all the inter-subnet traffic originated within the
subnet associated with the EVPN instance, then when such PE
advertises in the EVPN control plane its default gateway MAC address
using the MAC advertisement route, and indicates that such route is
associated with the default gateway, the route MUST carry a valid
downstream assigned label.
If all PEs of a given EVPN instance act as a default gateway for that
EVPN instance, and the same default gateway MAC address is used
across all gateway devices, then no such advertisement is needed.
However, if each default gateway uses a different MAC address, then
each default gateway needs to be aware of other gateways' MAC
addresses and thus the need for such advertisement. This is called
MAC address aliasing since a single default GW can be represented by
multiple MAC addresses.
Each PE that receives this route and imports it as per procedures
specified in this document follows the procedures in this section
when replying to ARP Requests that it receives.
Each PE that acts as a default gateway for a given EVPN instance that
receives this route and imports it as per procedures specified in
this document MUST create MAC forwarding state that enables it to
apply IP forwarding to the packets destined to the MAC address
carried in the route.
11. Handling of Multi-Destination Traffic
Procedures are required for a given PE to send broadcast or multicast
traffic, received from a CE encapsulated in a given Ethernet Tag
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(VLAN) in an EVPN instance, to all the other PEs that span that
Ethernet Tag (VLAN) in that EVPN instance. In certain scenarios,
described in section "Processing of Unknown Unicast Packets", a given
PE may also need to flood unknown unicast traffic to other PEs.
The PEs in a particular EVPN instance may use ingress replication,
P2MP LSPs or MP2MP LSPs to send unknown unicast, broadcast or
multicast traffic to other PEs.
Each PE MUST advertise an "Inclusive Multicast Ethernet Tag Route" to
enable the above. The following subsection provides the procedures to
construct the Inclusive Multicast Ethernet Tag route. Subsequent
subsections describe in further detail its usage.
11.1. Constructing Inclusive Multicast Ethernet Tag Route
The RD MUST be the RD of the EVI that is advertising the NLRI. The
procedures for setting the RD for a given EVPN instance on a PE are
described in section 7.9.
The Ethernet Tag ID is the identifier of the Ethernet Tag. It may be
set to 0 or to a valid Ethernet Tag value.
The Originating Router's IP address MUST be set to an IP address of
the PE that should be common for all the EVIs on the PE (e.,g., this
address may be PE's loopback address). The IP Address Length field is
in bits.
The Next Hop field of the MP_REACH_NLRI attribute of the route MUST
be set to the same IP address as the one carried in the Originating
Router's IP Address field.
The BGP advertisement for the Inclusive Multicast Ethernet Tag route
MUST also carry one or more Route Target (RT) attributes. The
assignment of RTs described in the section 7.10 MUST be followed.
11.2. P-Tunnel Identification
In order to identify the P-Tunnel used for sending broadcast, unknown
unicast or multicast traffic, the Inclusive Multicast Ethernet Tag
route MUST carry a "PMSI Tunnel Attribute" as specified in [BGP
MVPN].
Depending on the technology used for the P-tunnel for the EVPN
instance on the PE, the PMSI Tunnel attribute of the Inclusive
Multicast Ethernet Tag route is constructed as follows.
+ If the PE that originates the advertisement uses a
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P-Multicast tree for the P-tunnel for EVPN, the PMSI
Tunnel attribute MUST contain the identity of the tree
(note that the PE could create the identity of the
tree prior to the actual instantiation of the tree).
+ A PE that uses a P-Multicast tree for the P-tunnel MAY
aggregate two or more EVPN instances (EVIs) present
on the PE onto the same tree. In this case, in addition
to carrying the identity of the tree, the PMSI Tunnel
attribute MUST carry an MPLS upstream assigned label which
the PE has bound uniquely to the EVI associated with this
update (as determined by its RTs).
If the PE has already advertised Inclusive Multicast
Ethernet Tag routes for two or more EVIs that it now
desires to aggregate, then the PE MUST re-advertise
those routes. The re-advertised routes MUST be the same
as the original ones, except for the PMSI Tunnel attribute
and the label carried in that attribute.
+ If the PE that originates the advertisement uses ingress
replication for the P-tunnel for EVPN, the route MUST
include the PMSI Tunnel attribute with the Tunnel Type set to
Ingress Replication and Tunnel Identifier set to a routable
address of the PE. The PMSI Tunnel attribute MUST carry a
downstream assigned MPLS label. This label is used to
demultiplex the broadcast, multicast or unknown unicast EVPN
traffic received over a MP2P tunnel by the PE.
+ The Leaf Information Required flag of the PMSI Tunnel
attribute MUST be set to zero, and MUST be ignored on receipt.
12. Processing of Unknown Unicast Packets
The procedures in this document do not require the PEs to flood
unknown unicast traffic to other PEs. If PEs learn CE MAC addresses
via a control plane protocol, the PEs can then distribute MAC
addresses via BGP, and all unicast MAC addresses will be learnt prior
to traffic to those destinations.
However, if a destination MAC address of a received packet is not
known by the PE, the PE may have to flood the packet. When flooding,
one must take into account "split horizon forwarding" as follows: The
principles behind the following procedures are borrowed from the
split horizon forwarding rules in VPLS solutions [RFC4761] and
[RFC4762]. When a PE capable of flooding (say PEx) receives an
unknown destination MAC address, it floods the frame. If the frame
arrived from an attached CE, PEx must send a copy of that frame on
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every Ethernet Segment (belonging to that EVI) for which it is the
DF, other than the Ethernet Segment on which it received the frame.
In addition, the PE must flood the frame to all other PEs
participating in that EVPN instance. If, on the other hand, the frame
arrived from another PE (say PEy), PEx must send a copy of the packet
on each Ethernet Segment (belonging to that EVI) for which it is the
DF. PEx MUST NOT send the frame to other PEs, since PEy would have
already done so. Split horizon forwarding rules apply to unknown MAC
addresses.
Whether or not to flood packets to unknown destination MAC addresses
should be an administrative choice, depending on how learning happens
between CEs and PEs.
The PEs in a particular EVPN instance may use ingress replication
using RSVP-TE P2P LSPs or LDP MP2P LSPs for sending unknown unicast
traffic to other PEs. Or they may use RSVP-TE P2MP or LDP P2MP for
sending such traffic to other PEs.
12.1. Ingress Replication
If ingress replication is in use, the P-Tunnel attribute, carried in
the Inclusive Multicast Ethernet Tag routes for the EVPN instance,
specifies the downstream label that the other PEs can use to send
unknown unicast, multicast or broadcast traffic for that EVPN
instance to this particular PE.
The PE that receives a packet with this particular MPLS label MUST
treat the packet as a broadcast, multicast or unknown unicast packet.
Further if the MAC address is a unicast MAC address, the PE MUST
treat the packet as an unknown unicast packet.
12.2. P2MP MPLS LSPs
The procedures for using P2MP LSPs are very similar to VPLS
procedures [RFC7117]. The P-Tunnel attribute used by a PE for sending
unknown unicast, broadcast or multicast traffic for a particular EVPN
instance is advertised in the Inclusive Ethernet Tag Multicast route
as described in section "Handling of Multi-Destination Traffic".
The P-Tunnel attribute specifies the P2MP LSP identifier. This is the
equivalent of an Inclusive tree in [RFC7117]. Note that multiple
Ethernet Tags, which may be in different EVPN instances, may use the
same P2MP LSP, using upstream labels [RFC7117]. This is the
equivalent of an Aggregate Inclusive tree in [RFC7117]. When P2MP
LSPs are used for flooding unknown unicast traffic, packet re-
ordering is possible.
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The PE that receives a packet on the P2MP LSP specified in the PMSI
Tunnel Attribute MUST treat the packet as a broadcast, multicast or
unknown unicast packet. Further if the MAC address is a unicast MAC
address, the PE MUST treat the packet as an unknown unicast packet.
13. Forwarding Unicast Packets
This section describes procedures for forwarding unicast packets by
PEs, where such packets are received from either directly connected
CEs, or from some other PEs.
13.1. Forwarding packets received from a CE
When a PE receives a packet from a CE, on a given Ethernet Tag ID, it
must first look up the source MAC address of the packet. In certain
environments that enable MAC security, the source MAC address MAY be
used to validate the host identity and determine that traffic from
the host can be allowed into the network. Source MAC lookup MAY also
be used for local MAC address learning.
If the PE decides to forward the packet, the destination MAC address
of the packet must be looked up. If the PE has received MAC address
advertisements for this destination MAC address from one or more
other PEs or learned it from locally connected CEs, it is considered
as a known MAC address. Otherwise, the MAC address is considered as
an unknown MAC address.
For known MAC addresses the PE forwards this packet to one of the
remote PEs or to a locally attached CE. When forwarding to a remote
PE, the packet is encapsulated in the EVPN MPLS label advertised by
the remote PE, for that MAC address, and in the MPLS LSP label stack
to reach the remote PE.
If the MAC address is unknown and if the administrative policy on the
PE requires flooding of unknown unicast traffic then:
- The PE MUST flood the packet to other PEs. The PE MUST first
encapsulate the packet in the ESI MPLS label as described in section
8.3. If ingress replication is used, the packet MUST be replicated to
each remote PE with the VPN label being an MPLS label determined as
follows: This is the MPLS label advertised by the remote PE in a PMSI
Tunnel Attribute in the Inclusive Multicast Ethernet Tag route for an
<EVPN instance, Ethernet Tag> combination. The Ethernet Tag in the
route may be the same as the Ethernet Tag associated with the
interface on which the ingress PE receives the packet. If P2MP LSPs
are being used the packet MUST be sent on the P2MP LSP that the PE is
the root of for the Ethernet Tag in the EVPN instance. If the same
P2MP LSP is used for all Ethernet Tags, then all the PEs in the EVPN
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instance MUST be the leaves of the P2MP LSP. If a distinct P2MP LSP
is used for a given Ethernet Tag in the EVPN instance, then only the
PEs in the Ethernet Tag MUST be the leaves of the P2MP LSP. The
packet MUST be encapsulated in the P2MP LSP label stack.
If the MAC address is unknown then, if the administrative policy on
the PE does not allow flooding of unknown unicast traffic:
- The PE MUST drop the packet.
13.2. Forwarding packets received from a remote PE
This section described the procedures for forwarding known and
unknown unicast packets received from a remote PE.
13.2.1. Unknown Unicast Forwarding
When a PE receives an MPLS packet from a remote PE then, after
processing the MPLS label stack, if the top MPLS label ends up being
a P2MP LSP label associated with an EVPN instance or in case of
ingress replication the downstream label advertised in the P-Tunnel
attribute, and after performing the split horizon procedures
described in section 8.3:
- If the PE is the designated forwarder of BUM traffic on a
particular set of ESIs for the Ethernet Tag, the default behavior is
for the PE to flood the packet on these ESIs. In other words, the
default behavior is for the PE to assume that for BUM traffic, it is
not required to perform a destination MAC address lookup. As an
option, the PE may perform a destination MAC lookup to flood the
packet to only a subset of the CE interfaces in the Ethernet Tag. For
instance the PE may decide to not flood an BUM packet on certain
Ethernet segments even if it is the DF on the Ethernet segment, based
on administrative policy.
- If the PE is not the designated forwarder on any of the ESIs for
the Ethernet Tag, the default behavior is for it to drop the packet.
13.2.2. Known Unicast Forwarding
If the top MPLS label ends up being an EVPN label that was advertised
in the unicast MAC advertisements, then the PE either forwards the
packet based on CE next-hop forwarding information associated with
the label or does a destination MAC address lookup to forward the
packet to a CE.
14. Load Balancing of Unicast Frames
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This section specifies the load balancing procedures for sending
known unicast frames to a multi-homed CE.
14.1. Load balancing of traffic from a PE to remote CEs
Whenever a remote PE imports a MAC advertisement for a given <ESI,
Ethernet Tag> in an EVI, it MUST examine all imported Ethernet A-D
routes for that ESI in order to determine the load-balancing
characteristics of the Ethernet segment.
14.1.1 Single-Active Redundancy Mode
For a given ES, if the remote PE has imported the set of Ethernet A-D
per ES routes from at least one PE, where the "Single-Active" flag in
the ESI Label Extended Community is set, then the remote PE MUST
deduce that the ES is operating in Single-Active redundancy mode. As
such, the MAC address will be reachable only via the PE announcing
the associated MAC Advertisement route - this is referred to as the
primary PE. The other PEs advertising the set of Ethernet A-D per ES
routes for the same ES provide backup paths for that ES, in case the
primary PE encounters a failure, and are referred to as backup PEs.
It should be noted that the primary PE for a given <ES, EVI> is the
DF for that <ES, EVI>.
If the primary PE encounters a failure, it MAY withdraw its set of
Ethernet A-D per ES routes for the affected ES prior to withdrawing
it set of MAC Advertisement routes.
If there is only one backup PE for a given ES, the remote PE MAY use
the primary PE's withdrawal of its set of Ethernet A-D per ES routes
as a trigger to update its forwarding entries, for the associated MAC
addresses, to point towards the backup PE. As the backup PE starts
learning the MAC addresses over its attached ES, it will start
sending MAC Advertisement routes while the failed PE withdraws its
routes. This mechanism minimizes the flooding of traffic during fail-
over events.
If there is more than one backup PE for a given ES, the remote PE
MUST use the primary PE's withdrawal of its set of Ethernet A-D per
ES routes as a trigger to start flooding traffic for the associated
MAC addresses (as long as flooding of unknown unicast is
administratively allowed), as it is not possible to select a single
backup PE.
14.1.2 All-Active Redundancy Mode
For a given ES, if the remote PE has imported the set of Ethernet A-D
per ES routes from one or more PEs and none of them have the "Single-
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Active" flag in the ESI Label Extended Community set, then the remote
PE MUST deduce that the ES is operating in All-Active redundancy
mode. A remote PE that receives a MAC advertisement route with non-
reserved ESI SHOULD consider the advertised MAC address to be
reachable via all PEs that have advertised reachability to that MAC
address' EVI/ES via the combination of an Ethernet A-D per EVI route
for that EVI/ES (and Ethernet Tag if applicable) AND an Ethernet A-D
per ES route for that ES. The remote PE MUST use received MAC
Advertisement routes and Ethernet A-D per EVI/per ES routes to
construct the set of next-hops for the advertised MAC address.
Each next-hop comprises an MPLS label stack that is to be used by the
egress PE to forward the packet. This label stack is determined as
follows:
-If the next-hop is constructed as a result of a MAC route then this
label stack MUST be used. However, if the MAC route doesn't exist for
that PE, then the next-hop and MPLS label stack is constructed as a
result of the Ethernet A-D routes. Note that the following
description applies to determining the label stack for a particular
next-hop to reach a given PE, from which the remote PE has received
and imported Ethernet A-D routes that have the matching ESI and
Ethernet Tag as the one present in the MAC advertisement. The
Ethernet A-D routes mentioned in the following description refer to
the ones imported from this given PE.
-If a set of Ethernet A-D per ES routes for that ES AND an Ethernet
A-D route per EVI exist, only then the label from that latter route
must be used.
The following example explains the above.
Consider a CE (CE1) that is dual-homed to two PEs (PE1 and PE2) on a
LAG interface (ES1), and is sending packets with source MAC address
MAC1 on VLAN1 (mapped to EVI1). A remote PE, say PE3, is able to
learn that MAC1 is reachable via PE1 and PE2. Both PE1 and PE2 may
advertise MAC1 in BGP if they receive packets with MAC1 from CE1. If
this is not the case, and if MAC1 is advertised only by PE1, PE3
still considers MAC1 as reachable via both PE1 and PE2 as both PE1
and PE2 advertise a set of Ethernet A-D per ES routes for ES1 as well
as an Ethernet A-D per EVI route for <EVI1, ES1>.
The MPLS label stack to send the packets to PE1 is the MPLS LSP stack
to get to PE1 (at top of the stack) followed by the EVPN label
advertised by PE1 for CE1's MAC .
The MPLS label stack to send packets to PE2 is the MPLS LSP stack to
get to PE2 (at top of the stack) followed by the MPLS label in the
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Ethernet A-D route advertised by PE2 for <ES1, VLAN1>, if PE2 has not
advertised MAC1 in BGP.
We will refer to these label stacks as MPLS next-hops.
The remote PE (PE3) can now load balance the traffic it receives from
its CEs, destined for CE1, between PE1 and PE2. PE3 may use N-Tuple
flow information to hash traffic into one of the MPLS next-hops for
load balancing of IP traffic. Alternatively PE3 may rely on the
source MAC addresses for load balancing.
Note that once PE3 decides to send a particular packet to PE1 or PE2
it can pick one out of multiple possible paths to reach the
particular remote PE using regular MPLS procedures. For instance, if
the tunneling technology is based on RSVP-TE LSPs, and PE3 decides to
send a particular packet to PE1, then PE3 can choose from multiple
RSVP-TE LSPs that have PE1 as their destination.
When PE1 or PE2 receive the packet destined for CE1 from PE3, if the
packet is a known unicast, it is forwarded to CE1. If it is a BUM
packet then only one of PE1 or PE2 must forward the packet to the CE.
Which of PE1 or PE2 forward this packet to the CE is determined based
on which of the two is the DF.
14.2. Load balancing of traffic between a PE and a local CE
A CE may be configured with more than one interface connected to
different PEs or the same PE for load balancing, using a technology
such as LAG. The PE(s) and the CE can load balance traffic onto these
interfaces using one of the following mechanisms.
14.2.1. Data plane learning
Consider that the PEs perform data plane learning for local MAC
addresses learned from local CEs. This enables the PE(s) to learn a
particular MAC address and associate it with one or more interfaces,
if the technology between the PE and the CE supports multi-pathing.
The PEs can now load balance traffic destined to that MAC address on
the multiple interfaces.
Whether the CE can load balance traffic that it generates on the
multiple interfaces is dependent on the CE implementation.
14.2.2. Control plane learning
The CE can be a host that advertises the same MAC address using a
control protocol on all interfaces. This enables the PE(s) to learn
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the host's MAC address and associate it with all interfaces. The PEs
can now load balance traffic destined to the host on all these
interfaces. The host can also load balance the traffic it generates
onto these interfaces and the PE that receives the traffic employs
EVPN forwarding procedures to forward the traffic.
15. MAC Mobility
It is possible for a given host or end-station (as defined by its MAC
address) to move from one Ethernet segment to another; this is
referred to as 'MAC Mobility' or 'MAC move' and it is different from
the multi-homing situation in which a given MAC address is reachable
via multiple PEs for the same Ethernet segment. In a MAC move, there
would be two sets of MAC Advertisement routes, one set with the new
Ethernet segment and one set with the previous Ethernet segment, and
the MAC address would appear to be reachable via each of these
segments.
In order to allow all of the PEs in the EVPN instance to correctly
determine the current location of the MAC address, all advertisements
of it being reachable via the previous Ethernet segment MUST be
withdrawn by the PEs, for the previous Ethernet segment, that had
advertised it.
If local learning is performed using the data plane, these PEs will
not be able to detect that the MAC address has moved to another
Ethernet segment and the receipt of MAC Advertisement routes, with
the MAC Mobility extended community attribute, from other PEs serves
as the trigger for these PEs to withdraw their advertisements. If
local learning is performed using the control or management planes,
these interactions serve as the trigger for these PEs to withdraw
their advertisements.
In a situation where there are multiple moves of a given MAC,
possibly between the same two Ethernet segments, there may be
multiple withdrawals and re-advertisements. In order to ensure that
all PEs in the EVPN instance receive all of these correctly through
the intervening BGP infrastructure, it is necessary to introduce a
sequence number into the MAC Mobility extended community attribute.
An implementation MUST handle the scenarios where the sequence number
wraps around to process mobility event correctly.
Every MAC mobility event for a given MAC address will contain a
sequence number that is set using the following rules:
- A PE advertising a MAC address for the first time advertises it
with no MAC Mobility extended community attribute.
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- A PE detecting a locally attached MAC address for which it had
previously received a MAC Advertisement route with a different
Ethernet segment identifier advertises the MAC address in a MAC
Advertisement route tagged with a MAC Mobility extended community
attribute with a sequence number one greater than the sequence number
in the MAC mobility attribute of the received MAC Advertisement
route. In the case of the first mobility event for a given MAC
address, where the received MAC Advertisement route does not carry a
MAC Mobility attribute, the value of the sequence number in the
received route is assumed to be 0 for purpose of this processing.
- A PE detecting a locally attached MAC address for which it had
previously received a MAC Advertisement route with the same non-zero
Ethernet segment identifier advertises it with:
i. no MAC Mobility extended community attribute, if the received
route did not carry said attribute.
ii. a MAC Mobility extended community attribute with the sequence
number equal to the highest of the sequence number(s) in the
received MAC Advertisement route(s), if the received route(s) is
(are) tagged with a MAC Mobility extended community attribute.
- A PE detecting a locally attached MAC address for which it had
previously received a MAC Advertisement route with the same zero
Ethernet segment identifier (single-homed scenarios) advertises it
with MAC mobility extended community attribute with the sequence
number set properly. In case of single-homed scenarios, there is no
need for ESI comparison. The reason ESI comparison is done for multi-
homing, is to prevent false detection of MAC move among the PEs
attached to the same multi-homed site.
A PE receiving a MAC Advertisement route for a MAC address with a
different Ethernet segment identifier and a higher sequence number
than that which it had previously advertised, withdraws its MAC
Advertisement route. If two (or more) PEs advertise the same MAC
address with same sequence number but different Ethernet segment
identifiers, a PE that receives these routes selects the route
advertised by the PE with lowest IP address as the best route. If the
PE is the originator of the MAC route and it receives the same MAC
address with the same sequence number that it generated, it will
compare its own IP address with the IP address of the remote PE and
will select the lowest IP. If its own route is not the best one, it
will withdraw the route.
15.1. MAC Duplication Issue
A situation may arise where the same MAC address is learned by
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different PEs in the same VLAN because of two (or more hosts) being
mis-configured with the same (duplicate) MAC address. In such
situation, the traffic originating from these hosts would trigger
continuous MAC moves among the PEs attached to these hosts. It is
important to recognize such situation and avoid incrementing the
sequence number (in the MAC Mobility attribute) to infinity. In order
to remedy such situation, a PE that detects a MAC mobility event by
way of local learning starts an M-second timer (default value of M =
180) and if it detects N MAC moves before the timer expires (default
value for N = 5), it concludes that a duplicate MAC situation has
occurred. The PE MUST alert the operator and stop sending and
processing any BGP MAC Advertisement routes for that MAC address till
a corrective action is taken by the operator. The values of M and N
MUST be configurable to allow for flexibility in operator control.
Note that the other PEs in the E-VPN instance will forward the
traffic for the duplicate MAC address to one of the PEs advertising
the duplicate MAC address.
15.2. Sticky MAC addresses
There are scenarios in which it is desired to configure some MAC
addresses as static so that they are not subjected to MAC move. In
such scenarios, these MAC addresses are advertised with MAC Mobility
Extended Community where static flag is set to 1 and sequence number
is set to zero. If a PE receives such advertisements and later learns
the same MAC address(es) via local learning, then the PE MUST alert
the operator.
16. Multicast & Broadcast
The PEs in a particular EVPN instance may use ingress replication or
P2MP LSPs to send multicast traffic to other PEs.
16.1. Ingress Replication
The PEs may use ingress replication for flooding BUM traffic as
described in section "Handling of Multi-Destination Traffic". A given
broadcast packet must be sent to all the remote PEs. However a given
multicast packet for a multicast flow may be sent to only a subset of
the PEs. Specifically a given multicast flow may be sent to only
those PEs that have receivers that are interested in the multicast
flow. Determining which of the PEs have receivers for a given
multicast flow is done using explicit tracking described below.
16.2. P2MP LSPs
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A PE may use an "Inclusive" tree for sending an BUM packet. This
terminology is borrowed from [RFC7117].
A variety of transport technologies may be used in the SP network.
For inclusive P-Multicast trees, these transport technologies include
point-to-multipoint LSPs created by RSVP-TE or mLDP.
16.2.1. Inclusive Trees
An Inclusive Tree allows the use of a single multicast distribution
tree, referred to as an Inclusive P-Multicast tree, in the SP network
to carry all the multicast traffic from a specified set of EVPN
instances on a given PE. A particular P-Multicast tree can be set up
to carry the traffic originated by sites belonging to a single EVPN
instance, or to carry the traffic originated by sites belonging to
several EVPN instances. The ability to carry the traffic of more than
one EVPN instance on the same tree is termed 'Aggregation' and the
tree is called an Aggregate Inclusive P-Multicast tree or Aggregate
Inclusive tree for short. The Aggregate Inclusive tree needs to
include every PE that is a member of any of the EVPN instances that
are using the tree. This implies that a PE may receive BUM traffic
even if it doesn't have any receivers that are interested in
receiving that traffic.
An Inclusive or Aggregate Inclusive tree as defined in this document
is a P2MP tree. A P2MP tree is used to carry traffic only for EVPN
CEs that are connected to the PE that is the root of the tree.
The procedures for signaling an Inclusive tree are the same as those
in [RFC7117] with the VPLS-AD route replaced with the Inclusive
Multicast Ethernet Tag route. The P-Tunnel attribute [RFC7117] for an
Inclusive tree is advertised with the Inclusive Multicast Ethernet
Tag route as described in section "Handling of Multi-Destination
Traffic". Note that for an Aggregate Inclusive tree, a PE can
"aggregate" multiple EVPN instances on the same P2MP LSP using
upstream labels. The procedures for aggregation are the same as those
described in [RFC7117], with VPLS A-D routes replaced by EVPN
Inclusive Multicast Ethernet Tag routes.
17. Convergence
This section describes failure recovery from different types of
network failures.
17.1. Transit Link and Node Failures between PEs
The use of existing MPLS Fast-Reroute mechanisms can provide failure
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recovery in the order of 50ms, in the event of transit link and node
failures in the infrastructure that connects the PEs.
17.2. PE Failures
Consider a host CE1 that is dual homed to PE1 and PE2. If PE1 fails,
a remote PE, PE3, can discover this based on the failure of the BGP
session. This failure detection can be in the sub-second range if
BFD is used to detect BGP session failure. PE3 can update its
forwarding state to start sending all traffic for CE1 to only PE2.
17.3. PE to CE Network Failures
If the connectivity between the multi-homed CE and one of the PEs
that it is attached to, fails, the PE MUST withdraw the set of
Ethernet A-D per ES routes that had been previously advertised for
that ES. When the MAC entry on the PE ages out, the PE MUST withdraw
the MAC address from BGP. Note that to aid convergence, the Ethernet
A-D per EVI routes MAY be withdrawn before the MAC routes. This
enables the remote PEs to remove the MPLS next-hop to this particular
PE from the set of MPLS next-hops that can be used to forward traffic
to the CE.
When a Ethernet Tag is decommissioned on an Ethernet segment, then
the PE MUST withdraw the Ethernet A-D per EVI route(s) announced for
the <ESI, Ethernet Tags> that are impacted by the decommissioning. In
addition, the PE MUST also withdraw the MAC advertisement routes that
are impacted by the decommissioning.
The Ethernet A-D per ES routes should be used by an implementation to
optimize the withdrawal of MAC advertisement routes. When a PE
receives a withdrawal of a particular Ethernet A-D route from a PE it
SHOULD consider all the MAC advertisement routes, that are learned
from the same ESI as in the Ethernet A-D route, from the advertising
PE, as having been withdrawn. This optimizes the network convergence
times in the event of PE to CE failures.
18. Frame Ordering
In a MAC address, if the value of the 1st nibble (bits 8 thorough 5)
of the most significant octet of the destination MAC address (which
follows the last MPLS label) happens to be 0x4 or 0x6, then the
Ethernet frame can be misinterpreted as an IPv4 or IPv6 packet by
intermediate P nodes performing ECMP based on deep packet inspection,
thus resulting in load balancing packets belonging to the same flow
on different ECMP paths and subjecting them to different delays.
Therefore, packets belonging to the same flow can arrive at the
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destination out of order. This out of order delivery can happen
during steady state in absence of any failures resulting in
significant impact to the network operation.
In order to avoid any such mis-ordering, the following rules are
applied:
- If a network uses deep packet inspection for its ECMP, then the
"Preferred PW MPLS Control Word" per [RFC4385] SHOULD be used with
the value of 0 (e.g., a 4-octet field with value of zero) when
sending EVPN encapsulated packets over a MP2P LSP.
- If a network uses Entropy label [RFC6790], then the control word
SHOULD NOT be used when sending EVPN encapsulated packet over a MP2P
LSP.
- When sending EVPN encapsulated packets over a P2MP LSP or P2P LSP,
then the control world SHOULD NOT be used.
19. Acknowledgements
Special thanks to Yakov Rekhter for reviewing this draft several
times and providing valuable comments and for his very engaging
discussions on several topics of this draft that helped shape this
document. We would also like to thank Pedro Marques, Kaushik Ghosh,
Nischal Sheth, Robert Raszuk, Amit Shukla, and Nadeem Mohammed for
discussions that helped shape this document. We would also like to
thank Han Nguyen for his comments and support of this work. We would
also like to thank Steve Kensil and Reshad Rahman for their reviews.
We would like to thank Jorge Rabadan for his contribution to section
5 of this draft. We like to thank Thomas Morin for his review of this
draft and his contribution of section 8.6. Many thanks to Jakob Heitz
for his help to improve several sections of this draft.
We would also like to thank Clarence Filsfils, Dennis Cai, Quaizar
Vohra, Kireeti Kompella, Apurva Mehta for their contributions to this
document.
Last but not least, special thanks to Giles Heron (our WG chair) for
his detailed review of this document in preparation for WG LC and
making many valuable suggestions.
20. Security Considerations
Security considerations discussed in [RFC4761] and [RFC4762] apply to
this document for MAC learning in data-plane over an Attachment
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Circuit (AC) and for flooding of unknown unicast and ARP messages
over the MPLS/IP core. Security considerations discussed in [RFC4364]
apply to this document for MAC learning in control-plane over the
MPLS/IP core. This section describes additional considerations.
As mentioned in [RFC4761], there are two aspects to achieving data
privacy and protecting against denial-of-service attacks in a VPN:
securing the control plane and protecting the forwarding path.
Compromise of the control plane could result in a PE sending customer
data belonging to some EVPN to another EVPN, or black-holing EVPN
customer data, or even sending it to an eavesdropper; none of which
are acceptable from a data privacy point of view. In addition,
compromise of the control plane could result in black-holing EVPN
customer data and could provide opportunities for unauthorized EVPN
data usage (e.g., exploiting traffic replication within a multicast
tree to amplify a denial-of-service attack based on sending large
amounts of traffic).
The mechanisms in this document use BGP for the control plane. Hence,
techniques such as in [RFC5925] help authenticate BGP messages,
making it harder to spoof updates (which can be used to divert EVPN
traffic to the wrong EVPN instance) or withdrawals (denial-of-service
attacks). In the multi-AS methods (b) and (c), this also means
protecting the inter-AS BGP sessions, between the ASBRs, the PEs, or
the Route Reflectors.
Further discussion of security considerations for BGP may be found in
the BGP specification itself [RFC4271] and in the security analysis
for BGP [RFC4272]. The original discussion of the use of the TCP MD5
signature option to protect BGP sessions is found in [RFC5925], while
[RFC6952] includes an analysis of BGP keying and authentication
issues.
Note that [RFC5925] will not help in keeping MPLS labels private --
knowing the labels, one can eavesdrop on EVPN traffic. Such
eavesdropping additionally requires access to the data path within an
SP network. Users of VPN services are expected to take appropriate
precautions (such as encryption) to protect the data exchanged over a
VPN.
One of the requirements for protecting the data plane is that the
MPLS labels be accepted only from valid interfaces. For a PE, valid
interfaces comprise links from other routers in the PE's own AS. For
an ASBR, valid interfaces comprise links from other routers in the
ASBR's own AS, and links from other ASBRs in ASes that have instances
of a given EVPN. It is especially important in the case of multi-AS
EVPN instances that one accept EVPN packets only from valid
interfaces.
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It is also important to help limit malicious traffic into a network
for an imposter MAC address. The mechanism described in section 15.1,
shows how duplicate MAC addresses can be detected and continuous
false MAC mobility can be prevented. The mechanism described in
section 15.2 shows how MAC addresses can be pinned to a given
Ethernet Segment, such that if they appear behind any other Ethernet
Segments, the traffic for those MAC addresses can be prevented from
entering the EVPN network from the other Ethernet Segments.
21. Contributors
In addition to the authors listed on the front page, the following
individuals have also helped to shape this document:
Keyur Patel
Samer Salam
Sami Boutros
Cisco
Yakov Rekhter
Ravi Shekhar
Juniper Networks
Florin Balus
Nuage Networks
22. IANA Considerations
This document defines a new NLRI, called "EVPN", to be carried in BGP
using multiprotocol extensions. This NLRI uses the existing AFI of
25 (L2VPN). IANA has assigned it a SAFI value of 70.
IANA has allocated the following EVPN Extended Community sub-types in
[RFC7153] and this document is the only reference for them.
0x00 MAC Mobility [this document]
0x01 ESI Label [this document]
0x02 ES-Import Route Target [this document]
This document is creating a registry called "EVPN Route Types." New
registrations will be made through the "RFC Required" procedure
defined in [RFC5226]. The registry has a maximum value of 255.
Initial registrations are as follows:
0 RESERVED
1 Ethernet Auto-Discovery [this document]
2 MAC/IP Advertisement [this document]
3 Inclusive Multicast Ethernet Tag [this document]
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4 Ethernet Segment [this document]
23. References
23.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4364] Rosen, Rekhter, et. al., "BGP/MPLS IP VPNs", February 2006
[RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service
(VPLS) Using BGP for Auto-Discovery and Signaling", RFC
4761, January 2007.
[RFC4762] Lasserre, M. and V. Kompella, "Virtual Private LAN Service
(VPLS) Using Label Distribution Protocol (LDP) Signaling",
RFC 4762, January 2007.
[RFC4271] Y. Rekhter et. al., "A Border Gateway Protocol 4 (BGP-4)",
RFC 4271, January 2006
[RFC4760] T. Bates et. al., "Multiprotocol Extensions for BGP-4",
RFC 4760, January 2007
[RFC7153] E. Rosen et. al., "IANA Registries for BGP Extended
Communities", RFC 7153, March 2014
23.2 Informative References
[RFC7209] A. Sajassi, R. Aggarwal et. al., "Requirements for
Ethernet VPN", May 2014.
[RFC7117] R. Aggarwal et.al., "Multicast in Virtual Private LAN
Service (VPLS)", February 2014.
[RFC4684] P. Marques et. al., "Constrained Route Distribution for
Border Gateway Protocol/MultiProtocol Label Switching
(BGP/MPLS) Internet Protocol (IP) Virtual Private Networks
(VPNs)", RFC 4684, November 2006.
[RFC6790] K. Kompella et. al, "The Use of Entropy Labels in MPLS
Forwarding", RFC 6790, November 2012.
[RFC4385] S. Bryant et. al, "PWE3 Control Word for Use over an MPLS
PSN", RFC 4385, February 2006
[RFC5925] J. Touch et. al., "The TCP Authentication Option", RFC
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5925, June 2010
[RFC5226] T. Narten et. al., "Guidelines for Writing an IANA
Considerations Section in RFCs", RFC 5226, May 2008
[RFC4272] S. Murphy, "BGP Security Vulnerabilities Analysis", RFC
4272, January 2006
[RFC6952] M. Jethanandani et. al., "Analysis of BGP, LDP, PCEP, and
MSDP Issues According to the Keying and Authentication
for Routing Protocols (KARP) Design Guide", RFC 6952, May
2013
[802.1Q] "IEEE Standard for Local and metropolitan area networks -
Media Access Control (MAC) Bridges and Virtual Bridged
Local Area Networks", IEEE Std 802.1Q(tm), 2012 Edition,
October 2012.
24. Author's Address
Ali Sajassi
Cisco
Email: sajassi@cisco.com
Rahul Aggarwal
Email: raggarwa_1@yahoo.com
Nabil Bitar
Verizon Communications
Email : nabil.n.bitar@verizon.com
Aldrin Isaac
Bloomberg
Email: aisaac71@bloomberg.net
James Uttaro
AT&T
Email: uttaro@att.com
John Drake
Juniper Networks
Email: jdrake@juniper.net
Sajassi, et al. Expires April 18, 2015 [Page 51]
INTERNET DRAFT BGP MPLS Based Ethernet VPN October 18, 2014
Wim Henderickx
Alcatel-Lucent
e-mail: wim.henderickx@alcatel-lucent.com
Sajassi, et al. Expires April 18, 2015 [Page 52]
