Internet DRAFT - draft-ietf-bess-dci-evpn-overlay
draft-ietf-bess-dci-evpn-overlay
BESS Workgroup J. Rabadan (Ed.)
Internet Draft S. Sathappan
Intended status: Standards Track W. Henderickx
Nokia
A. Sajassi
Cisco
J. Drake
Juniper
Expires: September 3, 2018 March 2, 2018
Interconnect Solution for EVPN Overlay networks
draft-ietf-bess-dci-evpn-overlay-10
Abstract
This document describes how Network Virtualization Overlays (NVO) can
be connected to a Wide Area Network (WAN) in order to extend the
layer-2 connectivity required for some tenants. The solution analyzes
the interaction between NVO networks running Ethernet Virtual Private
Networks (EVPN) and other L2VPN technologies used in the WAN, such as
Virtual Private LAN Services (VPLS), VPLS extensions for Provider
Backbone Bridging (PBB-VPLS), EVPN or PBB-EVPN. It also describes how
the existing technical specifications apply to the Interconnection
and extends the EVPN procedures needed in some cases. In particular,
this document describes how EVPN routes are processed on Gateways
(GWs) that interconnect EVPN-Overlay and EVPN-MPLS networks, as well
as the Interconnect Ethernet Segment (I-ES) to provide multi-homing,
and the use of the Unknown MAC route to avoid MAC scale issues on
Data Center Network Virtualization Edge (NVE) devices.
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), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
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Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
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Table of Contents
1. Conventions and Terminology . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Decoupled Interconnect solution for EVPN overlay networks . . . 6
3.1. Interconnect requirements . . . . . . . . . . . . . . . . . 7
3.2. VLAN-based hand-off . . . . . . . . . . . . . . . . . . . . 8
3.3. PW-based (Pseudowire-based) hand-off . . . . . . . . . . . 8
3.4. Multi-homing solution on the GWs . . . . . . . . . . . . . 9
3.5. Gateway Optimizations . . . . . . . . . . . . . . . . . . . 9
3.5.1. MAC Address Advertisement Control . . . . . . . . . . . 9
3.5.2. ARP/ND flooding control . . . . . . . . . . . . . . . . 10
3.5.3. Handling failures between GW and WAN Edge routers . . . 11
4. Integrated Interconnect solution for EVPN overlay networks . . 11
4.1. Interconnect requirements . . . . . . . . . . . . . . . . . 12
4.2. VPLS Interconnect for EVPN-Overlay networks . . . . . . . . 13
4.2.1. Control/Data Plane setup procedures on the GWs . . . . 13
4.2.2. Multi-homing procedures on the GWs . . . . . . . . . . 14
4.3. PBB-VPLS Interconnect for EVPN-Overlay networks . . . . . . 14
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4.3.1. Control/Data Plane setup procedures on the GWs . . . . 14
4.3.2. Multi-homing procedures on the GWs . . . . . . . . . . 15
4.4. EVPN-MPLS Interconnect for EVPN-Overlay networks . . . . . 15
4.4.1. Control Plane setup procedures on the GWs . . . . . . . 15
4.4.2. Data Plane setup procedures on the GWs . . . . . . . . 17
4.4.3. Multi-homing procedure extensions on the GWs . . . . . 18
4.4.4. Impact on MAC Mobility procedures . . . . . . . . . . . 20
4.4.5. Gateway optimizations . . . . . . . . . . . . . . . . . 20
4.4.6. Benefits of the EVPN-MPLS Interconnect solution . . . . 21
4.5. PBB-EVPN Interconnect for EVPN-Overlay networks . . . . . . 22
4.5.1. Control/Data Plane setup procedures on the GWs . . . . 22
4.5.2. Multi-homing procedures on the GWs . . . . . . . . . . 22
4.5.3. Impact on MAC Mobility procedures . . . . . . . . . . . 23
4.5.4. Gateway optimizations . . . . . . . . . . . . . . . . . 23
4.6. EVPN-VXLAN Interconnect for EVPN-Overlay networks . . . . . 23
4.6.1. Globally unique VNIs in the Interconnect network . . . 24
4.6.2. Downstream assigned VNIs in the Interconnect network . 24
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 25
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 26
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.1. Normative References . . . . . . . . . . . . . . . . . . . 26
7.2. Informative References . . . . . . . . . . . . . . . . . . 27
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 28
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 28
10. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 29
1. Conventions and Terminology
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
AC: Attachment Circuit.
ARP: Address Resolution Protocol.
BUM: refers to Broadcast, Unknown unicast and Multicast traffic.
CE: Customer Equipment.
CFM: Connectivity Fault Management.
DC and DCI: Data Center and Data Center Interconnect.
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DC RR(s) and WAN RR(s): refers to the Data Center and Wide Area
Network Route Reflectors, respectively.
DF and NDF: Designated Forwarder and Non-Designated Forwarder.
EVPN: Ethernet Virtual Private Network, as in [RFC7432].
EVI: EVPN Instance.
EVPN Tunnel binding: refers to a tunnel to a remote PE/NVE for a
given EVI. Ethernet packets in these bindings are encapsulated with
the Overlay or MPLS encapsulation and the EVPN label at the bottom of
the stack.
ES and vES: Ethernet Segment and virtual Ethernet Segment.
ESI: Ethernet Segment Identifier.
GW: Gateway or Data Center Gateway.
I-ES and I-ESI: Interconnect Ethernet Segment and Interconnect
Ethernet Segment Identifier. An I-ES is defined on the GWs for multi-
homing to/from the WAN.
MAC-VRF: refers to an EVI instance in a particular node.
MP2P and LSM tunnels: refer to Multi-Point to Point and Label
Switched Multicast tunnels.
ND: Neighbor Discovery protocol.
NVE: Network Virtualization Edge.
NVGRE: Network Virtualization using Generic Routing Encapsulation.
NVO: refers to Network Virtualization Overlays.
OAM: Operations and Maintenance.
PBB: Provider Backbone Bridging.
PE: Provider Edge.
PW: Pseudowire.
RD: Route-Distinguisher.
RT: Route-Target.
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S/C-TAG: refers to a combination of Service Tag and Customer Tag in a
802.1Q frame.
TOR: Top-Of-Rack switch.
UMR: Unknown MAC Route.
VNI/VSID: refers to VXLAN/NVGRE virtual identifiers.
VPLS: Virtual Private LAN Service.
VSI: Virtual Switch Instance or VPLS instance in a particular PE.
VXLAN: Virtual eXtensible LAN.
2. Introduction
[EVPN-Overlays] discusses the use of Ethernet Virtual Private
Networks (EVPN) [RFC7432] as the control plane for Network
Virtualization Overlays (NVO), where VXLAN [RFC7348], NVGRE [RFC7637]
or MPLS over GRE [RFC4023] can be used as possible data plane
encapsulation options.
While this model provides a scalable and efficient multi-tenant
solution within the Data Center, it might not be easily extended to
the Wide Area Network (WAN) in some cases due to the requirements and
existing deployed technologies. For instance, a Service Provider
might have an already deployed Virtual Private LAN Service (VPLS)
[RFC4761][RFC4762], VPLS extensions for Provider Backbone Bridging
(PBB-VPLS) [RFC7041], EVPN [RFC7432] or PBB-EVPN [RFC7623] network
that has to be used to interconnect Data Centers and WAN VPN users. A
Gateway (GW) function is required in these cases. In fact, [EVPN-
Overlays] discusses two main Data Center Interconnect solution
groups: "DCI using GWs" and "DCI using ASBRs". This document
specifies the solutions that correspond to the "DCI using GWs" group.
It is assumed that the NVO Gateway (GW) and the WAN Edge functions
can be decoupled in two separate systems or integrated into the same
system. The former option will be referred as "Decoupled Interconnect
solution" throughout the document, whereas the latter one will be
referred as "Integrated Interconnect solution".
The specified procedures are local to the redundant GWs connecting a
DC to the WAN. The document does not preclude any combination across
different DCs for the same tenant. For instance, a "Decoupled"
solution can be used in GW1 and GW2 (for DC1) and an "Integrated"
solution can be used in GW3 and GW4 (for DC2).
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While the Gateways and WAN PEs use existing specifications in some
cases, the document also defines extensions that are specific to DCI.
In particular, those extensions are:
o The Interconnect Ethernet Segment (I-ES), an Ethernet Segment that
can be associated to a set of PWs or other tunnels. I-ES defined in
this document is not associated with a set of Ethernet links, as
per [RFC7432], but rather with a set of virtual tunnels (e.g., a
set of PWs). This set of virtual tunnels is referred to as vES
[VIRTUAL-ES].
o The use of the Unknown MAC route in a DCI scenario.
o The processing of EVPN routes on Gateways with MAC-VRFs connecting
EVPN-Overlay and EVPN-MPLS networks, or EVPN-Overlay and EVPN-
Overlay networks.
3. Decoupled Interconnect solution for EVPN overlay networks
This section describes the interconnect solution when the GW and WAN
Edge functions are implemented in different systems. Figure 1 depicts
the reference model described in this section. Note that, although
not shown in Figure 1, GWs may have local ACs (Attachment Circuits).
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+--+
|CE|
+--+
|
+----+
+----| PE |----+
+---------+ | +----+ | +---------+
+----+ | +---+ +----+ +----+ +---+ | +----+
|NVE1|--| | | |WAN | |WAN | | | |--|NVE3|
+----+ | |GW1|--|Edge| |Edge|--|GW3| | +----+
| +---+ +----+ +----+ +---+ |
| NVO-1 | | WAN | | NVO-2 |
| +---+ +----+ +----+ +---+ |
| | | |WAN | |WAN | | | |
+----+ | |GW2|--|Edge| |Edge|--|GW4| | +----+
|NVE2|--| +---+ +----+ +----+ +---+ |--|NVE4|
+----+ +---------+ | | +---------+ +----+
+--------------+
|<-EVPN-Overlay-->|<-VLAN->|<-WAN L2VPN->|<--PW-->|<--EVPN-Overlay->|
hand-off hand-off
Figure 1 Decoupled Interconnect model
The following section describes the interconnect requirements for
this model.
3.1. Interconnect requirements
The Decoupled Interconnect architecture is intended to be deployed in
networks where the EVPN-Overlay and WAN providers are different
entities and a clear demarcation is needed. This solution solves the
following requirements:
o A simple connectivity hand-off between the EVPN-Overlay network
provider and the WAN provider so that QoS and security enforcement
is easily accomplished.
o Independence of the Layer Two VPN (L2VPN) technology deployed in
the WAN.
o Multi-homing between GW and WAN Edge routers, including per-service
load balancing. Per-flow load balancing is not a strong requirement
since a deterministic path per service is usually required for an
easy QoS and security enforcement.
o Support of Ethernet OAM and Connectivity Fault Management (CFM)
[802.1AG][Y.1731] functions between the GW and the WAN Edge router
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to detect individual AC failures.
o Support for the following optimizations at the GW:
+ Flooding reduction of unknown unicast traffic sourced from the DC
Network Virtualization Edge devices (NVEs).
+ Control of the WAN MAC addresses advertised to the DC.
+ Address Resolution Protocol (ARP) and Neighbor Discovery (ND)
flooding control for the requests coming from the WAN.
3.2. VLAN-based hand-off
In this option, the hand-off between the GWs and the WAN Edge routers
is based on VLANs [802.1Q-2014]. This is illustrated in Figure 1
(between the GWs in NVO-1 and the WAN Edge routers). Each MAC-VRF in
the GW is connected to a different VSI/MAC-VRF instance in the WAN
Edge router by using a different C-TAG VLAN ID or a different
combination of S/C-TAG VLAN IDs that matches at both sides.
This option provides the best possible demarcation between the DC and
WAN providers and it does not require control plane interaction
between both providers. The disadvantage of this model is the
provisioning overhead since the service has to be mapped to a C-TAG
or S/C-TAG VLAN ID combination at both GW and WAN Edge routers.
In this model, the GW acts as a regular Network Virtualization Edge
(NVE) towards the DC. Its control plane, data plane procedures and
interactions are described in [EVPN-Overlays].
The WAN Edge router acts as a (PBB-)VPLS or (PBB-)EVPN PE with
attachment circuits (ACs) to the GWs. Its functions are described in
[RFC4761], [RFC4762], [RFC6074] or [RFC7432], [RFC7623].
3.3. PW-based (Pseudowire-based) hand-off
If MPLS between the GW and the WAN Edge router is an option, a PW-
based Interconnect solution can be deployed. In this option the
hand-off between both routers is based on FEC128-based PWs [RFC4762]
or FEC129-based PWs (for a greater level of network automation)
[RFC6074]. Note that this model still provides a clear demarcation
boundary between DC and WAN (since there is a single PW between each
MAC-VRF and peer VSI), and security/QoS policies may be applied on a
per PW basis. This model provides better scalability than a C-TAG
based hand-off and less provisioning overhead than a combined C/S-TAG
hand-off. The PW-based hand-off interconnect is illustrated in Figure
1 (between the NVO-2 GWs and the WAN Edge routers).
In this model, besides the usual MPLS procedures between GW and WAN
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Edge router [RFC3031], the GW MUST support an interworking function
in each MAC-VRF that requires extension to the WAN:
o If a FEC128-based PW is used between the MAC-VRF (GW) and the VSI
(WAN Edge), the corresponding VCID MUST be provisioned on the MAC-
VRF and match the VCID used in the peer VSI at the WAN Edge router.
o If BGP Auto-discovery [RFC6074] and FEC129-based PWs are used
between the GW MAC-VRF and the WAN Edge VSI, the provisioning of
the VPLS-ID MUST be supported on the MAC-VRF and MUST match the
VPLS-ID used in the WAN Edge VSI.
If a PW-based handoff is used, the GW's AC (or point of attachment to
the EVPN Instance) uses a combination of a PW label and VLAN IDs. PWs
are treated as service interfaces defined in [RFC7432].
3.4. Multi-homing solution on the GWs
EVPN single-active multi-homing, i.e. per-service load-balancing
multi-homing is required in this type of interconnect.
The GWs will be provisioned with a unique ES per WAN interconnect,
and the hand-off attachment circuits or PWs between the GW and the
WAN Edge router will be assigned an ESI for such ES. The ESI will be
administratively configured on the GWs according to the procedures in
[RFC7432]. This Interconnect ES will be referred as "I-ES" hereafter,
and its identifier will be referred as "I-ESI". [RFC7432] describes
different ESI Types. The use of Type 0 for the I-ESI is RECOMMENDED
in this document.
The solution (on the GWs) MUST follow the single-active multi-homing
procedures as described in [EVPN-Overlays] for the provisioned I-ESI,
i.e. Ethernet A-D routes per ES and per EVI will be advertised to the
DC NVEs for the multi-homing functions, ES routes will be advertised
so that ES discovery and Designated Forwarder (DF) procedures can be
followed. The MAC addresses learned (in the data plane) on the hand-
off links will be advertised with the I-ESI encoded in the ESI field.
3.5. Gateway Optimizations
The following GW features are optional and optimize the control plane
and data plane in the DC.
3.5.1. MAC Address Advertisement Control
The use of EVPN in NVO networks brings a significant number of
benefits as described in [EVPN-Overlays]. However, if multiple DCs
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are interconnected into a single EVI, each DC will have to import all
of the MAC addresses from each of the other DCs.
Even if optimized BGP techniques like RT-constraint [RFC4684] are
used, the number of MAC addresses to advertise or withdraw (in case
of failure) by the GWs of a given DC could overwhelm the NVEs within
that DC, particularly when the NVEs reside in the hypervisors.
The solution specified in this document uses the 'Unknown MAC Route'
(UMR) which is advertised into a given DC by each of the DC's GWs.
This route is defined in [RFC7543] and is a regular EVPN MAC/IP
Advertisement route in which the MAC Address Length is set to 48, the
MAC address is set to 0, and the ESI field is set to the DC GW's I-
ESI.
An NVE within that DC that understands and process the UMR will send
unknown unicast frames to one of the DCs GWs, which will then forward
that packet to the correct egress PE. Note that, because the ESI is
set to the DC GW's I-ESI, all-active multi-homing can be applied to
unknown unicast MAC addresses. An NVE that does not understand the
Unknown MAC route will handle unknown unicast as described in
[RFC7432].
This document proposes that local policy determines whether MAC
addresses and/or the UMR are advertised into a given DC. As an
example, when all the DC MAC addresses are learned in the
control/management plane, it may be appropriate to advertise only the
UMR. Advertising all the DC MAC addresses in the control/management
plane is usually the case when the NVEs reside in hypervisors. Refer
to [EVPN-Overlays] section 7.
It is worth noting that the UMR usage in [RFC7543] and the UMR usage
in this document are different. In the former, a Virtual Spoke (V-
spoke) does not necessarily learn all the MAC addresses pertaining to
hosts in other V-spokes of the same network. The communication
between two V-spokes is done through the DMG, until the V-spokes
learn each other's MAC addresses. In this document, two leaf switches
in the same DC are recommended to learn each other's MAC addresses
for the same EVI. The leaf to leaf communication is always direct and
does not go through the GW.
3.5.2. ARP/ND flooding control
Another optimization mechanism, naturally provided by EVPN in the
GWs, is the Proxy ARP/ND function. The GWs should build a Proxy
ARP/ND cache table as per [RFC7432]. When the active GW receives an
ARP/ND request/solicitation coming from the WAN, the GW does a Proxy
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ARP/ND table lookup and replies as long as the information is
available in its table.
This mechanism is especially recommended on the GWs, since it
protects the DC network from external ARP/ND-flooding storms.
3.5.3. Handling failures between GW and WAN Edge routers
Link/PE failures are handled on the GWs as specified in [RFC7432].
The GW detecting the failure will withdraw the EVPN routes as per
[RFC7432].
Individual AC/PW failures may be detected by OAM mechanisms. For
instance:
o If the Interconnect solution is based on a VLAN hand-off, Ethernet-
CFM [802.1AG][Y.1731] may be used to detect individual AC failures
on both, the GW and WAN Edge router. An individual AC failure will
trigger the withdrawal of the corresponding A-D per EVI route as
well as the MACs learned on that AC.
o If the Interconnect solution is based on a PW hand-off, the Label
Distribution Protocol (LDP) PW Status bits TLV [RFC6870] may be
used to detect individual PW failures on both, the GW and WAN Edge
router.
4. Integrated Interconnect solution for EVPN overlay networks
When the DC and the WAN are operated by the same administrative
entity, the Service Provider can decide to integrate the GW and WAN
Edge PE functions in the same router for obvious CAPEX and OPEX
saving reasons. This is illustrated in Figure 2. Note that this model
does not provide an explicit demarcation link between DC and WAN
anymore. Although not shown in Figure 2, note that the GWs may have
local ACs.
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+--+
|CE|
+--+
|
+----+
+----| PE |----+
+---------+ | +----+ | +---------+
+----+ | +---+ +---+ | +----+
|NVE1|--| | | | | |--|NVE3|
+----+ | |GW1| |GW3| | +----+
| +---+ +---+ |
| NVO-1 | WAN | NVO-2 |
| +---+ +---+ |
| | | | | |
+----+ | |GW2| |GW4| | +----+
|NVE2|--| +---+ +---+ |--|NVE4|
+----+ +---------+ | | +---------+ +----+
+--------------+
|<--EVPN-Overlay--->|<-----VPLS--->|<---EVPN-Overlay-->|
|<--PBB-VPLS-->|
Interconnect -> |<-EVPN-MPLS-->|
options |<--EVPN-Ovl-->|*
|<--PBB-EVPN-->|
Figure 2 Integrated Interconnect model
* EVPN-Ovl stands for EVPN-Overlay (and it's an Interconnect option).
4.1. Interconnect requirements
The Integrated Interconnect solution meets the following
requirements:
o Control plane and data plane interworking between the EVPN-overlay
network and the L2VPN technology supported in the WAN, irrespective
of the technology choice, i.e. (PBB-)VPLS or (PBB-)EVPN, as
depicted in Figure 2.
o Multi-homing, including single-active multi-homing with per-service
load balancing or all-active multi-homing, i.e. per-flow load-
balancing, as long as the technology deployed in the WAN supports
it.
o Support for end-to-end MAC Mobility, Static MAC protection and
other procedures (e.g. proxy-arp) described in [RFC7432] as long as
EVPN-MPLS is the technology of choice in the WAN.
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o Independent inclusive multicast trees in the WAN and in the DC.
That is, the inclusive multicast tree type defined in the WAN does
not need to be the same as in the DC.
4.2. VPLS Interconnect for EVPN-Overlay networks
4.2.1. Control/Data Plane setup procedures on the GWs
Regular MPLS tunnels and TLDP/BGP sessions will be setup to the WAN
PEs and RRs as per [RFC4761], [RFC4762], [RFC6074] and overlay
tunnels and EVPN will be setup as per [EVPN-Overlays]. Note that
different route-targets for the DC and for the WAN are normally
required (unless [RFC4762] is used in the WAN, in which case no WAN
route-target is needed). A single type-1 RD per service may be used.
In order to support multi-homing, the GWs will be provisioned with an
I-ESI (see section 3.4), that will be unique per interconnection. The
I-ES in this case will represent the group of PWs to the WAN PEs and
GWs. All the [RFC7432] procedures are still followed for the I-ES,
e.g. any MAC address learned from the WAN will be advertised to the
DC with the I-ESI in the ESI field.
A MAC-VRF per EVI will be created in each GW. The MAC-VRF will have
two different types of tunnel bindings instantiated in two different
split-horizon-groups:
o VPLS PWs will be instantiated in the "WAN split-horizon-group".
o Overlay tunnel bindings (e.g. VXLAN, NVGRE) will be instantiated
in the "DC split-horizon-group".
Attachment circuits are also supported on the same MAC-VRF (although
not shown in Figure 2), but they will not be part of any of the above
split-horizon-groups.
Traffic received in a given split-horizon-group will never be
forwarded to a member of the same split-horizon-group.
As far as BUM flooding is concerned, a flooding list will be composed
of the sub-list created by the inclusive multicast routes and the
sub-list created for VPLS in the WAN. BUM frames received from a
local Attachment Circuit (AC) will be forwarded to the flooding list.
BUM frames received from the DC or the WAN will be forwarded to the
flooding list observing the split-horizon-group rule described above.
Note that the GWs are not allowed to have an EVPN binding and a PW to
the same far-end within the same MAC-VRF, so that loops and packet
duplication are avoided. In case a GW can successfully establish
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both, an EVPN binding and a PW to the same far-end PE, the EVPN
binding will prevail and the PW will be brought operationally down.
The optimizations procedures described in section 3.5 can also be
applied to this model.
4.2.2. Multi-homing procedures on the GWs
This model supports single-active multi-homing on the GWs. All-active
multi-homing is not supported by VPLS, therefore it cannot be used on
the GWs.
In this case, for a given EVI, all the PWs in the WAN split-horizon-
group are assigned to I-ES. All the single-active multi-homing
procedures as described by [EVPN-Overlays] will be followed for the
I-ES.
The non-DF GW for the I-ES will block the transmission and reception
of all the PWs in the "WAN split-horizon-group" for BUM and unicast
traffic.
4.3. PBB-VPLS Interconnect for EVPN-Overlay networks
4.3.1. Control/Data Plane setup procedures on the GWs
In this case, there is no impact on the procedures described in
[RFC7041] for the B-component. However the I-component instances
become EVI instances with EVPN-Overlay bindings and potentially local
attachment circuits. A number of MAC-VRF instances can be multiplexed
into the same B-component instance. This option provides significant
savings in terms of PWs to be maintained in the WAN.
The I-ESI concept described in section 4.2.1 will also be used for
the PBB-VPLS-based Interconnect.
B-component PWs and I-component EVPN-overlay bindings established to
the same far-end will be compared. The following rules will be
observed:
o Attempts to setup a PW between the two GWs within the B-
component context will never be blocked.
o If a PW exists between two GWs for the B-component and an
attempt is made to setup an EVPN binding on an I-component linked
to that B-component, the EVPN binding will be kept operationally
down. Note that the BGP EVPN routes will still be valid but not
used.
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o The EVPN binding will only be up and used as long as there is no
PW to the same far-end in the corresponding B-component. The EVPN
bindings in the I-components will be brought down before the PW in
the B-component is brought up.
The optimizations procedures described in section 3.5 can also be
applied to this Interconnect option.
4.3.2. Multi-homing procedures on the GWs
This model supports single-active multi-homing on the GWs. All-active
multi-homing is not supported by this scenario.
The single-active multi-homing procedures as described by [EVPN-
Overlays] will be followed for the I-ES for each EVI instance
connected to the B-component. Note that in this case, for a given
EVI, all the EVPN bindings in the I-component are assigned to the I-
ES. The non-DF GW for the I-ES will block the transmission and
reception of all the I-component EVPN bindings for BUM and unicast
traffic. When learning MACs from the WAN, the non-DF MUST NOT
advertise EVPN MAC/IP routes for those MACs.
4.4. EVPN-MPLS Interconnect for EVPN-Overlay networks
If EVPN for MPLS tunnels, EVPN-MPLS hereafter, is supported in the
WAN, an end-to-end EVPN solution can be deployed. The following
sections describe the proposed solution as well as the impact
required on the [RFC7432] procedures.
4.4.1. Control Plane setup procedures on the GWs
The GWs MUST establish separate BGP sessions for sending/receiving
EVPN routes to/from the DC and to/from the WAN. Normally each GW will
setup one BGP EVPN session to the DC RR (or two BGP EVPN sessions if
there are redundant DC RRs) and one session to the WAN RR (or two
sessions if there are redundant WAN RRs).
In order to facilitate separate BGP processes for DC and WAN, EVPN
routes sent to the WAN SHOULD carry a different route-distinguisher
(RD) than the EVPN routes sent to the DC. In addition, although
reusing the same value is possible, different route-targets are
expected to be handled for the same EVI in the WAN and the DC. Note
that the EVPN service routes sent to the DC RRs will normally include
a [TUNNEL-ENCAP] BGP encapsulation extended community with a
different tunnel type than the one sent to the WAN RRs.
As in the other discussed options, an I-ES and its assigned I-ESI
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will be configured on the GWs for multi-homing. This I-ES represents
the WAN EVPN-MPLS PEs to the DC but also the DC EVPN-Overlay NVEs to
the WAN. Optionally, different I-ESI values are configured for
representing the WAN and the DC. If different EVPN-Overlay networks
are connected to the same group of GWs, each EVPN-Overlay network
MUST get assigned a different I-ESI.
Received EVPN routes will never be reflected on the GWs but consumed
and re-advertised (if needed):
o Ethernet A-D routes, ES routes and Inclusive Multicast routes
are consumed by the GWs and processed locally for the
corresponding [RFC7432] procedures.
o MAC/IP advertisement routes will be received, imported and if
they become active in the MAC-VRF, the information will be re-
advertised as new routes with the following fields:
+ The RD will be the GW's RD for the MAC-VRF.
+ The ESI will be set to the I-ESI.
+ The Ethernet-tag value will be kept from the received NLRI.
+ The MAC length, MAC address, IP Length and IP address values
will be kept from the received NLRI.
+ The MPLS label will be a local 20-bit value (when sent to the
WAN) or a DC-global 24-bit value (when sent to the DC for
encapsulations using a VNI).
+ The appropriate Route-Targets (RTs) and [TUNNEL-ENCAP] BGP
Encapsulation extended community will be used according to
[EVPN-Overlays].
The GWs will also generate the following local EVPN routes that will
be sent to the DC and WAN, with their corresponding RTs and [TUNNEL-
ENCAP] BGP Encapsulation extended community values:
o ES route(s) for the I-ESI(s).
o Ethernet A-D routes per ES and EVI for the I-ESI(s). The A-D
per-EVI routes sent to the WAN and the DC will have consistent
Ethernet-Tag values.
o Inclusive Multicast routes with independent tunnel type value
for the WAN and DC. E.g. a P2MP LSP may be used in the WAN
whereas ingress replication may be used in the DC. The routes
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sent to the WAN and the DC will have a consistent Ethernet-Tag.
o MAC/IP advertisement routes for MAC addresses learned in local
attachment circuits. Note that these routes will not include the
I-ESI, but ESI=0 or different from 0 for local multi-homed
Ethernet Segments (ES). The routes sent to the WAN and the DC
will have a consistent Ethernet-Tag.
Assuming GW1 and GW2 are peer GWs of the same DC, each GW will
generate two sets of the above local service routes: Set-DC will be
sent to the DC RRs and will include A-D per EVI, Inclusive Multicast
and MAC/IP routes for the DC encapsulation and RT. Set-WAN will be
sent to the WAN RRs and will include the same routes but using the
WAN RT and encapsulation. GW1 and GW2 will receive each other's set-
DC and set-WAN. This is the expected behavior on GW1 and GW2 for
locally generated routes:
o Inclusive multicast routes: when setting up the flooding lists
for a given MAC-VRF, each GW will include its DC peer GW only in
the EVPN-MPLS flooding list (by default) and not the EVPN-
Overlay flooding list. That is, GW2 will import two Inclusive
Multicast routes from GW1 (from set-DC and set-WAN) but will
only consider one of the two, having the set-WAN route higher
priority. An administrative option MAY change this preference so
that the set-DC route is selected first.
o MAC/IP advertisement routes for local attachment circuits: as
above, the GW will select only one, having the route from the
set-WAN a higher priority. As with the Inclusive multicast
routes, an administrative option MAY change this priority.
4.4.2. Data Plane setup procedures on the GWs
The procedure explained at the end of the previous section will make
sure there are no loops or packet duplication between the GWs of the
same EVPN-Overlay network (for frames generated from local ACs) since
only one EVPN binding per EVI (or per Ethernet Tag in case of VLAN-
aware bundle services) will be setup in the data plane between the
two nodes. That binding will by default be added to the EVPN-MPLS
flooding list.
As for the rest of the EVPN tunnel bindings, they will be added to
one of the two flooding lists that each GW sets up for the same MAC-
VRF:
o EVPN-overlay flooding list (composed of bindings to the remote
NVEs or multicast tunnel to the NVEs).
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o EVPN-MPLS flooding list (composed of MP2P or LSM tunnel to the
remote PEs)
Each flooding list will be part of a separate split-horizon-group:
the WAN split-horizon-group or the DC split-horizon-group. Traffic
generated from a local AC can be flooded to both
split-horizon-groups. Traffic from a binding of a split-horizon-group
can be flooded to the other split-horizon-group and local ACs, but
never to a member of its own split-horizon-group.
When either GW1 or GW2 receive a BUM frame on an MPLS tunnel
including an ESI label at the bottom of the stack, they will perform
an ESI label lookup and split-horizon filtering as per [RFC7432] in
case the ESI label identifies a local ESI (I-ESI or any other non-
zero ESI).
4.4.3. Multi-homing procedure extensions on the GWs
This model supports single-active as well as all-active multi-homing.
All the [RFC7432] multi-homing procedures for the DF election on I-
ES(s) as well as the backup-path (single-active) and aliasing (all-
active) procedures will be followed on the GWs. Remote PEs in the
EVPN-MPLS network will follow regular [RFC7432] aliasing or backup-
path procedures for MAC/IP routes received from the GWs for the same
I-ESI. So will NVEs in the EVPN-Overlay network for MAC/IP routes
received with the same I-ESI.
As far as the forwarding plane is concerned, by default, the EVPN-
Overlay network will have an analogous behavior to the access ACs in
[RFC7432] multi-homed Ethernet Segments.
The forwarding behavior on the GWs is described below:
o Single-active multi-homing; assuming a WAN split-horizon-group
(comprised of EVPN-MPLS bindings), a DC split-horizon-group
(comprised of EVPN-Overlay bindings) and local ACs on the GWs:
+ Forwarding behavior on the non-DF: the non-DF MUST block
ingress and egress forwarding on the EVPN-Overlay bindings
associated to the I-ES. The EVPN-MPLS network is considered to
be the core network and the EVPN-MPLS bindings to the remote
PEs and GWs will be active.
+ Forwarding behavior on the DF: the DF MUST NOT forward BUM or
unicast traffic received from a given split-horizon-group to a
member of his own split-horizon group. Forwarding to other
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split-horizon-groups and local ACs is allowed (as long as the
ACs are not part of an ES for which the node is non-DF). As
per [RFC7432] and for split-horizon purposes, when receiving
BUM traffic on the EVPN-Overlay bindings associated to an I-
ES, the DF GW SHOULD add the I-ESI label when forwarding to
the peer GW over EVPN-MPLS.
+ When receiving EVPN MAC/IP routes from the WAN, the non-DF
MUST NOT re-originate the EVPN routes and advertise them to
the DC peers. In the same way, EVPN MAC/IP routes received
from the DC MUST NOT be advertised to the WAN peers. This is
consistent with [RFC7432] and allows the remote PE/NVEs know
who the primary GW is, based on the reception of the MAC/IP
routes.
o All-active multi-homing; assuming a WAN split-horizon-group
(comprised of EVPN-MPLS bindings), a DC split-horizon-group
(comprised of EVPN-Overlay bindings) and local ACs on the GWs:
+ Forwarding behavior on the non-DF: the non-DF follows the same
behavior as the non-DF in the single-active case but only for
BUM traffic. Unicast traffic received from a split-horizon-
group MUST NOT be forwarded to a member of its own split-
horizon-group but can be forwarded normally to the other
split-horizon-groups and local ACs. If a known unicast packet
is identified as a "flooded" packet, the procedures for BUM
traffic MUST be followed.
+ Forwarding behavior on the DF: the DF follows the same
behavior as the DF in the single-active case but only for BUM
traffic. Unicast traffic received from a split-horizon-group
MUST NOT be forwarded to a member of its own split-horizon-
group but can be forwarded normally to the other split-
horizon-group and local ACs. If a known unicast packet is
identified as a "flooded" packet, the procedures for BUM
traffic MUST be followed. As per [RFC7432] and for split-
horizon purposes, when receiving BUM traffic on the EVPN-
Overlay bindings associated to an I-ES, the DF GW MUST add the
I-ESI label when forwarding to the peer GW over EVPN-MPLS.
+ Contrary to the single-active multi-homing case, both DF and
non-DF re-originate and advertise MAC/IP routes received from
the WAN/DC peers, adding the corresponding I-ESI so that the
remote PE/NVEs can perform regular aliasing as per [RFC7432].
The example in Figure 3 illustrates the forwarding of BUM traffic
originated from an NVE on a pair of all-active multi-homing GWs.
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|<--EVPN-Overlay--->|<--EVPN-MPLS-->|
+---------+ +--------------+
+----+ BUM +---+ |
|NVE1+----+----> | +-+-----+ |
+----+ | | DF |GW1| | | |
| | +-+-+ | | ++--+
| | | | +--> |PE1|
| +--->X +-+-+ | ++--+
| NDF| | | |
+----+ | |GW2<-+ |
|NVE2+--+ +-+-+ |
+----+ +--------+ | +------------+
v
+--+
|CE|
+--+
Figure 3 Multi-homing BUM forwarding
GW2 is the non-DF for the I-ES and blocks the BUM forwarding. GW1 is
the DF and forwards the traffic to PE1 and GW2. Packets sent to GW2
will include the ESI-label for the I-ES. Based on the ESI-label, GW2
identifies the packets as I-ES-generated packets and will only
forward them to local ACs (CE in the example) and not back to the
EVPN-Overlay network.
4.4.4. Impact on MAC Mobility procedures
MAC Mobility procedures described in [RFC7432] are not modified by
this document.
Note that an intra-DC MAC move still leaves the MAC attached to the
same I-ES, so under the rules of [RFC7432] this is not considered a
MAC mobility event. Only when the MAC moves from the WAN domain to
the DC domain (or from one DC to another) the MAC will be learned
from a different ES and the MAC Mobility procedures will kick in.
The sticky bit indication in the MAC Mobility extended community MUST
be propagated between domains.
4.4.5. Gateway optimizations
All the Gateway optimizations described in section 3.5 MAY be applied
to the GWs when the Interconnect is based on EVPN-MPLS.
In particular, the use of the Unknown MAC Route, as described in
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section 3.5.1, solves some transient packet duplication issues in
cases of all-active multi-homing, as explained below.
Consider the diagram in Figure 2 for EVPN-MPLS Interconnect and all-
active multi-homing, and the following sequence:
a) MAC Address M1 is advertised from NVE3 in EVI-1.
b) GW3 and GW4 learn M1 for EVI-1 and re-advertise M1 to the WAN
with I-ESI-2 in the ESI field.
c) GW1 and GW2 learn M1 and install GW3/GW4 as next-hops following
the EVPN aliasing procedures.
d) Before NVE1 learns M1, a packet arrives at NVE1 with
destination M1. If the Unknown MAC Route had not been
advertised into the DC, NVE1 would have flooded the packet
throughout the DC, in particular to both GW1 and GW2. If the
same VNI/VSID is used for both known unicast and BUM traffic,
as is typically the case, there is no indication in the packet
that it is a BUM packet and both GW1 and GW2 would have
forwarded it, creating packet duplication. However, because the
Unknown MAC Route had been advertised into the DC, NVE1 will
unicast the packet to either GW1 or GW2.
e) Since both GW1 and GW2 know M1, the GW receiving the packet
will forward it to either GW3 or GW4.
4.4.6. Benefits of the EVPN-MPLS Interconnect solution
The [EVPN-Overlays] "DCI using ASBRs" solution and the GW solution
with EVPN-MPLS Interconnect may be seen similar since they both
retain the EVPN attributes between Data Centers and throughout the
WAN. However the EVPN-MPLS Interconnect solution on the GWs has
significant benefits compared to the "DCI using ASBRs" solution:
o As in any of the described GW models, this solution supports the
connectivity of local attachment circuits on the GWs. This is
not possible in a "DCI using ASBRs" solution.
o Different data plane encapsulations can be supported in the DC
and the WAN, while a uniform encapsulation is needed in the "DCI
using ASBRs" solution.
o Optimized multicast solution, with independent inclusive
multicast trees in DC and WAN.
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o MPLS Label aggregation: for the case where MPLS labels are
signaled from the NVEs for MAC/IP Advertisement routes, this
solution provides label aggregation. A remote PE MAY receive a
single label per GW MAC-VRF as opposed to a label per NVE/MAC-
VRF connected to the GW MAC-VRF. For instance, in Figure 2, PE
would receive only one label for all the routes advertised for a
given MAC-VRF from GW1, as opposed to a label per NVE/MAC-VRF.
o The GW will not propagate MAC mobility for the MACs moving
within a DC. Mobility intra-DC is solved by all the NVEs in the
DC. The MAC Mobility procedures on the GWs are only required in
case of mobility across DCs.
o Proxy-ARP/ND function on the DC GWs can be leveraged to reduce
ARP/ND flooding in the DC or/and in the WAN.
4.5. PBB-EVPN Interconnect for EVPN-Overlay networks
PBB-EVPN [RFC7623] is yet another Interconnect option. It requires
the use of GWs where I-components and associated B-components are
part of EVI instances.
4.5.1. Control/Data Plane setup procedures on the GWs
EVPN will run independently in both components, the I-component MAC-
VRF and B-component MAC-VRF. Compared to [RFC7623], the DC C-MACs are
no longer learned in the data plane on the GW but in the control
plane through EVPN running on the I-component. Remote C-MACs coming
from remote PEs are still learned in the data plane. B-MACs in the B-
component will be assigned and advertised following the procedures
described in [RFC7623].
An I-ES will be configured on the GWs for multi-homing, but its I-ESI
will only be used in the EVPN control plane for the I-component EVI.
No non-reserved ESIs will be used in the control plane of the B-
component EVI as per [RFC7623], that is, the I-ES will be represented
to the WAN PBB-EVPN PEs using shared or dedicated B-MACs.
The rest of the control plane procedures will follow [RFC7432] for
the I-component EVI and [RFC7623] for the B-component EVI.
From the data plane perspective, the I-component and B-component EVPN
bindings established to the same far-end will be compared and the I-
component EVPN-overlay binding will be kept down following the rules
described in section 4.3.1.
4.5.2. Multi-homing procedures on the GWs
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This model supports single-active as well as all-active multi-homing.
The forwarding behavior of the DF and non-DF will be changed based on
the description outlined in section 4.4.3, only replacing the "WAN
split-horizon-group" for the B-component, and using [RFC7623]
procedures for the traffic sent or received on the B-component.
4.5.3. Impact on MAC Mobility procedures
C-MACs learned from the B-component will be advertised in EVPN within
the I-component EVI scope. If the C-MAC was previously known in the
I-component database, EVPN would advertise the C-MAC with a higher
sequence number, as per [RFC7432]. From a Mobility perspective and
the related procedures described in [RFC7432], the C-MACs learned
from the B-component are considered local.
4.5.4. Gateway optimizations
All the considerations explained in section 4.4.5 are applicable to
the PBB-EVPN Interconnect option.
4.6. EVPN-VXLAN Interconnect for EVPN-Overlay networks
If EVPN for Overlay tunnels is supported in the WAN and a GW function
is required, an end-to-end EVPN solution can be deployed. While
multiple Overlay tunnel combinations at the WAN and the DC are
possible (MPLSoGRE, nvGRE, etc.), VXLAN is described here, given its
popularity in the industry. This section focuses on the specific case
of EVPN for VXLAN (EVPN-VXLAN hereafter) and the impact on the
[RFC7432] procedures.
The procedures described in section 4.4 apply to this section too,
only replacing EVPN-MPLS for EVPN-VXLAN control plane specifics and
using [EVPN-Overlays] "Local Bias" procedures instead of section
4.4.3. Since there are no ESI-labels in VXLAN, GWs need to rely on
"Local Bias" to apply split-horizon on packets generated from the I-
ES and sent to the peer GW.
This use-case assumes that NVEs need to use the VNIs or VSIDs as a
globally unique identifiers within a data center, and a Gateway needs
to be employed at the edge of the data center network to translate
the VNI or VSID when crossing the network boundaries. This GW
function provides VNI and tunnel IP address translation. The use-case
in which local downstream assigned VNIs or VSIDs can be used (like
MPLS labels) is described by [EVPN-Overlays].
While VNIs are globally significant within each DC, there are two
possibilities in the Interconnect network:
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a) Globally unique VNIs in the Interconnect network:
In this case, the GWs and PEs in the Interconnect network will
agree on a common VNI for a given EVI. The RT to be used in the
Interconnect network can be auto-derived from the agreed
Interconnect VNI. The VNI used inside each DC MAY be the same
as the Interconnect VNI.
b) Downstream assigned VNIs in the Interconnect network.
In this case, the GWs and PEs MUST use the proper RTs to
import/export the EVPN routes. Note that even if the VNI is
downstream assigned in the Interconnect network, and unlike
option (a), it only identifies the <Ethernet Tag, GW> pair and
not the <Ethernet Tag, egress PE> pair. The VNI used inside
each DC MAY be the same as the Interconnect VNI. GWs SHOULD
support multiple VNI spaces per EVI (one per Interconnect
network they are connected to).
In both options, NVEs inside a DC only have to be aware of a single
VNI space, and only GWs will handle the complexity of managing
multiple VNI spaces. In addition to VNI translation above, the GWs
will provide translation of the tunnel source IP for the packets
generated from the NVEs, using their own IP address. GWs will use
that IP address as the BGP next-hop in all the EVPN updates to the
Interconnect network.
The following sections provide more details about these two options.
4.6.1. Globally unique VNIs in the Interconnect network
Considering Figure 2, if a host H1 in NVO-1 needs to communicate with
a host H2 in NVO-2, and assuming that different VNIs are used in each
DC for the same EVI, e.g. VNI-10 in NVO-1 and VNI-20 in NVO-2, then
the VNIs MUST be translated to a common Interconnect VNI (e.g. VNI-
100) on the GWs. Each GW is provisioned with a VNI translation
mapping so that it can translate the VNI in the control plane when
sending BGP EVPN route updates to the Interconnect network. In other
words, GW1 and GW2 MUST be configured to map VNI-10 to VNI-100 in the
BGP update messages for H1's MAC route. This mapping is also used to
translate the VNI in the data plane in both directions, that is, VNI-
10 to VNI-100 when the packet is received from NVO-1 and the reverse
mapping from VNI-100 to VNI-10 when the packet is received from the
remote NVO-2 network and needs to be forwarded to NVO-1.
The procedures described in section 4.4 will be followed, considering
that the VNIs advertised/received by the GWs will be translated
accordingly.
4.6.2. Downstream assigned VNIs in the Interconnect network
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In this case, if a host H1 in NVO-1 needs to communicate with a host
H2 in NVO-2, and assuming that different VNIs are used in each DC for
the same EVI, e.g. VNI-10 in NVO-1 and VNI-20 in NVO-2, then the VNIs
MUST be translated as in section 4.6.1. However, in this case, there
is no need to translate to a common Interconnect VNI on the GWs. Each
GW can translate the VNI received in an EVPN update to a locally
assigned VNI advertised to the Interconnect network. Each GW can use
a different Interconnect VNI, hence this VNI does not need to be
agreed on all the GWs and PEs of the Interconnect network.
The procedures described in section 4.4 will be followed, taking the
considerations above for the VNI translation.
5. Security Considerations
This document applies existing specifications to a number of
Interconnect models. The Security Considerations included in those
documents, such as [RFC7432], [EVPN-Overlays], [RFC7623], [RFC4761]
and [RFC4762] apply to this document whenever those technologies are
used.
As discussed, [EVPN-Overlays] discusses two main DCI solution groups:
"DCI using GWs" and "DCI using ASBRs". This document specifies the
solutions that correspond to the "DCI using GWs" group. It is
important to note that the use of GWs provide a superior level of
security on a per tenant basis, compared to the use of ASBRs. This is
due to the fact that GWs need to perform a MAC lookup on the frames
being received from the WAN, and they apply security procedures, such
as filtering of undesired frames, filtering of frames with a source
MAC that matches a protected MAC in the DC or application of MAC
duplication procedures defined in [RFC7432]. On ASBRs though, traffic
is forwarded based on a label or VNI swap and there is usually no
visibility of the encapsulated frames, which can carry malicious
traffic.
In addition, the GW optimizations specified in this document, provide
additional protection of the DC Tenant Systems. For instance, the MAC
address advertisement control and Unknown MAC Route defined in
section 3.5.1 protect the DC NVEs from being overwhelmed with an
excessive number MAC/IP routes being learned on the GWs from the WAN.
The ARP/ND flooding control described in 3.5.2 can reduce/suppress
broadcast storms being injected from the WAN.
Finally, the reader should be aware of the potential security
implications of designing a DCI with the Decoupled Interconnect
solution (section 3) or the Integrated Interconnect solution (section
4). In the Decoupled Interconnect solution the DC is typically easier
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to protect from the WAN, since each GW has a single logical link to
one WAN PE, whereas in the Integrated solution, the GW has logical
links to all the WAN PEs that are attached to the tenant. In either
model, proper control plane and data plane policies should be put in
place in the GWs in order to protect the DC from potential attacks
coming from the WAN.
6. IANA Considerations
This document has no IANA actions.
7. References
7.1. Normative References
[RFC4761] Kompella, K., Ed., and Y. Rekhter, Ed., "Virtual Private
LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling",
RFC 4761, DOI 10.17487/RFC4761, January 2007, <http://www.rfc-
editor.org/info/rfc4761>.
[RFC4762] Lasserre, M., Ed., and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
<http://www.rfc-editor.org/info/rfc4762>.
[RFC6074] Rosen, E., Davie, B., Radoaca, V., and W. Luo,
"Provisioning, Auto-Discovery, and Signaling in Layer 2 Virtual
Private Networks (L2VPNs)", RFC 6074, DOI 10.17487/RFC6074, January
2011, <http://www.rfc-editor.org/info/rfc6074>.
[RFC7041] Balus, F., Ed., Sajassi, A., Ed., and N. Bitar, Ed.,
"Extensions to the Virtual Private LAN Service (VPLS) Provider Edge
(PE) Model for Provider Backbone Bridging", RFC 7041, DOI
10.17487/RFC7041, November 2013, <http://www.rfc-
editor.org/info/rfc7041>.
[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, <http://www.rfc-
editor.org/info/rfc7432>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March
1997, <http://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
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2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017,
<http://www.rfc-editor.org/info/rfc8174>.
[TUNNEL-ENCAP] Rosen et al., "The BGP Tunnel Encapsulation
Attribute", draft-ietf-idr-tunnel-encaps-08, work in progress,
January 11, 2018.
[RFC7623] Sajassi et al., "Provider Backbone Bridging Combined with
Ethernet VPN (PBB-EVPN)", RFC 7623, September, 2015, <http://www.rfc-
editor.org/info/rfc7623>.
[EVPN-Overlays] Sajassi-Drake et al., "A Network Virtualization
Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-11.txt,
work in progress, January 2018.
[RFC7543] Jeng, H., Jalil, L., Bonica, R., Patel, K., and L. Yong,
"Covering Prefixes Outbound Route Filter for BGP-4", RFC 7543, DOI
10.17487/RFC7543, May 2015, <https://www.rfc-
editor.org/info/rfc7543>.
7.2. Informative References
[RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk,
R., Patel, K., and J. Guichard, "Constrained Route Distribution for
Border Gateway Protocol/MultiProtocol Label Switching (BGP/MPLS)
Internet Protocol (IP) Virtual Private Networks (VPNs)", RFC 4684,
DOI 10.17487/RFC4684, November 2006, <http://www.rfc-
editor.org/info/rfc4684>.
[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, <http://www.rfc-
editor.org/info/rfc7348>.
[RFC7637] Garg, P., et al., "NVGRE: Network Virtualization using
Generic Routing Encapsulation", RFC 7637, September, 2015
[RFC4023] Worster, T., Rekhter, Y., and E. Rosen, Ed.,
"Encapsulating MPLS in IP or Generic Routing Encapsulation (GRE)",
RFC 4023, DOI 10.17487/RFC4023, March 2005, <http://www.rfc-
editor.org/info/rfc4023>.
[Y.1731] ITU-T Recommendation Y.1731, "OAM functions and mechanisms
for Ethernet based networks", July 2011.
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[802.1AG] IEEE 802.1AG_2007, "IEEE Standard for Local and
Metropolitan Area Networks - Virtual Bridged Local Area Networks
Amendment 5: Connectivity Fault Management", January 2008.
[802.1Q-2014] IEEE 802.1Q-2014, "IEEE Standard for Local and
metropolitan area networks--Bridges and Bridged Networks", December
2014.
[RFC6870] Muley, P., Ed., and M. Aissaoui, Ed., "Pseudowire
Preferential Forwarding Status Bit", RFC 6870, DOI 10.17487/RFC6870,
February 2013, <http://www.rfc-editor.org/info/rfc6870>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, DOI 10.17487/RFC3031,
January 2001, <http://www.rfc-editor.org/info/rfc3031>.
[VIRTUAL-ES] Sajassi et al., "EVPN Virtual Ethernet Segment", draft-
sajassi-bess-evpn-virtual-eth-segment-03, work in progress, February
2018.
8. Acknowledgments
The authors would like to thank Neil Hart, Vinod Prabhu and Kiran
Nagaraj for their valuable comments and feedback. We would also like
to thank Martin Vigoureux and Alvaro Retana for his detailed review
and comments.
9. Contributors
In addition to the authors listed on the front page, the following
co-authors have also contributed to this document:
Ravi Shekhar
Anil Lohiya
Wen Lin
Juniper Networks
Florin Balus
Patrice Brissette
Cisco
Senad Palislamovic
Nokia
Dennis Cai
Alibaba
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10. Authors' Addresses
Jorge Rabadan
Nokia
777 E. Middlefield Road
Mountain View, CA 94043 USA
Email: jorge.rabadan@nokia.com
Senthil Sathappan
Nokia
Email: senthil.sathappan@nokia.com
Wim Henderickx
Nokia
Email: wim.henderickx@nokia.com
Ali Sajassi
Cisco
Email: sajassi@cisco.com
John Drake
Juniper
Email: jdrake@juniper.net
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