Internet DRAFT - draft-ietf-bess-evpn-inter-subnet-forwarding
draft-ietf-bess-evpn-inter-subnet-forwarding
BESS WorkGroup A. Sajassi
Internet-Draft S. Salam
Intended status: Standards Track S. Thoria
Expires: January 27, 2022 Cisco Systems
J. Drake
Juniper
J. Rabadan
Nokia
July 26, 2021
Integrated Routing and Bridging in EVPN
draft-ietf-bess-evpn-inter-subnet-forwarding-15
Abstract
Ethernet VPN (EVPN) provides an extensible and flexible multi-homing
VPN solution over an MPLS/IP network for intra-subnet connectivity
among Tenant Systems and End Devices that can be physical or virtual.
However, there are scenarios for which there is a need for a dynamic
and efficient inter-subnet connectivity among these Tenant Systems
and End Devices while maintaining the multi-homing capabilities of
EVPN. This document describes an Integrated Routing and Bridging
(IRB) solution based on EVPN to address such requirements.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119] and RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on January 27, 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
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described in the Simplified BSD License.
Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
3. EVPN PE Model for IRB Operation . . . . . . . . . . . . . . . 6
4. Symmetric and Asymmetric IRB . . . . . . . . . . . . . . . . 7
4.1. IRB Interface and its MAC and IP addresses . . . . . . . 10
4.2. Operational Considerations . . . . . . . . . . . . . . . 12
5. Symmetric IRB Procedures . . . . . . . . . . . . . . . . . . 13
5.1. Control Plane - Advertising PE . . . . . . . . . . . . . 13
5.2. Control Plane - Receiving PE . . . . . . . . . . . . . . 14
5.3. Subnet route advertisement . . . . . . . . . . . . . . . 15
5.4. Data Plane - Ingress PE . . . . . . . . . . . . . . . . . 16
5.5. Data Plane - Egress PE . . . . . . . . . . . . . . . . . 17
6. Asymmetric IRB Procedures . . . . . . . . . . . . . . . . . . 17
6.1. Control Plane - Advertising PE . . . . . . . . . . . . . 17
6.2. Control Plane - Receiving PE . . . . . . . . . . . . . . 18
6.3. Data Plane - Ingress PE . . . . . . . . . . . . . . . . . 19
6.4. Data Plane - Egress PE . . . . . . . . . . . . . . . . . 19
7. Mobility Procedure . . . . . . . . . . . . . . . . . . . . . 20
7.1. Initiating a gratutious ARP upon a Move . . . . . . . . . 21
7.2. Sending Data Traffic without an ARP Request . . . . . . . 22
7.3. Silent Host . . . . . . . . . . . . . . . . . . . . . . . 24
8. BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1. Router's MAC Extended Community . . . . . . . . . . . . . 25
9. Operational Models for Symmetric Inter-Subnet Forwarding . . 25
9.1. IRB forwarding on NVEs for Tenant Systems . . . . . . . . 25
9.1.1. Control Plane Operation . . . . . . . . . . . . . . . 27
9.1.2. Data Plane Operation . . . . . . . . . . . . . . . . 28
9.2. IRB forwarding on NVEs for Subnets behind Tenant Systems 30
9.2.1. Control Plane Operation . . . . . . . . . . . . . . . 31
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9.2.2. Data Plane Operation . . . . . . . . . . . . . . . . 32
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 33
11. Security Considerations . . . . . . . . . . . . . . . . . . . 33
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 34
13.1. Normative References . . . . . . . . . . . . . . . . . . 34
13.2. Informative References . . . . . . . . . . . . . . . . . 35
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36
1. Terminology
AC: Attachment Circuit
ARP: Address Resolution Protocol
ARP table: A logical view of a forwarding table on a PE that
maintains an IP to MAC binding entry on an IP interface for both IPv4
and IPv6. These entries are learned through ARP/ND or through EVPN.
Broadcast Domain: As per [RFC7432], an EVI consists of a single or
multiple broadcast domains. In the case of VLAN-bundle and VLAN-
based service models (see [RFC7432]), a broadcast domain is
equivalent to an EVI. In the case of VLAN-aware bundle service
model, an EVI contains multiple broadcast domains. Also, in this
document, broadcast domain and subnet are equivalent terms and
wherever "subnet" is used, it means "IP subnet"
Broadcast Domain Route Target: refers to the Broadcast Domain
assigned Route Target [RFC4364]. In the case of VLAN-aware bundle
service model, all the broadcast domain instances in the MAC-VRF
share the same Route Target
Bridge Table: The instantiation of a broadcast domain in a MAC-VRF,
as per [RFC7432].
Ethernet NVO tunnel: refers to Network Virtualization Overlay tunnels
with Ethernet payload as specified for VxLAN in [RFC7348] and for
NVGRE in [RFC7637].
EVI: EVPN Instance spanning the NVE/PE devices that are participating
on that EVPN, as per [RFC7432].
EVPN: Ethernet Virtual Private Networks, as per [RFC7432].
IP NVO tunnel: it refers to Network Virtualization Overlay tunnels
with IP payload (no MAC header in the payload) as specified for GPE
in [I-D.ietf-nvo3-vxlan-gpe].
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IP-VRF: A Virtual Routing and Forwarding table for IP routes on an
NVE/PE. The IP routes could be populated by EVPN and IP-VPN address
families. An IP-VRF is also an instantiation of a layer 3 VPN in an
NVE/PE.
IRB: Integrated Routing and Bridging interface. It connects an IP-
VRF to a broadcast domain (or subnet).
MAC-VRF: A Virtual Routing and Forwarding table for Media Access
Control (MAC) addresses on an NVE/PE, as per [RFC7432]. A MAC-VRF is
also an instantiation of an EVI in an NVE/PE.
ND: Neighbor Discovery Protocol
NVE: Network Virtualization Edge
NVGRE: Network Virtualization Generic Routing Encapsulation,
[RFC7637]
NVO: Network Virtualization Overlays
RT-2: EVPN route type 2, i.e., MAC/IP Advertisement route, as defined
in [RFC7432]
RT-5: EVPN route type 5, i.e., IP Prefix route. As defined in
Section 3 of [I-D.ietf-bess-evpn-prefix-advertisement]
TS: Tenant System
VA: Virtual Appliance
VNI: Virtual Network Identifier. As in [RFC8365], the term is used
as a representation of a 24-bit NVO instance identifier, with the
understanding that VNI will refer to a VXLAN Network Identifier in
VXLAN, or Virtual Subnet Identifier in NVGRE, etc. unless it is
stated otherwise.
VTEP: VXLAN Termination End Point, as in [RFC7348].
VXLAN: Virtual Extensible LAN, as in [RFC7348].
This document also assumes familiarity with the terminology of
[RFC7432], [RFC8365] and [RFC7365].
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2. Introduction
EVPN [RFC7432] provides an extensible and flexible multi-homing VPN
solution over an MPLS/IP network for intra-subnet connectivity among
Tenant Systems (TSes) and End Devices that can be physical or
virtual; where an IP subnet is represented by an EVPN Instance (EVI)
for a VLAN-based service or by an (EVI, VLAN) for a VLAN-aware bundle
service. However, there are scenarios for which there is a need for
a dynamic and efficient inter-subnet connectivity among these Tenant
Systems and End Devices while maintaining the multi-homing
capabilities of EVPN. This document describes an Integrated Routing
and Bridging (IRB) solution based on EVPN to address such
requirements.
The inter-subnet communication is traditionally achieved at
centralized L3 Gateway (L3GW) devices where all the inter-subnet
forwarding is performed and all the inter-subnet communication
policies are enforced. When two TSes belonging to two different
subnets connected to the same PE wanted to communicate with each
other, their traffic needed to be backhauled from the PE all the way
to the centralized gateway where inter-subnet switching is performed
and then back to the PE. For today's large multi-tenant data center,
this scheme is very inefficient and sometimes impractical.
In order to overcome the drawback of the centralized layer-3 GW
approach, IRB functionality is needed on the PEs (also referred to as
EVPN NVEs) attached to TSes in order to avoid inefficient forwarding
of tenant traffic (i.e., avoid back-hauling and hair-pinning). When
a PE with IRB capability receives tenant traffic over an Attachment
Circuit (AC), it can not only locally bridge the tenant intra-subnet
traffic but also can locally route the tenant inter-subnet traffic on
a packet by packet basis thus meeting the requirements for both intra
and inter-subnet forwarding and avoiding non-optimal traffic
forwarding associated with centralized layer-3 GW approach.
Some TSes run non-IP protocols in conjunction with their IP traffic.
Therefore, it is important to handle both kinds of traffic optimally
- e.g., to bridge non-IP and intra-subnet traffic and to route inter-
subnet IP traffic. Therefore, the solution needs to meet the
following requirements:
R1: The solution must provide each tenant with IP routing of its
inter-subnet traffic and Ethernet bridging of its intra-subnet
traffic and non-routable traffic, where non-routable traffic refers
both to non-IP traffic and IP traffic whose version differs from the
IP version configured in the IP-VRF. For example, if an IP-VRF in a
NVE is configured for IPv6 and that NVE receives IPv4 traffic on the
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corresponding VLAN, then the IPv4 traffic is treated as non-routable
traffic.
R2: The solution must allow IP routing of inter-subnet traffic to be
disabled on a per-VLAN basis on those PEs that are backhauling that
traffic to another PE for routing.
3. EVPN PE Model for IRB Operation
Since this document discusses IRB operation in relationship to EVPN
MAC-VRF, IP-VRF, EVI, Broadcast Domain, Bridge Table, and IRB
interfaces, it is important to understand the relationship between
these components. Therefore, the following PE model is illustrated
below to a) describe these components and b) illustrate the
relationship among them.
+-------------------------------------------------------------+
| |
| +------------------+ IRB PE |
| Attachment | +------------------+ |
| Circuit(AC1) | | +----------+ | MPLS/NVO tnl
----------------------*Bridge | | +-----
| | | |Table(BT1)| | +-----------+ / \ \
| | | | *---------* |<--> |Eth|
| | | | VLAN x | |IRB1| | \ / /
| | | +----------+ | | | +-----
| | | ... | | IP-VRF1 | |
| | | +----------+ | | RD2/RT2 |MPLS/NVO tnl
| | | |Bridge | | | | +-----
| | | |Table(BT2)| |IRB2| | / \ \
| | | | *---------* |<--> |IP |
----------------------* VLAN y | | +-----------+ \ / /
| AC2 | | +----------+ | +-----
| | | MAC-VRF1 | |
| +-+ RD1/RT1 | |
| +------------------+ |
| |
| |
+-------------------------------------------------------------+
Figure 1: EVPN IRB PE Model
A tenant needing IRB services on a PE, requires an IP Virtual Routing
and Forwarding table (IP-VRF) along with one or more MAC Virtual
Routing and Forwarding tables (MAC-VRFs). An IP-VRF, as defined in
[RFC4364], is the instantiation of an IPVPN instance in a PE. A MAC-
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VRF, as defined in [RFC7432], is the instantiation of an EVI (EVPN
Instance) in a PE. A MAC-VRF consists of one or more bridge tables,
where each bridge table corresponds to a VLAN (broadcast domain). If
service interfaces for an EVPN PE are configured in VLAN- Based mode
(i.e., section 6.1 of RFC7432), then there is only a single bridge
table per MAC-VRF (per EVI) - i.e., there is only one tenant VLAN per
EVI. However, if service interfaces for an EVPN PE are configured in
VLAN-Aware Bundle mode (i.e., section 6.3 of RFC7432), then there are
several bridge tables per MAC-VRF (per EVI) - i.e., there are several
tenant VLANs per EVI.
Each bridge table is connected to an IP-VRF via an L3 interface
called IRB interface. Since a single tenant subnet is typically (and
in this document) represented by a VLAN (and thus supported by a
single bridge table), for a given tenant there are as many bridge
tables as there are subnets and thus there are also as many IRB
interfaces between the tenant IP-VRF and the associated bridge tables
as shown in the PE model above.
IP-VRF is identified by its corresponding route target and route
distinguisher and MAC-VRF is also identified by its corresponding
route target and route distinguisher. If operating in EVPN VLAN-
Based mode, then a receiving PE that receives an EVPN route with MAC-
VRF route target can identify the corresponding bridge table;
however, if operating in EVPN VLAN-Aware Bundle mode, then the
receiving PE needs both the MAC-VRF route target and VLAN ID in order
to identify the corresponding bridge table.
4. Symmetric and Asymmetric IRB
This document defines and describes two types of IRB solutions -
namely symmetric and asymmetric IRB. The description of symmetric
and asymmetric IRB procedures relating to data path operations and
tables in this document is a logical view of data path lookups and
related tables. Actual implementations, while following this logical
view, may not strictly adhere to it for performance tradeoffs.
Specifically,
o References to ARP table in the context of asymmetric IRB is a
logical view of a forwarding table that maintains an IP to MAC
binding entry on a layer 3 interface for both IPv4 and IPv6.
These entries are not subject to ARP or ND protocol. For IP to
MAC bindings learnt via EVPN, an implementation may choose to
import these bindings directly to the respective forwarding table
(such as an adjacency/next-hop table) as opposed to importing them
to ARP or ND protocol tables.
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o References to host IP lookup followed by a host MAC lookup in the
context of asymmetric IRB MAY be collapsed into a single IP lookup
in a hardware implementation.
In symmetric IRB as its name implies, the lookup operation is
symmetric at both ingress and egress PEs - i.e., both ingress and
egress PEs perform lookups on both MAC and IP addresses. The ingress
PE performs a MAC lookup followed by an IP lookup and the egress PE
performs an IP lookup followed by a MAC lookup as depicted in the
following figure.
Ingress PE Egress PE
+-------------------+ +------------------+
| | | |
| +-> IP-VRF ----|---->---|-----> IP-VRF -+ |
| | | | | |
| BT1 BT2 | | BT3 BT2 |
| | | | | |
| ^ | | v |
| | | | | |
+-------------------+ +------------------+
^ |
| |
TS1->-+ +->-TS2
Figure 2: Symmetric IRB
In symmetric IRB as shown in figure-2, the inter-subnet forwarding
between two PEs is done between their associated IP-VRFs. Therefore,
the tunnel connecting these IP-VRFs can be either IP-only tunnel
(e.g., in case of MPLS or GPE encapsulation) or Ethernet NVO tunnel
(e.g., in case of VxLAN encapsulation). If it is an Ethernet NVO
tunnel, the TS1's IP packet is encapsulated in an Ethernet header
consisting of ingress and egress PEs MAC addresses - i.e., there is
no need for ingress PE to use the destination TS2's MAC address.
Therefore, in symmetric IRB, there is no need for the ingress PE to
maintain ARP entries for destination TS2's IP and MAC addresses
association in its ARP table. Each PE participating in symmetric IRB
only maintains ARP entries for locally connected hosts and maintains
MAC-VRFs/bridge tables for only locally configured subnets.
In asymmetric IRB, the lookup operation is asymmetric and the ingress
PE performs three lookups; whereas the egress PE performs a single
lookup - i.e., the ingress PE performs a MAC lookup, followed by an
IP lookup, followed by a MAC lookup again; whereas, the egress PE
performs just a single MAC lookup as depicted in figure 3 below.
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Ingress PE Egress PE
+-------------------+ +------------------+
| | | |
| +-> IP-VRF -> | | IP-VRF |
| | | | | |
| BT1 BT2 | | BT3 BT2 |
| | | | | | | |
| | +--|--->----|--------------+ | |
| | | | v |
+-------------------+ +----------------|-+
^ |
| |
TS1->-+ +->-TS2
Figure 3: Asymmetric IRB
In asymmetric IRB as shown in figure-3, the inter-subnet forwarding
between two PEs is done between their associated MAC-VRFs/bridge
tables. Therefore, the MPLS or NVO tunnel used for inter-subnet
forwarding MUST be of type Ethernet. Since only MAC lookup is
performed at the egress PE (e.g., no IP lookup), the TS1's IP packets
need to be encapsulated with the destination TS2's MAC address. In
order for ingress PE to perform such encapsulation, it needs to
maintain TS2's IP and MAC address association in its ARP table.
Furthermore, it needs to maintain destination TS2's MAC address in
the corresponding bridge table even though it may not have any TSes
of the corresponding subnet locally attached. In other words, each
PE participating in asymmetric IRB MUST maintain ARP entries for
remote hosts (hosts connected to other PEs) as well as maintain MAC-
VRFs/bridge tables and IRB interfaces for ALL subnets in an IP VRF
including subnets that may not be locally attached. Therefore,
careful consideration of PE scale aspects for its ARP table size, its
IRB interfaces, number and size of its bridge tables should be given
for the application of asymmetric IRB.
It should be noted that whenever a PE performs a host IP lookup for a
packet that is routed, IPv4 TTL or IPv6 hop limit for that packet is
decremented by one and if it reaches zero, the packet is discarded.
In the case of symmetric IRB, the TTL/hop limit is decremented by
both ingress and egress PEs (once by each); whereas, in the case of
asymmetric IRB, the TTL/hop limit is decremented only once by the
ingress PE.
The following sections define the control and data plane procedures
for symmetric and asymmetric IRB on ingress and egress PEs. The
following figure is used to describe these procedures, showing a
single IP-VRF and a number of broadcast domains on each PE for a
given tenant. I.e., an IP-VRF connects one or more EVIs, each EVI
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contains one MAC-VRF, each MAC VRF consists of one or more bridge
tables, one per broadcast domain, and a PE has an associated IRB
interface for each broadcast domain.
PE 1 +---------+
+-------------+ | |
TS1-----| MACx| | | PE2
(IP1/M1) |(BT1) | | | +-------------+
TS5-----| \ | | MPLS/ | |MACy (BT3) |-----TS3
(IP5/M5) |IPx/Mx \ | | VxLAN/ | | / | (IP3/M3)
| (IP-VRF1)|----| NVGRE |---|(IP-VRF1) |
| / | | | | \ |
TS2-----|(BT2) / | | | | (BT1) |-----TS4
(IP2/M2) | | | | | | (IP4/M4)
+-------------+ | | +-------------+
| |
+---------+
Figure 4: IRB forwarding
4.1. IRB Interface and its MAC and IP addresses
To support inter-subnet forwarding on a PE, the PE acts as an IP
Default Gateway from the perspective of the attached Tenant Systems
where default gateway MAC and IP addresses are configured on each IRB
interface associated with its subnet and falls into one of the
following two options:
1. All the PEs for a given tenant subnet use the same anycast
default gateway IP and MAC addresses. On each PE, this default
gateway IP and MAC addresses correspond to the IRB interface
connecting the bridge table associated with the tenant's VLAN to
the corresponding tenant's IP-VRF.
2. Each PE for a given tenant subnet uses the same anycast default
gateway IP address but its own MAC address. These MAC addresses
are aliased to the same anycast default gateway IP address
through the use of the Default Gateway extended community as
specified in [RFC7432], which is carried in the EVPN MAC/IP
Advertisement routes. On each PE, this default gateway IP
address along with its associated MAC addresses correspond to the
IRB interface connecting the bridge table associated with the
tenant's VLAN to the corresponding tenant's IP-VRF.
It is worth noting that if the applications that are running on the
TSes are employing or relying on any form of MAC security, then the
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first option (i.e. using anycast MAC address) should be used to
ensure that the applications receive traffic from the same IRB
interface MAC address that they are sending to. If the second option
is used, then the IRB interface MAC address MUST be the one used in
the initial ARP reply or ND Neighbor Advertisement (NA)for that TS.
Although both of these options are applicable to both symmetric and
asymmetric IRB, the option-1 is recommended because of the ease of
anycast MAC address provisioning on not only the IRB interface
associated with a given subnet across all the PEs corresponding to
that VLAN but also on all IRB interfaces associated with all the
tenant's subnets across all the PEs corresponding to all the VLANs
for that tenant. Furthermore, it simplifies the operation as there
is no need for Default Gateway extended community advertisement and
its associated MAC aliasing procedure. Yet another advantage is that
following host mobility, the host does not need to refresh the
default GW ARP/ND entry.
If option-1 is used, an implementation MAY choose to auto-derive the
anycast MAC address. If auto-derivation is used, the anycast MAC
MUST be auto-derived out of the following ranges (which are defined
in [RFC5798]):
o Anycast IPv4 IRB case: 00-00-5E-00-01-{VRID}
o Anycast IPv6 IRB case: 00-00-5E-00-02-{VRID}
Where the last octet is generated based on a configurable Virtual
Router ID (VRID, range 1-255)). If not explicitly configured, the
default value for the VRID octet is '1'. Auto-derivation of the
anycast MAC can only be used if there is certainty that the auto-
derived MAC does not collide with any customer MAC address.
In addition to IP anycast addresses, IRB interfaces can be configured
with non-anycast IP addresses for the purpose of OAM (such as
traceroute/ping to these interfaces) for both symmetric and
asymmetric IRB. These IP addresses need to be distributed as VPN
routes when PEs operate in symmetric IRB mode. However, they don't
need to be distributed if the PEs are operating in asymmetric IRB
mode as the non-anycast IP addresses are configured along with their
individual MACs and they get distributed via EVPN route type-2
advertisement.
For option-1, irrespective of using only the anycast MAC address or
both anycast and non-anycast MAC addresses (where the latter one is
used for the purpose of OAM) on the same IRB, when a TS sends an ARP
request or ND Neighbor Solicitation (NS) to the PE that is attached
to, the request is sent for the anycast IP address of the IRB
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interface associated with the TS's subnet and then the reply will use
anycast MAC address (in both Source MAC in the Ethernet header and
Sender hardware address in the payload). For example, in figure 4,
TS1 is configured with the anycast IPx address as its default gateway
IP address and thus when it sends an ARP request for IPx (anycast IP
address of the IRB interface for BT1), the PE1 sends an ARP reply
with the MACx which is the anycast MAC address of that IRB interface.
Traffic routed from IP-VRF1 to TS1 uses the anycast MAC address as
source MAC address.
4.2. Operational Considerations
Symmetric and Asymmetric IRB modes may coexist in the same network,
and an ingress PE that supports both forwarding modes for a given
tenant can interwork with egress PEs that support either IRB mode.
The egress PE will indicate the desired forwarding mode for a given
host based on the presence of the Label2 field and the IP-VRF route-
target in the EVPN MAC/IP Advertisement route. If the Label2 field
of the received MAC/IP Advertisement route for host H1 is non-zero,
and one of its route-targets identifies the IP-VRF, the ingress PE
will use Symmetric IRB mode when forwarding packets destined to H1.
If the Label2 field is zero and the MAC/IP Advertisement route for H1
does not carry any route-target that identifies the IP-VRF, the
ingress PE will use Asymmetric mode when forwarding traffic to H1.
As an example that illustrates the previous statement, suppose PE1
and PE2 need to forward packets from TS2 to TS4 in the example of
Figure 4. Since both PEs are attached to the bridge table of the
destination host, Symmetric and Asymmetric IRB modes are both
possible as long as the ingress PE, PE1, supports both modes. The
forwarding mode will depend on the mode configured in the egress PE,
PE2. That is:
1. If PE2 is configured for Symmetric IRB mode, PE2 will advertise
TS4 MAC/IP addresses in a MAC/IP Advertisement route with a non-
zero Label2 field, e.g., Label2=Lx, and a route-target that
identifies IP-VRF1 in PE1. IP4 will be installed in PE1's IP-
VRF1, TS4's ARP and MAC information will also be installed in
PE1's IRB interface ARP table and BT1 respectively. When a
packet from TS2 destined to TS4 is looked up in PE1's IP-VRF
route-table, a longest prefix match lookup will find IP4 in the
IP-VRF, and PE1 will forward using the Symmetric IRB mode and
Label Lx.
2. However, if PE2 is configured for Asymmetric IRB mode, PE2 will
advertise TS4 MAC/IP information in a MAC/IP Advertisement route
with a zero Label2 field and no route-target identifying IP-VRF1.
In this case, PE2 will install TS4 information in its ARP table
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and BT1. When a packet from TS2 to TS4 arrives at PE1, a longest
prefix match on IP-VRF1's route-table will yield the local IRB
interface to BT1, where a subsequent ARP and bridge table lookup
will provide the information for an Asymmetric forwarding mode to
PE2.
Refer to [I-D.ietf-bess-evpn-modes-interop] for more information
about interoperability between Symmetric and Asymmetric forwarding
modes.
The choice between Symmetric or Asymmetric mode is based on the
operator's preference and it is a trade-off between scale (better in
the Symmetric IRB mode) and control plane simplicity (Asymmetric IRB
mode simplifies the control plane). In cases where a tenant has
hosts for every subnet attached to all (or most) the PEs, the ARP and
MAC entries need to be learned by all PEs anyway and therefore the
Asymmetric IRB mode simplifies the forwarding model and saves space
in the IP-VRF route-table, since host routes are not installed in the
route-table. However, if the tenant does not need to stretch subnets
(broadcast domains) to multiple PEs and inter-subnet-forwarding is
needed, the Symmetric IRB model will save ARP and bridge table space
in all the PEs (in comparison with the Asymmetric IRB model).
5. Symmetric IRB Procedures
5.1. Control Plane - Advertising PE
When a PE (e.g., PE1 in figure 4 above) learns MAC and IP address of
a TS (e.g., via an ARP request or Neighbor Solicitation), it adds the
MAC address to the corresponding MAC-VRF/bridge table of that
tenant's subnet and adds the IP address to the IP-VRF for that
tenant. Furthermore, it adds this TS's MAC and IP address
association to its ARP table or NDP cache. It then builds an EVPN
MAC/IP Advertisement route (type 2) as follows and advertises it to
other PEs participating in that tenant's VPN.
o The Length field of the BGP EVPN NLRI for an EVPN MAC/IP
Advertisement route MUST be either 40 (if IPv4 address is carried)
or 52 (if IPv6 address is carried).
o Route Distinguisher (RD), Ethernet Segment Identifier, Ethernet
Tag ID, MAC Address Length, MAC Address, IP Address Length, IP
Address, and MPLS Label1 fields MUST be set per [RFC7432] and
[RFC8365].
o The MPLS Label2 field is set to either an MPLS label or a VNI
corresponding to the tenant's IP-VRF. In the case of an MPLS
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label, this field is encoded as 3 octets, where the high-order 20
bits contain the label value.
Just as in [RFC7432], the RD, Ethernet Tag ID, MAC Address Length,
MAC Address, IP Address Length, and IP Address fields are part of the
route key used by BGP to compare routes. The rest of the fields are
not part of the route key.
This route is advertised along with the following two extended
communities:
1. Encapsulation Extended Community
2. Router's MAC Extended Community
This route is advertised with one or more Encapsulation extended
communities [RFC9012], one for each encapsulation type supported by
the advertising PE. If one or more encapsulation types require an
Ethernet frame, a single Router's MAC extended community, section
8.1, is also advertised. This extended community specifies the MAC
address to be used as the inner destination MAC address in an
Ethernet frame sent to the advertising PE.
This route MUST be advertised with two route targets, one
corresponding to the MAC-VRF of the tenant's subnet and another
corresponding to the tenant's IP-VRF.
5.2. Control Plane - Receiving PE
When a PE (e.g., PE2 in figure 4 above) receives this EVPN MAC/IP
Advertisement route, it performs the following:
o The MAC-VRF route target and Ethernet Tag, if the latter is non-
zero, are used to identify the correct MAC-VRF and bridge table
and if they are found the MAC address is imported. The IP-VRF
route target is used to identify the correct IP-VRF and if it is
found the IP address is imported.
If the MPLS label2 field is non-zero, it means that this route is to
be used for symmetric IRB and the MPLS label2 value is to be used
when sending a packet for this IP address to the advertising PE.
If the receiving PE receives this route with both the MAC-VRF and IP-
VRF route targets but the MAC/IP Advertisement route does not include
MPLS label2 field and if the receiving PE supports asymmetric IRB
mode, then the receiving PE installs the MAC address in the
corresponding MAC-VRF and (IP, MAC) association in the ARP table for
that tenant (identified by the corresponding IP-VRF route target).
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If the receiving PE receives this route with both the MAC-VRF and IP-
VRF route targets and if the receiving PE does not support either
asymmetric or symmetric IRB modes, then if it has the corresponding
MAC-VRF, it only imports the MAC address.
If the receiving PE receives this route with both the MAC-VRF and IP-
VRF route targets and the MAC/IP Advertisement route includes MPLS
label2 field but the receiving PE only supports asymmetric IRB mode,
then the receiving PE MUST ignore MPLS label2 field and install the
MAC address in the corresponding MAC-VRF and (IP, MAC) association in
the ARP table for that tenant (identified by the corresponding IP-VRF
route target).
5.3. Subnet route advertisement
In the case of symmetric IRB, a layer-3 subnet and IRB interface
corresponding to a MAC-VRF/bridge table is required to be provisioned
at a PE only if that PE has locally attached hosts in that subnet.
In order to enable inter-subnet routing across PEs in a deployment
where not all subnets are provisioned at all PEs participating in an
EVPN IRB instance, PEs MUST advertise local subnet routes as EVPN RT-
5. These subnet routes are required for bootstrapping host (MAC,IP)
learning using gleaning procedures initiated by an inter-subnet data
packet.
I.e., if a given host's (MAC, IP) association is unknown, and an
ingress PE needs to send a packet to that host, then that ingress PE
needs to know which egress PEs are attached to the subnet in which
the host resides in order to send the packet to one of those PEs,
causing the PE receiving the packet to probe for that host. For
example, Consider a subnet A that is locally attached to PE1 and
subnet B that is locally attached to PE2 and to PE3. Host A in
subnet A, that is attached to PE1 initiates a data packet destined to
host B in subnet B that is attached to PE3. If host B's (MAC, IP)
has not yet been learnt either via a gratuitous ARP OR via a prior
gleaning procedure, a new gleaning procedure MUST be triggered for
host B's (MAC, IP) to be learnt and advertised across the EVPN
network. Since host B's subnet is not local to PE1, an IP lookup for
host B at PE1 will not trigger this gleaning procedure for host B's
(MAC, IP). Therefore, PE1 MUST learn subnet B's prefix route via
EVPN RT-5 advertised from PE2 and PE3, so it can route the packet to
one of the PEs that have subnet B locally attached. Once the packet
is received at PE2 OR PE3, and the route lookup yields a glean
result, an ARP request is triggered and flooded across the layer-2
overlay. This ARP request would be received and replied to by host
B, resulting in host B (MAC, IP) learning at PE3, and its
advertisement across the EVPN network. Packets from host A to host B
can now be routed directly from PE1 to PE3. Advertisement of local
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subnet EVPN RT-5 for an IP VRF MAY typically be achieved via
provisioning connected route redistribution to BGP.
5.4. Data Plane - Ingress PE
When an Ethernet frame is received by an ingress PE (e.g., PE1 in
figure 4 above), the PE uses the AC ID (e.g., VLAN ID) to identify
the associated MAC-VRF/bridge table and it performs a lookup on the
destination MAC address. If the MAC address corresponds to its IRB
Interface MAC address, the ingress PE deduces that the packet must be
inter-subnet routed. Hence, the ingress PE performs an IP lookup in
the associated IP-VRF table. The lookup identifies BGP next hop of
egress PE along with the tunnel/encapsulation type and the associated
MPLS/VNI values. The ingress PE also decrements the TTL/hop limit
for that packet by one and if it reaches zero, the ingress PE
discards the packet.
If the tunnel type is that of MPLS or IP-only NVO tunnel, then TS's
IP packet is sent over the tunnel without any Ethernet header.
However, if the tunnel type is that of Ethernet NVO tunnel, then an
Ethernet header needs to be added to the TS's IP packet. The source
MAC address of this inner Ethernet header is set to the ingress PE's
router MAC address and the destination MAC address of this inner
Ethernet header is set to the egress PE's router MAC address learnt
via Router's MAC extended community attached to the route. MPLS VPN
label is set to the received label2 in the route. In the case of
Ethernet NVO tunnel type, VNI may be set one of two ways:
o downstream mode: VNI is set to the received label2 in the route
which is downstream assigned.
o global mode: VNI is set to the received label2 in the route which
is domain-wide assigned. This VNI value from received label2 MUST
be the same as the locally configured VNI for the IP VRF as all
PEs in the NVO MUST be configured with the same IP VRF VNI for
this mode of operation. If the received label2 value does not
match the locally configured VNI value the route MUST NOT be used
and an error message SHOULD logged.
PEs may be configured to operate in one of these two modes depending
on the administrative domain boundaries across PEs participating in
the NVO, and PE's capability to support downstream VNI mode.
In the case of NVO tunnel encapsulation, the outer source and
destination IP addresses are set to the ingress and egress PE BGP
next-hop IP addresses respectively.
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5.5. Data Plane - Egress PE
When the tenant's MPLS or NVO encapsulated packet is received over an
MPLS or NVO tunnel by the egress PE, the egress PE removes NVO tunnel
encapsulation and uses the VPN MPLS label (for MPLS encapsulation) or
VNI (for NVO encapsulation) to identify the IP-VRF in which IP lookup
needs to be performed. If the VPN MPLS label or VNI identifies a
MAC- VRF instead of an IP-VRF, then the procedures in section 6.4 for
asymmetric IRB are executed.
The lookup in the IP-VRF identifies a local adjacency to the IRB
interface associated with the egress subnet's MAC-VRF/bridge table.
The egress PE also decrements the TTL/hop limit for that packet by
one and if it reaches zero, the egress PE discards the packet.
The egress PE gets the destination TS's MAC address for that TS's IP
address from its ARP table or NDP cache, it encapsulates the packet
with that destination MAC address and a source MAC address
corresponding to that IRB interface and sends the packet to its
destination subnet MAC-VRF/bridge table.
The destination MAC address lookup in the MAC-VRF/bridge table
results in local adjacency (e.g., local interface) over which the
Ethernet frame is sent on.
6. Asymmetric IRB Procedures
6.1. Control Plane - Advertising PE
When a PE (e.g., PE1 in figure 4 above) learns MAC and IP address of
an attached TS (e.g., via an ARP request or ND Neighbor
Solicitation), it populates its MAC-VRF/bridge table, IP-VRF, and ARP
table or NDP cache just as in the case for symmetric IRB. It then
builds an EVPN MAC/IP Advertisement route (type 2) as follows and
advertises it to other PEs participating in that tenant's VPN.
o The Length field of the BGP EVPN NLRI for an EVPN MAC/IP
Advertisement route MUST be either 37 (if IPv4 address is carried)
or 49 (if IPv6 address is carried).
o Route Distinguisher (RD), Ethernet Segment Identifier, Ethernet
Tag ID, MAC Address Length, MAC Address, IP Address Length, IP
Address, and MPLS Label1 fields MUST be set per [RFC7432] and
[RFC8365].
o The MPLS Label2 field MUST NOT be included in this route.
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Just as in [RFC7432], the RD, Ethernet Tag ID, MAC Address Length,
MAC Address, IP Address Length, and IP Address fields are part of the
route key used by BGP to compare routes. The rest of the fields are
not part of the route key.
This route is advertised along with the following extended community:
o Tunnel Type Extended Community
For asymmetric IRB mode, Router's MAC extended community is not
needed because forwarding is performed using destination TS's MAC
address which is carried in this EVPN route type-2 advertisement.
This route MUST always be advertised with the MAC-VRF route target.
It MAY also be advertised with a second route target corresponding to
the IP-VRF.
6.2. Control Plane - Receiving PE
When a PE (e.g., PE2 in figure 4 above) receives this EVPN MAC/IP
Advertisement route, it performs the following:
o Using MAC-VRF route target, it identifies the corresponding MAC-
VRF and imports the MAC address into it. For asymmetric IRB mode,
it is assumed that all PEs participating in a tenant's VPN are
configured with all subnets (i.e., all VLANs) and corresponding
MAC-VRFs/bridge tables even if there are no locally attached TSes
for some of these subnets. The reason for this is because ingress
PE needs to do forwarding based on destination TS's MAC address
and perform NVO tunnel encapsulation as a property of a lookup in
MAC-VRF/bridge table.
o If only MAC-VRF route target is used, then the receiving PE uses
the MAC-VRF route target to identify the corresponding IP-VRF --
i.e., many MAC-VRF route targets map to the same IP-VRF for a
given tenant. In this case, MAC-VRF may be used by the receiving
PE to identify the corresponding IP VRF via the IRB interface
associated with the subnet MAC-VRF/bridge table. In this case,
the MAC-VRF route target may be used by the receiving PE to
identify the corresponding IP VRF.
o Using MAC-VRF route target, the receiving PE identifies the
corresponding ARP table or NDP cache for the tenant and it adds an
entry to the ARP table or NDP cache for the TS's MAC and IP
address association. It should be noted that the tenant's ARP
table or NDP cache at the receiving PE is identified by all the
MAC- VRF route targets for that tenant.
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o If IP-VRF route target is included, it may be used to import the
route to IP-VRF. If IP-VRF route-target is not included, MAC-VRF
is used to derive corresponding IP-VRF for import, as explained in
the prior section. In both cases, IP-VRF route is installed with
the TS MAC binding included in the received route.
If the receiving PE receives the MAC/IP Advertisement route with MPLS
label2 field but the receiving PE only supports asymmetric IRB mode,
then the receiving PE MUST ignore MPLS label2 field and install the
MAC address in the corresponding MAC-VRF and (IP, MAC) association in
the ARP table or NDP cache for that tenant (with IRB interface
identified by the MAC-VRF).
6.3. Data Plane - Ingress PE
When an Ethernet frame is received by an ingress PE (e.g., PE1 in
figure 4 above), the PE uses the AC ID (e.g., VLAN ID) to identify
the associated MAC-VRF/bridge table and it performs a lookup on the
destination MAC address. If the MAC address corresponds to its IRB
Interface MAC address, the ingress PE deduces that the packet must be
inter-subnet routed. Hence, the ingress PE performs an IP lookup in
the associated IP-VRF table. The lookup identifies a local adjacency
to the IRB interface associated with the egress subnet's MAC-VRF/
bridge table. The ingress PE also decrements the TTL/hop limit for
that packet by one and if it reaches zero, the ingress PE discards
the packet.
The ingress PE gets the destination TS's MAC address for that TS's IP
address from its ARP table or NDP cache, it encapsulates the packet
with that destination MAC address and a source MAC address
corresponding to that IRB interface and sends the packet to its
destination subnet MAC-VRF/bridge table.
The destination MAC address lookup in the MAC-VRF/bridge table
results in BGP next hop address of egress PE along with label1 (L2
VPN MPLS label or VNI). The ingress PE encapsulates the packet using
Ethernet NVO tunnel of the choice (e.g., VxLAN or NVGRE) and sends
the packet to the egress PE. Because the packet forwarding is
between ingress PE's MAC-VRF/bridge table and egress PE's MAC-VRF/
bridge table, the packet encapsulation procedures follow that of
[RFC7432] for MPLS and [RFC8365] for VxLAN encapsulations.
6.4. Data Plane - Egress PE
When a tenant's Ethernet frame is received over an NVO tunnel by the
egress PE, the egress PE removes NVO tunnel encapsulation and uses
the VPN MPLS label (for MPLS encapsulation) or VNI (for NVO
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encapsulation) to identify the MAC-VRF/bridge table in which MAC
lookup needs to be performed.
The MAC lookup results in local adjacency (e.g., local interface)
over which the packet needs to get sent.
Note that the forwarding behavior on the egress PE is the same as
EVPN intra-subnet forwarding described in [RFC7432] for MPLS and
[RFC8365] for NVO networks. In other words, all the packet
processing associated with the inter-subnet forwarding semantics is
confined to the ingress PE for asymmetric IRB mode.
It should also be noted that [RFC7432] provides a different level of
granularity for the EVPN label. Besides identifying the bridge
domain table, it can be used to identify the egress interface or a
destination MAC address on that interface. If EVPN label is used for
egress interface or individual MAC address identification, then no
MAC lookup is needed in the egress PE for MPLS encapsulation and the
packet can be directly forwarded to the egress interface just based
on EVPN label lookup.
7. Mobility Procedure
When a TS moves from one NVE (aka source NVE) to another NVE (aka
target NVE), it is important that the MAC mobility procedures are
properly executed and the corresponding MAC-VRF and IP-VRF tables on
all participating NVEs are updated. [RFC7432] describes the MAC
mobility procedures for L2-only services for both single-homed TS and
multi-homed TS. This section describes the incremental procedures
and BGP Extended Communities needed to handle the MAC mobility for
IRB. In order to place the emphasis on the differences between
L2-only and IRB use cases, the incremental procedure is described for
single-homed TS with the expectation that the additional steps needed
for multi-homed TS, can be extended per section 15 of [RFC7432].
This section describes mobility procedures for both symmetric and
asymmetric IRB. Although the language used in this section is for
IPv4 ARP, it equally applies to IPv6 ND.
When a TS moves from a source NVE to a target NVE, it can behave in
one of the following three ways:
1. TS initiates an ARP request upon a move to the target NVE
2. TS sends data packet without first initiating an ARP request to
the target NVE
3. TS is a silent host and neither initiates an ARP request nor
sends any packets
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Depending on the expexted TS's behavior, an NVE needs to handle at
least the first bullet and should be able to handle the 2nd and the
3rd bullet. The following subsections describe the procedures for
each of them where it is assumed that the MAC and IP addresses of a
TS have one-to-one relationship (i.e., there is one IP address per
MAC address and vice versa). The procedures for host mobility
detection in the presence of many-to-one relationship is outside the
scope of this document and it is covered in
[I-D.ietf-bess-evpn-irb-extended-mobility]. The many-to-one
relationship means many host IP addresses corresponding to a single
host MAC address or many host MAC addresses corresponding to a single
IP address. It should be noted that in case of IPv6, a Link Local IP
address does not count in many-to-one relationship because that
address is confined to single Ethernet Segment and it is not used for
host moblity (i.e., by definition host mobility is between two
different Ethernet Segments). Therefore, when an IPv6 host is
configured with both a Global Unicast address (or a Unique Local
address) and a Link Local address, for the purpose of host mobility,
it is considered with a single IP address.
7.1. Initiating a gratutious ARP upon a Move
In this scenario when a TS moves from a source NVE to a target NVE,
the TS initiates a gratuitous ARP upon the move to the target NVE.
The target NVE upon receiving this ARP message, updates its MAC-VRF,
IP-VRF, and ARP table with the host MAC, IP, and local adjacency
information (e.g., local interface).
Since this NVE has previously learned the same MAC and IP addresses
from the source NVE, it recognizes that there has been a MAC move and
it initiates MAC mobility procedures per [RFC7432] by advertising an
EVPN MAC/IP Advertisement route with both the MAC and IP addresses
filled in (per sections 5.1 and 6.1) along with MAC Mobility Extended
Community with the sequence number incremented by one. The target
NVE also exercises the MAC duplication detection procedure in section
15.1 of [RFC7432].
The source NVE upon receiving this MAC/IP Advertisement route,
realizes that the MAC has moved to the target NVE. It updates its
MAC-VRF and IP-VRF table accordingly with the adjacency information
of the target NVE. In the case of the asymmetric IRB, the source NVE
also updates its ARP table with the received adjacency information
and in the case of the symmetric IRB, the source NVE removes the
entry associated with the received (MAC, IP) from its local ARP
table. It then withdraws its EVPN MAC/IP Advertisement route.
Furthermore, it sends an ARP probe locally to ensure that the MAC is
gone. If an ARP response is received, the source NVE updates its ARP
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entry for that (IP, MAC) and re-advertises an EVPN MAC/IP
Advertisement route for that (IP, MAC) along with MAC Mobility
Extended Community with the sequence number incremented by one. The
source NVE also exercises the MAC duplication detection procedure in
section 15.1 of [RFC7432].
All other remote NVE devices upon receiving the MAC/IP Advertisement
route with MAC Mobility extended community compare the sequence
number in this advertisement with the one previously received. If
the new sequence number is greater than the old one, then they update
the MAC/IP addresses of the TS in their corresponding MAC-VRF and IP-
VRF tables to point to the target NVE. Furthermore, upon receiving
the MAC/IP withdraw for the TS from the source NVE, these remote PEs
perform the cleanups for their BGP tables.
7.2. Sending Data Traffic without an ARP Request
In this scenario when a TS moves from a source NVE to a target NVE,
the TS starts sending data traffic without first initiating an ARP
request.
The target NVE upon receiving the first data packet, learns the MAC
address of the TS in the data plane and updates its MAC-VRF table
with the MAC address and the local adjacency information (e.g., local
interface) accordingly. The target NVE realizes that there has been
a MAC move because the same MAC address has been learned remotely
from the source NVE.
If EVPN-IRB NVEs are configured to advertise MAC-only routes in
addition to MAC-and-IP EVPN routes, then the following steps are
taken:
o The target NVE upon learning this MAC address in the data plane,
updates this MAC address entry in the corresponding MAC-VRF with
the local adjacency information (e.g., local interface). It also
recognizes that this MAC has moved and initiates MAC mobility
procedures per [RFC7432] by advertising an EVPN MAC/IP
Advertisement route with only the MAC address filled in along with
MAC Mobility Extended Community with the sequence number
incremented by one.
o The source NVE upon receiving this MAC/IP Advertisement route,
realizes that the MAC has moved to the new NVE. It updates its
MAC-VRF table with the adjacency information for that MAC address
to point to the target NVE and withdraws its EVPN MAC/IP
Advertisement route that has only the MAC address (if it has
advertised such route previously). Furthermore, it searches for
the corresponding MAC-IP entry and sends an ARP probe for this
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(MAC,IP) pair. The ARP request message is sent both locally to
all attached TSes in that subnet as well as it is sent to other
NVEs participating in that subnet including the target NVE. Note
that the PE needs to maintain a correlation between MAC and MAC-IP
route entries in the MAC-VRF to accomplish this.
o The target NVE passes the ARP request to its locally attached TSes
and when it receives the ARP response, it updates its IP-VRF and
ARP table with the host (MAC, IP) information. It also sends an
EVPN MAC/IP Advertisement route with both the MAC and IP addresses
filled in along with MAC Mobility Extended Community with the
sequence number set to the same value as the one for MAC-only
advertisement route it sent previously.
o When the source NVE receives the EVPN MAC/IP Advertisement route,
it updates its IP-VRF table with the new adjacency information
(pointing to the target NVE). In the case of the asymmetric IRB,
the source NVE also updates its ARP table with the received
adjacency information and in the case of the symmetric IRB, the
source NVE removes the entry associated with the received (MAC,
IP) from its local ARP table. Furthermore, it withdraws its
previously advertised EVPN MAC/IP route with both the MAC and IP
address fields filled in.
o All other remote NVE devices upon receiving the MAC/IP
advertisement route with MAC Mobility extended community compare
the sequence number in this advertisement with the one previously
received. If the new sequence number is greater than the old one,
then they update the MAC/IP addresses of the TS in their
corresponding MAC-VRF, IP-VRF, and ARP tables (in the case of
asymmetric IRB) to point to the new NVE. Furthermore, upon
receiving the MAC/IP withdraw for the TS from the old NVE, these
remote PEs perform the cleanups for their BGP tables.
If EVPN-IRB NVEs are configured not to advertise MAC-only routes,
then upon receiving the first data packet, it learns the MAC address
of the TS and updates the MAC entry in the corresponding MAC-VRF
table with the local adjacency information (e.g., local interface).
It also realizes that there has been a MAC move because the same MAC
address has been learned remotely from the source NVE. It uses the
local MAC route to find the corresponding local MAC-IP route, and
sends a unicast ARP request to the host and when receiving an ARP
response, it follows the procedure outlined in section 7.1. In the
prior case, where MAC-only routes are also advertised, this procedure
of triggering a unicast ARP probe at the target PE MAY also be used
in addition to the source PE broadcast ARP probing procedure
described earlier for better convergence.
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7.3. Silent Host
In this scenario when a TS moves from a source NVE to a target NVE,
the TS is silent and it neither initiates an ARP request nor it sends
any data traffic. Therefore, neither the target nor the source NVEs
are aware of the MAC move.
On the source NVE, an age-out timer (for the silent host that has
moved) is used to trigger an ARP probe. This age-out timer can be
either ARP timer or MAC age-out timer and this is an implementation
choice. The ARP request gets sent both locally to all the attached
TSes on that subnet as well as it gets sent to all the remote NVEs
(including the target NVE) participating in that subnet. The source
NVE also withdraw the EVPN MAC/IP Advertisement route with only the
MAC address (if it has previously advertised such a route).
The target NVE passes the ARP request to its locally attached TSes
and when it receives the ARP response, it updates its MAC-VRF, IP-
VRF, and ARP table with the host (MAC, IP) and local adjacency
information (e.g., local interface). It also sends an EVPN MAC/IP
advertisement route with both the MAC and IP address fields filled in
along with MAC Mobility Extended Community with the sequence number
incremented by one.
When the source NVE receives the EVPN MAC/IP Advertisement route, it
updates its IP-VRF table with the new adjacency information (pointing
to the target NVE). In the case of the asymmetric IRB, the source
NVE also updates its ARP table with the received adjacency
information and in the case of the symmetric IRB, the source NVE
removes the entry associated with the received (MAC, IP) from its
local ARP table. Furthermore, it withdraws its previously advertised
EVPN MAC/IP route with both the MAC and IP address fields filled in.
All other remote NVE devices upon receiving the MAC/IP Advertisement
route with MAC Mobility extended community compare the sequence
number in this advertisement with the one previously received. If
the new sequence number is greater than the old one, then they update
the MAC/IP addresses of the TS in their corresponding MAC-VRF, IP-
VRF, and ARP (in the case of asymmetric IRB) tables to point to the
new NVE. Furthermore, upon receiving the MAC/IP withdraw for the TS
from the old NVE, these remote PEs perform the cleanups for their BGP
tables.
8. BGP Encoding
This document defines one new BGP Extended Community for EVPN.
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8.1. Router's MAC Extended Community
A new EVPN BGP Extended Community called Router's MAC is introduced
here. This new extended community is a transitive extended community
with the Type field of 0x06 (EVPN) and the Sub-Type of 0x03. It may
be advertised along with Encapsulation Extended Community defined in
section 4.1 of [I-D.ietf-idr-tunnel-encaps].
The Router's MAC Extended Community is encoded as an 8-octet value as
follows:
0 1 2 3
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=0x03 | Router's MAC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router's MAC Cont'd |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Router's MAC Extended Community
This extended community is used to carry the PE's MAC address for
symmetric IRB scenarios and it is sent with EVPN RT-2. The
advertising PE SHALL only attach a single Router's MAC Extended
Community to a route. In case the receiving PE receives more than
one Router's MAC Extended Community with a route, it SHALL process
the first one in the list and not store and propagate the others.
9. Operational Models for Symmetric Inter-Subnet Forwarding
The following sections describe two main symmetric IRB forwarding
scenarios (within a DC -- i.e., intra-DC) along with the
corresponding procedures. In the following scenarios, without loss
of generality, it is assumed that a given tenant is represented by a
single IP-VPN instance. Therefore, on a given PE, a tenant is
represented by a single IP-VRF table and one or more MAC-VRF tables.
9.1. IRB forwarding on NVEs for Tenant Systems
This section covers the symmetric IRB procedures for the scenario
where each Tenant System (TS) is attached to one or more NVEs and its
host IP and MAC addresses are learned by the attached NVEs and are
distributed to all other NVEs that are interested in participating in
both intra-subnet and inter-subnet communications with that TS.
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In this scenario, without loss of generality, it is assumed that NVEs
operate in VLAN-based service interface mode with one bridge table(s)
per MAC-VRF. Thus, for a given tenant, an NVE has one MAC-VRF for
each tenant subnet (e.g., each VLAN) that is configured for extension
via VxLAN or NVGRE encapsulation. In the case of VLAN-aware
bundling, then each MAC-VRF consists of multiple Bridge Tables (e.g.,
one bridge table per VLAN). The MAC-VRFs on an NVE for a given
tenant are associated with an IP-VRF corresponding to that tenant (or
IP-VPN instance) via their IRB interfaces.
Since VxLAN and NVGRE encapsulations require inner Ethernet header
(inner MAC SA/DA), and since for inter-subnet traffic, TS MAC address
cannot be used, the ingress NVE's MAC address is used as inner MAC
SA. The NVE's MAC address is the device MAC address and it is common
across all MAC-VRFs and IP-VRFs. This MAC address is advertised
using the new EVPN Router's MAC Extended Community (section 8.1).
Figure 6 below illustrates this scenario where a given tenant (e.g.,
an IP-VPN instance) has three subnets represented by MAC-VRF1, MAC-
VRF2, and MAC-VRF3 across two NVEs. There are five TSes that are
associated with these three MAC-VRFs -- i.e., TS1, TS4, and TS5 are
on the same subnet (e.g., same MAC-VRF/VLAN). TS1 and TS5 are
associated with MAC-VRF1 on NVE1, while TS4 is associated with MAC-
VRF1 on NVE2. TS2 is associated with MAC-VRF2 on NVE1, and TS3 is
associated with MAC-VRF3 on NVE2. MAC-VRF1 and MAC-VRF2 on NVE1 are
in turn associated with IP-VRF1 on NVE1 and MAC-VRF1 and MAC-VRF3 on
NVE2 are associated with IP-VRF1 on NVE2. When TS1, TS5, and TS4
exchange traffic with each other, only the L2 forwarding (bridging)
part of the IRB solution is exercised because all these TSes belong
to the same subnet. However, when TS1 wants to exchange traffic with
TS2 or TS3 which belong to different subnets, both bridging and
routing parts of the IRB solution are exercised. The following
subsections describe the control and data planes operations for this
IRB scenario in details.
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NVE1 +---------+
+-------------+ | |
TS1-----| MACx| | | NVE2
(IP1/M1) |(MAC- | | | +-------------+
TS5-----| VRF1)\ | | MPLS/ | |MACy (MAC- |-----TS3
(IP5/M5) | \ | | VxLAN/ | | / VRF3) | (IP3/M3)
| (IP-VRF1)|----| NVGRE |---|(IP-VRF1) |
| / | | | | \ |
TS2-----|(MAC- / | | | | (MAC- |-----TS4
(IP2/M2) | VRF2) | | | | VRF1) | (IP4/M4)
+-------------+ | | +-------------+
| |
+---------+
Figure 6: IRB forwarding on NVEs for Tenant Systems
9.1.1. Control Plane Operation
Each NVE advertises a MAC/IP Advertisement route (i.e., Route Type 2)
for each of its TSes with the following field set:
o RD and ESI per [RFC7432]
o Ethernet Tag = 0; assuming VLAN-based service
o MAC Address Length = 48
o MAC Address = Mi ; where i = 1,2,3,4, or 5 in the above example
o IP Address Length = 32 or 128
o IP Address = IPi ; where i = 1,2,3,4, or 5 in the above example
o Label1 = MPLS Label or VNI corresponding to MAC-VRF
o Label2 = MPLS Label or VNI corresponding to IP-VRF
Each NVE advertises an EVPN RT-2 route with two Route Targets (one
corresponding to its MAC-VRF and the other corresponding to its IP-
VRF. Furthermore, the EVPN RT-2 is advertised with two BGP Extended
Communities. The first BGP Extended Community identifies the tunnel
type and it is called Encapsulation Extended Community as defined in
[I-D.ietf-idr-tunnel-encaps] and the second BGP Extended Community
includes the MAC address of the NVE (e.g., MACx for NVE1 or MACy for
NVE2) as defined in section 8.1. The Router's MAC Extended community
MUST be added when Ethernet NVO tunnel is used. If IP NVO tunnel
type is used, then there is no need to send this second Extended
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Community. It should be noted that IP NVO tunnel type is only
applicable to symmetric IRB procedures.
Upon receiving this advertisement, the receiving NVE performs the
following:
o It uses Route Targets corresponding to its MAC-VRF and IP-VRF for
identifying these tables and subsequently importing the MAC and IP
addresses into them respectively.
o It imports the MAC address from MAC/IP Advertisement route into
the MAC-VRF with BGP Next Hop address as the underlay tunnel
destination address (e.g., VTEP DA for VxLAN encapsulation) and
Label1 as VNI for VxLAN encapsulation or EVPN label for MPLS
encapsulation.
o If the route carries the new Router's MAC Extended Community, and
if the receiving NVE uses Ethernet NVO tunnel, then the receiving
NVE imports the IP address into IP-VRF with NVE's MAC address
(from the new Router's MAC Extended Community) as inner MAC DA and
BGP Next Hop address as the underlay tunnel destination address,
VTEP DA for VxLAN encapsulation and Label2 as IP-VPN VNI for VxLAN
encapsulation.
o If the receiving NVE uses MPLS encapsulation, then the receiving
NVE imports the IP address into IP-VRF with BGP Next Hop address
as the underlay tunnel destination address, and Label2 as IP-VPN
label for MPLS encapsulation.
If the receiving NVE receives an EVPN RT-2 with only Label1 and only
a single Route Target corresponding to IP-VRF, or if it receives an
EVPN RT-2 with only a single Route Target corresponding to MAC-VRF
but with both Label1 and Label2, or if it receives an EVPN RT-2 with
MAC Address Length of zero, then it MUST use the treat-as-withdraw
approach [RFC7606] and SHOULD log an error message.
9.1.2. Data Plane Operation
The following description of the data-plane operation describes just
the logical functions and the actual implementation may differ. Lets
consider data-plane operation when TS1 in subnet-1 (MAC-VRF1) on NVE1
wants to send traffic to TS3 in subnet-3 (MAC-VRF3) on NVE2.
o NVE1 receives a packet with MAC DA corresponding to the MAC-VRF1
IRB interface on NVE1 (the interface between MAC-VRF1 and IP-
VRF1), and VLAN-tag corresponding to MAC-VRF1.
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o Upon receiving the packet, the NVE1 uses VLAN-tag to identify the
MAC-VRF1. It then looks up the MAC DA and forwards the frame to
its IRB interface.
o The Ethernet header of the packet is stripped and the packet is
fed to the IP-VRF where an IP lookup is performed on the
destination IP address. NVE1 also decrements the TTL/hop limit
for that packet by one and if it reaches zero, NVE1 discards the
packet. This lookup yields the outgoing NVO tunnel and the
required encapsulation. If the encapsulation is for Ethernet NVO
tunnel, then it includes the egress NVE's MAC address as inner MAC
DA, the egress NVE's IP address (e.g., BGP Next Hop address) as
the VTEP DA, and the VPN-ID as the VNI. The inner MAC SA and VTEP
SA are set to NVE's MAC and IP addresses respectively. If it is a
MPLS encapsulation, then corresponding EVPN and LSP labels are
added to the packet. The packet is then forwarded to the egress
NVE.
o On the egress NVE, if the packet arrives on Ethernet NVO tunnel
(e.g., it is VxLAN encapsulated), then the NVO tunnel header is
removed. Since the inner MAC DA is the egress NVE's MAC address,
the egress NVE knows that it needs to perform an IP lookup. It
uses the VNI to identify the IP-VRF table. If the packet is MPLS
encapsulated, then the EVPN label lookup identifies the IP-VRF
table. Next, an IP lookup is performed for the destination TS
(TS3) which results in an access-facing IRB interface over which
the packet is sent. Before sending the packet over this
interface, the ARP table is consulted to get the destination TS's
MAC address. NVE2 also decrements the TTL/hop limit for that
packet by one and if it reaches zero, NVE2 discards the packet.
o The IP packet is encapsulated with an Ethernet header with MAC SA
set to that of IRB interface MAC address (i.e, IRB interface
between MAC-VRF3 and IP-VRF1 on NVE2) and MAC DA set to that of
destination TS (TS3) MAC address. The packet is sent to the
corresponding MAC-VRF (i.e., MAC-VRF3) and after a lookup of MAC
DA, is forwarded to the destination TS (TS3) over the
corresponding interface.
In this symmetric IRB scenario, inter-subnet traffic between NVEs
will always use the IP-VRF VNI/MPLS label. For instance, traffic
from TS2 to TS4 will be encapsulated by NVE1 using NVE2's IP-VRF VNI/
MPLS label, as long as TS4's host IP is present in NVE1's IP-VRF.
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9.2. IRB forwarding on NVEs for Subnets behind Tenant Systems
This section covers the symmetric IRB procedures for the scenario
where some Tenant Systems (TSes) support one or more subnets and
these TSes are associated with one or more NVEs. Therefore, besides
the advertisement of MAC/IP addresses for each TS which can be multi-
homed with All-Active redundancy mode, the associated NVE needs to
also advertise the subnets statically configured on each TS.
The main difference between this solution and the previous one is the
additional advertisement corresponding to each subnet. These subnet
advertisements are accomplished using the EVPN IP Prefix route
defined in [I-D.ietf-bess-evpn-prefix-advertisement]. These subnet
prefixes are advertised with the IP address of their associated TS
(which is in overlay address space) as their next hop. The receiving
NVEs perform recursive route resolution to resolve the subnet prefix
with its advertising NVE so that they know which NVE to forward the
packets to when they are destined for that subnet prefix.
The advantage of this recursive route resolution is that when a TS
moves from one NVE to another, there is no need to re-advertise any
of the subnet prefixes for that TS. All it is needed is to advertise
the IP/MAC addresses associated with the TS itself and exercise MAC
mobility procedures for that TS. The recursive route resolution
automatically takes care of the updates for the subnet prefixes of
that TS.
Figure 7 illustrates this scenario where a given tenant (e.g., an IP-
VPN service) has three subnets represented by MAC-VRF1, MAC-VRF2, and
MAC-VRF3 across two NVEs. There are four TSes associated with these
three MAC-VRFs -- i.e., TS1 is connected to MAC-VRF1 on NVE1, TS2 is
connected to MAC-VRF2 on NVE1, TS3 is connected to MAC- VRF3 on NVE2,
and TS4 is connected to MAC-VRF1 on NVE2. TS1 has two subnet
prefixes (SN1 and SN2) and TS3 has a single subnet prefix, SN3. The
MAC-VRFs on each NVE are associated with their corresponding IP-VRF
using their IRB interfaces. When TS4 and TS1 exchange intra- subnet
traffic, only L2 forwarding (bridging) part of the IRB solution is
used (i.e., the traffic only goes through their MAC- VRFs); however,
when TS3 wants to forward traffic to SN1 or SN2 sitting behind TS1
(inter-subnet traffic), then both bridging and routing parts of the
IRB solution are exercised (i.e., the traffic goes through the
corresponding MAC-VRFs and IP-VRFs). If TS4, for example, wants to
reach SN1, it uses its default route and sends the packet to the MAC
address associated with the IRB interface on NVE2, NVE2 then makes an
IP lookup in its IP- VRF, and finds an entry for SN1. The following
subsections describe the control and data planes operations for this
IRB scenario in details.
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NVE1 +----------+
SN1--+ +-------------+ | |
|--TS1-----|(MAC- \ | | |
SN2--+ IP1/M1 | VRF1) \ | | |
| (IP-VRF)|---| |
| / | | |
TS2-----|(MAC- / | | MPLS/ |
IP2/M2 | VRF2) | | VxLAN/ |
+-------------+ | NVGRE |
+-------------+ | |
SN3--+--TS3-----|(MAC-\ | | |
IP3/M3 | VRF3)\ | | |
| (IP-VRF)|---| |
| / | | |
TS4-----|(MAC- / | | |
IP4/M4 | VRF1) | | |
+-------------+ +----------+
NVE2
Figure 7: IRB forwarding on NVEs for subnets behind TSes
Note that in figure 7, above, SN1 and SN2 are configured on NVE1,
which then advertises each in an IP Prefix route. Similarly, SN3 is
configured on NVE2, which then advertises it in an IP Prefix route.
9.2.1. Control Plane Operation
Each NVE advertises a Route Type-5 (EVPN RT-5, IP Prefix route
defined in [I-D.ietf-bess-evpn-prefix-advertisement]) for each of its
subnet prefixes with the IP address of its TS as the next hop
(gateway address field) as follows:
o RD associated with the IP-VRF
o ESI = 0
o Ethernet Tag = 0;
o IP Prefix Length = 0 to 32 or 0 to 128
o IP Prefix = SNi
o Gateway Address = IPi; IP address of TS
o MPLS Label = 0
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This EVPN RT-5 is advertised with one or more Route Targets
associated with the IP-VRF from which the route is originated.
Each NVE also advertises an EVPN RT-2 (MAC/IP Advertisement Route)
along with their associated Route Targets and Extended Communities
for each of its TSes exactly as described in section 9.1.1.
Upon receiving the EVPN RT-5 advertisement, the receiving NVE
performs the following:
o It uses the Route Target to identify the corresponding IP-VRF
o It imports the IP prefix into its corresponding IP-VRF that is
configured with an import RT that is one of the RTs being carried
by the EVPN RT-5 route along with the IP address of the associated
TS as its next hop.
When receiving the EVPN RT-2 advertisement, the receiving NVE imports
MAC/IP addresses of the TS into the corresponding MAC-VRF and IP-VRF
per section 9.1.1. When both routes exist, recursive route
resolution is performed to resolve the IP prefix (received in EVPN
RT-5) to its corresponding NVE's IP address (e.g., its BGP next hop).
BGP next hop will be used as the underlay tunnel destination address
(e.g., VTEP DA for VxLAN encapsulation) and Router's MAC will be used
as inner MAC for VxLAN encapsulation.
9.2.2. Data Plane Operation
The following description of the data-plane operation describes just
the logical functions and the actual implementation may differ. Lets
consider data-plane operation when a host on SN1 sitting behind TS1
wants to send traffic to a host sitting behind SN3 behind TS3.
o TS1 send a packet with MAC DA corresponding to the MAC-VRF1 IRB
interface of NVE1, and VLAN-tag corresponding to MAC-VRF1.
o Upon receiving the packet, the ingress NVE1 uses VLAN-tag to
identify the MAC-VRF1. It then looks up the MAC DA and forwards
the frame to its IRB interface just like section 9.1.1.
o The Ethernet header of the packet is stripped and the packet is
fed to the IP-VRF; where, IP lookup is performed on the
destination address. This lookup yields the fields needed for
VxLAN encapsulation with NVE2's MAC address as the inner MAC DA,
NVE'2 IP address as the VTEP DA, and the VNI. MAC SA is set to
NVE1's MAC address and VTEP SA is set to NVE1's IP address. NVE1
also decrements the TTL/hop limit for that packet by one and if it
reaches zero, NVE1 discards the packet.
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o The packet is then encapsulated with the proper header based on
the above info and is forwarded to the egress NVE (NVE2).
o On the egress NVE (NVE2), assuming the packet is VxLAN
encapsulated, the VxLAN and the inner Ethernet headers are removed
and the resultant IP packet is fed to the IP-VRF associated with
that the VNI.
o Next, a lookup is performed based on IP DA (which is in SN3) in
the associated IP-VRF of NVE2. The IP lookup yields the access-
facing IRB interface over which the packet needs to be sent.
Before sending the packet over this interface, the ARP table is
consulted to get the destination TS (TS3) MAC address. NVE2 also
decrements the TTL/hop limit for that packet by one and if it
reaches zero, NVE2 discards the packet.
o The IP packet is encapsulated with an Ethernet header with the MAC
SA set to that of the access-facing IRB interface of the egress
NVE (NVE2) and the MAC DA is set to that of destination TS (TS3)
MAC address. The packet is sent to the corresponding MAC-VRF3 and
after a lookup of MAC DA, is forwarded to the destination TS (TS3)
over the corresponding interface.
10. Acknowledgements
The authors would like to thank Sami Boutros, Jeffrey Zhang,
Krzysztof Szarkowicz, Lukas Krattiger and Neeraj Malhotra for their
valuable comments. The authors would also like to thank Linda
Dunbar, Florin Balus, Yakov Rekhter, Wim Henderickx, Lucy Yong, and
Dennis Cai for their feedback and contributions.
11. Security Considerations
The security considerations for layer-2 forwarding in this document
follow that of [RFC7432] for MPLS encapsulation and it follows that
of [RFC8365] for VxLAN or NVGRE encapsulations. This section
describes additional considerations.
This document describes a set of procedures for Inter-Subnet
Forwarding of tenant traffic across PEs (or NVEs). These procedures
include both layer-2 forwarding and layer-3 routing on a packet by
packet basis. The security consideration for layer-3 routing in this
document follows that of [RFC4365] with the exception for the
application of routing protocols between CEs and PEs. Contrary to
[RFC4364], this document does not describe route distribution
techniques between CEs and PEs, but rather considers the CEs as TSes
or VAs that do not run dynamic routing protocols. This can be
considered a security advantage, since dynamic routing protocols can
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be blocked on the NVE/PE ACs, not allowing the tenant to interact
with the infrastructure's dynamic routing protocols.
The VPN scheme described in this document does not provide the
quartet of security properties mentioned in [RFC4365]
(confidentiality protection, source authentication, integrity
protection, replay protection). If these are desired, they must be
provided by mechanisms that are outside the scope of the VPN
mechanisms.
In this document, the EVPN RT-5 is used for certain scenarios. This
route uses an Overlay Index that requires a recursive resolution to a
different EVPN route (an EVPN RT-2). Because of this, it is worth
noting that any action that ends up filtering or modifying the EVPN
RT-2 route used to convey the Overlay Indexes, will modify the
resolution of the EVPN RT-5 and therefore the forwarding of packets
to the remote subnet.
12. IANA Considerations
IANA has allocated a new transitive extended community Type of 0x06
and Sub-Type of 0x03 for EVPN Router's MAC Extended Community.
This document has been listed as an additional reference for the MAC/
IP Advertisement route in the EVPN Route Type registry.
13. References
13.1. Normative References
[I-D.ietf-bess-evpn-prefix-advertisement]
Rabadan, J., Henderickx, W., Drake, J., Lin, W., and A.
Sajassi, "IP Prefix Advertisement in EVPN", draft-ietf-
bess-evpn-prefix-advertisement-11 (work in progress), May
2018.
[I-D.ietf-idr-tunnel-encaps]
Patel, K., Velde, G., Sangli, S., and J. Scudder, "The BGP
Tunnel Encapsulation Attribute", draft-ietf-idr-tunnel-
encaps-22 (work in progress), January 2021.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
[RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
<https://www.rfc-editor.org/info/rfc7348>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
Patel, "Revised Error Handling for BGP UPDATE Messages",
RFC 7606, DOI 10.17487/RFC7606, August 2015,
<https://www.rfc-editor.org/info/rfc7606>.
[RFC7637] Garg, P., Ed. and Y. Wang, Ed., "NVGRE: Network
Virtualization Using Generic Routing Encapsulation",
RFC 7637, DOI 10.17487/RFC7637, September 2015,
<https://www.rfc-editor.org/info/rfc7637>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8365] Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R.,
Uttaro, J., and W. Henderickx, "A Network Virtualization
Overlay Solution Using Ethernet VPN (EVPN)", RFC 8365,
DOI 10.17487/RFC8365, March 2018,
<https://www.rfc-editor.org/info/rfc8365>.
13.2. Informative References
[I-D.ietf-bess-evpn-irb-extended-mobility]
Malhotra, N., Sajassi, A., Pattekar, A., Lingala, A.,
Rabadan, J., and J. Drake, "Extended Mobility Procedures
for EVPN-IRB", draft-ietf-bess-evpn-irb-extended-
mobility-03 (work in progress), May 2020.
[I-D.ietf-nvo3-vxlan-gpe]
Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol
Extension for VXLAN (VXLAN-GPE)", draft-ietf-nvo3-vxlan-
gpe-10 (work in progress), July 2020.
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[RFC4365] Rosen, E., "Applicability Statement for BGP/MPLS IP
Virtual Private Networks (VPNs)", RFC 4365,
DOI 10.17487/RFC4365, February 2006,
<https://www.rfc-editor.org/info/rfc4365>.
[RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP)
Version 3 for IPv4 and IPv6", RFC 5798,
DOI 10.17487/RFC5798, March 2010,
<https://www.rfc-editor.org/info/rfc5798>.
[RFC7365] Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
Rekhter, "Framework for Data Center (DC) Network
Virtualization", RFC 7365, DOI 10.17487/RFC7365, October
2014, <https://www.rfc-editor.org/info/rfc7365>.
Authors' Addresses
Ali Sajassi
Cisco Systems
Email: sajassi@cisco.com
Samer Salam
Cisco Systems
Email: ssalam@cisco.com
Samir Thoria
Cisco Systems
Email: sthoria@cisco.com
John E Drake
Juniper
Email: jdrake@juniper.net
Jorge Rabadan
Nokia
Email: jorge.rabadan@nokia.com
Sajassi, et al. Expires January 27, 2022 [Page 36]
