Документ взят из кэша поисковой машины. Адрес оригинального документа : http://mirror.msu.net/pub/rfc-editor/internet-drafts/draft-boutros-bess-vxlan-evpn-01.txt Дата изменения: Thu Mar 17 03:18:06 2016 Дата индексирования: Sun Apr 10 07:18:12 2016 Кодировка: Поисковые слова: horizon

INTERNET-DRAFT Sami Boutros
Intended Status: Informational VMware

Ali Sajassi
Samer Salam
Dennis Cai
Samir Thoria
Cisco Systems

Tapraj Singh
John Drake
Juniper Networks

Jeff Tantsura
Ericsson

Expires: September 17, 2016 March 16, 2016


VXLAN DCI Using EVPN
draft-boutros-bess-vxlan-evpn-01.txt


Abstract

This document describes how Ethernet VPN (E-VPN) technology can be
used to interconnect VXLAN or NVGRE networks over an MPLS/IP network.
This is to provide intra-subnet connectivity at Layer 2 and control-
plane separation among the interconnected VXLAN or NVGRE networks.
The scope of the learning of host MAC addresses in VXLAN or NVGRE
network is limited to data plane learning in this document.

Status of this Memo

This Internet-Draft is submitted to IETF 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.

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."

The list of current Internet-Drafts can be accessed at



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http://www.ietf.org/1id-abstracts.html

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html


Copyright and License Notice

Copyright (c) 2016 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.


Table of Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Control Plane Separation among VXLAN/NVGRE Networks . . . . 4
2.2 All-Active Multi-homing . . . . . . . . . . . . . . . . . . 5
2.3 Layer 2 Extension of VNIs/VSIDs over the MPLS/IP Network . . 5
2.4 Support for Integrated Routing and Bridging (IRB) . . . . . 5
3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Redundancy and All-Active Multi-homing . . . . . . . . . . 6
4. EVPN Routes . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. BGP MAC Advertisement Route . . . . . . . . . . . . . . . 7
4.2. Ethernet Auto-Discovery Route . . . . . . . . . . . . . . 8
4.3. Per VPN Route Targets . . . . . . . . . . . . . . . . . . 8
4.4 Inclusive Multicast Route . . . . . . . . . . . . . . . . . 8
4.5. Unicast Forwarding . . . . . . . . . . . . . . . . . . . . 8
4.6. Handling Multicast . . . . . . . . . . . . . . . . . . . . 9
4.6.2. Multicast Stitching with Per-VNI Load Balancing . . . . 9
4.6.2.1 PIM SM operation . . . . . . . . . . . . . . . . . . 10
5. NVGRE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6. Use Cases Overview . . . . . . . . . . . . . . . . . . . . . . 11
6.1. Homogeneous Network DCI interconnect Use cases . . . . . . 12
6.1.1. VNI Base Mode EVPN Service Use Case . . . . . . . . . . 12
6.1.2. VNI Bundle Service Use Case Scenario . . . . . . . . . 13
6.1.3. VNI Translation Use Case . . . . . . . . . . . . . . 13



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6.2. Heterogeneous Network DCI Use Cases Scenarios . . . . . . . 13
6.2.1. VXLAN VLAN Interworking Over EVPN Use Case Scenario . . 13
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
10.1 Normative References . . . . . . . . . . . . . . . . . . . 14
10.2 Informative References . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15










































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1 Introduction

[EVPN] introduces a solution for multipoint L2VPN services, with
advanced multi-homing capabilities, using BGP control plane over the
core MPLS/IP network. [VXLAN] defines a tunneling scheme to overlay
Layer 2 networks on top of Layer 3 networks. [VXLAN] allows for
optimal forwarding of Ethernet frames with support for multipathing
of unicast and multicast traffic. VXLAN uses UDP/IP encapsulation for
tunneling.

In this document, we discuss how Ethernet VPN (EVPN) technology can
be used to interconnect VXLAN or NVGRE networks over an MPLS/IP
network. This is achieved by terminating the VxLAN tunnel at the
hand-off points, performing data plane MAC learning of customer
traffic and providing intra-subnet connectivity for the customers at
Layer 2 across the MPLS/IP core. The solution maintains control-plane
separation among the interconnected VXLAN or NVGRE networks. The
scope of the learning of host MAC addresses in VXLAN or NVGRE network
is limited to data plane learning in this document. The distribution
of MAC addresses in control plane using BGP in VXLAN or NVGRE network
is outside of the scope of this document and it is covered in [EVPN-
OVERLY].

1.1 Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].

LDP: Label Distribution Protocol. MAC: Media Access Control MPLS:
Multi Protocol Label Switching. OAM: Operations, Administration and
Maintenance. PE: Provide Edge Node. PW: PseudoWire. TLV: Type,
Length, and Value. VPLS: Virtual Private LAN Services. VXLAN: Virtual
eXtensible Local Area Network. VTEP: VXLAN Tunnel End Point VNI:
VXLAN Network Identifier (or VXLAN Segment ID) ToR: Top of Rack
switch. LACP: Link Aggregation Control Protocol

2. Requirements

2.1. Control Plane Separation among VXLAN/NVGRE Networks

It is required to maintain control-plane separation for the underlay
networks (e.g., among the various VXLAN/NVGRE networks) being
interconnected over the MPLS/IP network. This ensures the following
characteristics:

- scalability of the IGP control plane in large deployments and fault
domain localization, where link or node failures in one site do not



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trigger re-convergence in remote sites.

- scalability of multicast trees as the number of interconnected
networks scales.

2.2 All-Active Multi-homing

It is important to allow for all-active multi-homing of the
VXLAN/NVGRE network to MPLS/IP network where traffic from a VTEP can
arrive at any of the PEs and can be forwarded accordingly over the
MPLS/IP network. Furthermore, traffic destined to a VTEP can be
received over the MPLS/IP network at any of the PEs connected to the
VXLAN/NVGRE network and be forwarded accordingly. The solution MUST
support all-active multi-homing to an VXLAN/NVGRE network.

2.3 Layer 2 Extension of VNIs/VSIDs over the MPLS/IP Network

It is required to extend the VXLAN VNIs or NVGRE VSIDs over the
MPLS/IP network to provide intra-subnet connectivity between the
hosts (e.g. VMs) at Layer 2.

2.4 Support for Integrated Routing and Bridging (IRB)

The data center WAN edge node is required to support integrated
routing and bridging in order to accommodate both inter-subnet
routing and intra-subnet bridging for a given VNI/VSID. For example,
inter-subnet switching is required when a remote host connected to an
enterprise IP-VPN site wants to access an application resided on a
VM.

3. Solution Overview

Every VXLAN/NVGRE network, which is connected to the MPLS/IP core,
runs an independent instance of the IGP control-plane. Each PE
participates in the IGP control plane instance of its VXLAN/NVGRE
network.

Each PE node terminates the VXLAN or NVGRE data-plane encapsulation
where each VNI or VSID is mapped to a bridge-domain. The PE performs
data plane MAC learning on the traffic received from the VXLAN/NVGRE
network.

Each PE node implements EVPN or PBB-EVPN to distribute in BGP either
the client MAC addresses learnt over the VXLAN tunnel in case of
EVPN, or the PEs' B-MAC addresses in case of PBB-EVPN. In the PBB-
EVPN case, client MAC addresses will continue to be learnt in data
plane.




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Each PE node would encapsulate the Ethernet frames with MPLS when
sending the packets over the MPLS core and with the VXLAN or NVGRE
tunnel header when sending the packets over the VXLAN or NVGRE
Network.

+--------------+
| |
+---------+ +----+ MPLS +----+ +---------+
+-----+ | |---|PE1 | |PE3 |--| | +-----+
|VTEP1|--| | +----+ +----+ | |--|VTEP3|
+-----+ | VXLAN | +----+ +----+ | VXLAN | +-----+
+-----+ | |---|PE2 | |PE4 |--| | +-----+
|VTEP2|--| | +----+Backbone+----+ | |--|VTEP4|
+-----+ +---------+ +--------------+ +---------+ +-----+

|<--- Underlay IGP ---->|<-Overlay BGP->|<--- Underlay IGP --->| CP

|<----- VXLAN --------->||<------ VXLAN ------->| DP
|<----MPLS----->|


Legend: CP = Control Plane View DP = Data Plane View

Figure 1: Interconnecting VXLAN Networks with VXLAN-EVPN

3.1. Redundancy and All-Active Multi-homing

When a VXLAN network is multi-homed to two or more PEs, and provided
that these PEs have the same IGP distance to a given NVE, the
solution MUST support load-balancing of traffic between the NVE and
the MPLS network, among all the multi-homed PEs. This maximizes the
use of the bisectional bandwidth of the VXLAN network. One of the
main capabilities of EVPN/PBB-EVPN is the support for all-active
multi-homing, where the known unicast traffic to/from a multi-homed
site can be forwarded by any of the PEs attached to that site. This
ensures optimal usage of multiple paths and load balancing. EVPN/PBB-
EVPN, through its DF election and split-horizon filtering mechanisms,
ensures that no packet duplication or forwarding loops result in such
scenarios. In this solution, the VXLAN network is treated as a
multi-homed site for the purpose of EVPN operation.

Since the context of this solution is VXLAN networks with data-plane
learning paradigm, it is important for the multi-homing mechanism to
ensure stability of the MAC forwarding tables at the NVEs, while
supporting all-active forwarding at the PEs. For example, in Figure 1
above, if each PE uses a distinct IP address for its VTEP tunnel,
then for a given VNI, when an NVE learns a host's MAC address against
the originating VTEP source address, its MAC forwarding table will



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keep flip-flopping among the VTEP addresses of the local PEs. This is
because a flow associated with the same host MAC address can arrive
at any of the PE devices. In order to ensure that there is no
flip/flopping of MAC-to-VTEP address associations, an IP Anycast
address MUST be used as the VTEP address on all PEs multi-homed to a
given VXLAN network. The use of IP Anycast address has two
advantages:

a) It prevents any flip/flopping in the forwarding tables for the
MAC-to-VTEP associations

b) It enables load-balancing via ECMP for DCI traffic among the
multi-homed PEs

In the baseline [EVPN] draft, the all-active multi-homing is
described for a multi-homed device (MHD) using [LACP] and the single-
active multi-homing is described for a multi-homed network (MHN)
using [802.1Q]. In this draft, the all-active multi-homing is
described for a VXLAN MHN. This implies some changes to the filtering
which will be described in details in the multicast section (Section
4.6.2).

The filtering used for BUM traffic of all-active multi-homing in
[EVPN] is asymmetric; where the BUM traffic from the MPLS/IP network
towards the multi-homed site is filtered on non-DF PE(s) and it
passes thorough the DF PE. There is no filtering of BUM traffic
originating from the multi-homed site because of the use of Ethernet
Link Aggregation: the MHD hashes the BUM traffic to only a single
link. However, in this solution because BUM traffic can arrive at
both PEs in both core-to-site and site-to-core directions, the
filtering needs to be symmetric just like the filtering of BUM
traffic for single-active multi-homing (on a per service
instance/VLAN basis).

4. EVPN Routes

This solution leverages the same BGP Routes and Attributes defined in
[EVPN], adapted as follows:

4.1. BGP MAC Advertisement Route

This route and its associated modes are used to distribute the
customer MAC addresses learnt in data plane over the VXLAN tunnel in
case of EVPN. Or can be used to distribute the provider Backbone MAC
addresses in case of PBB-EVPN.

In case of EVPN, the Ethernet Tag ID of this route is set to zero for
VNI-based mode, where there is one-to-one mapping between a VNI and



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an EVI. In such case, there is no need to carry the VNI in the MAC
advertisement route because BD ID can be derived from the RT
associated with this route. However, for VNI-aware bundle mode, where
there is multiple VNIs can be mapped to the same EVI, the Ethernet
Tag ID MUST be set to the VNI. At the receiving PE, the BD ID is
derived from the combination of RT + VNI - e.g., the RT identifies
the associated EVI on that PE and the VNI identifies the
corresponding BD ID within that EVI.

The Ethernet Tag field can be set to a normalized value that maps to
the VNI, in VNI aware bundling services, this would make the VNI
value of local significance in multiple Data centers. Data plane need
to map to this normalized VNI value and have it on the IP VxLAN
packets exchanged between the DCIs.

4.2. Ethernet Auto-Discovery Route

When EVPN is used, the application of this route is as specified in
[EVPN]. However, when PBB-EVPN is used, there is no need for this
route per [PBB-EVPN].

4.3. Per VPN Route Targets

VXLAN-EVPN uses the same set of route targets defined in [EVPN].

4.4 Inclusive Multicast Route

The EVPN Inclusive Multicast route is used for auto-discovery of PE
devices participating in the same tenant virtual network identified
by a VNI over the MPLS network. It also enables the stitching of the
IP multicast trees, which are local to each VXLAN site, with the
Label Switched Multicast (LSM) trees of the MPLS network.

The Inclusive Multicast Route is encoded as follow:

- Ethernet Tag ID is set to zero for VNI-based mode and to VNI for
VNI-aware bundle mode.

- Originating Router's IP Address is set to one of the PE's IP
addresses.

All other fields are set as defined in [EVPN].

Please see section 4.6 "Handling Multicast"

4.5. Unicast Forwarding

Host MAC addresses will be learnt in data plane from the VXLAN



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network and associated with the corresponding VTEP identified by the
source IP address. Host MAC addresses will be learnt in control plane
if EVPN is implemented over the MPLS/IP core, or in the data-plane if
PBB-EVPN is implemented over the MPLS core. When Host MAC addressed
are learned in data plane over MPLS/IP core [in case of PBB-EVPN],
they are associated with their corresponding BMAC addresses.

L2 Unicast traffic destined to the VXLAN network will be encapsulated
with the IP/UDP header and the corresponding customer bridge VNI.

L2 Unicast traffic destined to the MPLS/IP network will be
encapsulated with the MPLS label.

4.6. Handling Multicast

Each VXLAN network independently builds its P2MP or MP2MP shared
multicast trees. A P2MP or MP2MP tree is built for one or more VNIs
local to the VXLAN network.

In the MPLS/IP network, multiple options are available for the
delivery of multicast traffic: - Ingress replication - LSM
with Inclusive trees - LSM with Aggregate Inclusive trees -
LSM with Selective trees - LSM with Aggregate Selective trees

When LSM is used, the trees are P2MP.

The PE nodes are responsible for stitching the IP multicast trees, on
the access side, to the ingress replication tunnels or LSM trees in
the MPLS/IP core. The stitching must ensure that the following
characteristics are maintained at all times:

1. Avoiding Packet Duplication: In the case where the VXLAN network
is multi-homed to multiple PE nodes, if all of the PE nodes forward
the same multicast frame, then packet duplication would arise. This
applies to both multicast traffic from site to core as well as from
core to site.

2. Avoiding Forwarding Loops: In the case of VXLAN network multi-
homing, the solution must ensure that a multicast frame forwarded by
a given PE to the MPLS core is not forwarded back by another PE (in
the same VXLAN network) to the VXLAN network of origin. The same
applies for traffic in the core to site direction.

The following approach of per-VNI load balancing can guarantee proper
stitching that meets the above requirements.

4.6.2. Multicast Stitching with Per-VNI Load Balancing




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To setup multicast trees in the VXLAN network for DC applications,
PIM Bidir can be of special interest because it reduces the amount of
multicast state in the network significantly. Furthermore, it
alleviates any special processing for RPF check since PIM Bidir
doesn't require any RPF check. The RP for PIM Bidir can be any of the
spine nodes. Multiple trees can be built (e.g., one tree rooted per
spine node) for efficient load-balancing within the network. All PEs
participating in the multi-homing of the VXLAN network join all the
trees. Therefore, for a given tree, all PEs receive BUM traffic. DF
election procedures of [EVPN] are used to ensure that only traffic
to/from a single PE is forwarded, thus avoiding packet duplications
and forwarding loops. For load-balancing of BUM traffic, when a PE or
an NVE wants to send BUM traffic over the VXLAN network, it selects
one of the trees based on its VNI and forwards all the traffic for
that VNI on that tree.

Multicast traffic from VXLAN/NVGRE is first subjected to filtering
based on DF election procedures of [EVPN] using the VNI as the
Ethernet Tag. This is similar to filtering in [EVPN] in principal;
however, instead of VLAN ID, VNI is used for filtering, and instead
of being 802.1Q frame, it is a VXLAN encapsulated packet. On the DF
PE, where the multicast traffic is allowed to be forwarded, the VNI
is used to select a bridge domain,. After the packet is de-
capsulated, an L2 lookup is performed based on host MAC DA. It should
be noted that the MAC learning is performed in data-plane for the
traffic received from the VXLAN/NVGRE network and the host MAC SA is
learnt against the source VTEP address.

The PE nodes, connected to a multi-homed VXLAN network, perform BGP
DF election to decide which PE node is responsible for forwarding
multicast traffic associated with a given VNI. A PE would forward
multicast traffic for a given VNI only when it is the DF for this
VNI. This forwarding rule applies in both the site-to-core as well as
core-to-site directions.

4.6.2.1 PIM SM operation

With PIM SM, multicast traffic from the core-to-site could be dropped
since a transit router may decide that the RPF path towards the
anycast address source is toward a PE node that is not the DF.

The PE nodes whether DF or not, has to forward forward multicast
traffic from core-to-side.

The operation would work as follow:

Initially, the PE nodes connected to the multi-homed VXLAN network as
well the VTEPs, join towards the RP for the multicast group for a



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particular VXLAN.

When BUM traffic needs to be flooded from core to site, all the PE
nodes connected to the multi-homed VXLAN network send PIM register
messages to the RP. The multicast flow is identified as (anycast
address, group) in the register message, and the source address for
the PIM-SM register message should be a unique address on the PE node
not the anycast address.

The RP will send a join for the (anycast address, group) upon
receiving the register message, routed towards the closest PE which
could be either the DF or the non-DF. This PE will switch to send
traffic natively. Upon receiving the native traffic, the RP will send
register-stop messages for other PEs that keep sending registering
messages, given that only one PE will get the (anycast address,
group) join.

When VTEPs receive traffic from the RP, VTEPs will send (anycast
address, group) join, routed towards the closet PE to each VTEP. This
starts native forwarding on multiple PE nodes connected to the VXLAN
network, but each VTEP or transit router will only accept multicast
traffic from one of the multi-homed PE nodes.

If PIM state times out when multicast traffic stops for a period of
time, the next flooded packet will trigger the above process again.

It is to be noted that before the RP receives the first natively sent
packet from one particular PE node connected to the multihomed VXLAN
network, all packets encapsulated in the register messages from all
PEs will be forwarded by the RP, causing duplications.

A possible optimization is for all PE nodes connected to the
multihomed VXLAN network to send null-register periodically to
maintain the PIM state at the RP, instead of encapsulating flooded
packets in register messages.

The site-to-core operations for flooding BUM traffic would still be
subject to DF election per VNI as described above.


5. NVGRE

Just like VXLAN, all the above specification would apply for NVGRE,
replacing the VNI with Virtual Subnet Identifier (VSID) and the VTEP
with NVGRE Endpoint.

6. Use Cases Overview




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6.1. Homogeneous Network DCI interconnect Use cases

This covers DCI interconnect of two or more VXLAN based Data center
over MPLS enabled EVPN core.

6.1.1. VNI Base Mode EVPN Service Use Case

This use case handles the EVPN service where there is one to one
mapping between a VNI and an EVI. Ethernet TAG ID of EVPN BGP NLRI
should be set to Zero. BD ID can be derived from the RT associated
with the EVI/VNI.

+---+ +---+
| H1| +---++-------+ +--+ +---------+ +---+ +------+ +---+ | H3|
| M1|--+ ++ +-+PE1+-+ +-+PE3+--+ +--+ +-| M3|
+---+ | || | +--+ |MPLS Core| +---+ | | | | +---+
+---+ |NVE|| VXLAN | | (EVPN) | | VXLAN| |NVE| +---+
| H2| | 1 || | +--+ | | +---+ | | | 2 | | H4|
| M2|--+ +-+ +-+PE2+-+ +-+PE4+--+ +--+ +-| M4|
+---+ +---++-------+ +--+ +---------+ +---+ +------+ +---+ +---+
+--------+------+--------+------+--------+------+--------+--------+
|Original|VXLAN |Original|MPLS |Original|VXLAN |Original|Original|
|Ethernet|Header|Ethernet|Header|Ethernet|Header|Ethernet|Ethernet|
|Frame | |Frame | |Frame | |Frame |Frame |
+--------+------+--------+------+--------+------+--------+--------+
|<----Data Center Site1->|<----EVPN Core>|<---Data Center Site2-->|

Figure 2 VNI Base Service Packet Flow.

VNI base Service(One VNI mapped to one EVI).

Hosts H1, H2, H3 and H4 are hosts and there associated MAC addresses
are M1, M2, M3 and M4. PE1, PE2, PE3 and PE4 are the VXLAN-EVPN
gateways. NVE1 and NVE2 are the originators of the VXLAN based
network.

When host H1 in Data Center Site1 communicates with H3 in Data Center
Site2, H1 forms a layer2 packet with source IP address as IP1 and
Source MAC M1, Destination IP as IP3 and Destination MAC as
M3(assuming that ARP resolution already happened). VNE1 learns Source
MAC and lookup in bridge domain for the Destination MAC. Based on the
MAC lookup, the frame needs to be sent to VXLAN network. VXLAN
encapsulation is added to the original Ethernet frame and frame is
sent over the VXLAN tunnel. Frames arrives at PE1. PE1(i.e. VXLAN
gateway), identifies that frame is a VXLAN frame. The VXLAN header is
de-capsulated and Destination MAC lookup is done in the bridge domain
table of the EVI. Lookup of destination MAC results in the EVPN
unicast NH. This NH will be used for identifying the labels (tunnel



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label and service label) to be added over the EVPN core. Similar
processing is done on the other side of DCI.

6.1.2. VNI Bundle Service Use Case Scenario

In the case of VNI-aware bundle service mode, there are multiple VNIs
are mapped to one EVI. The Ethernet TAG ID must be set to the VNI ID
in the EVPN BGP NLRIs. MPLS label allocation in this use case
scenario can be done either per EVI or per EVI, VNI ID basis. If MPLS
label allocation is done per EVI basis, then in data path there is a
need to push a VLAN TAG for identifying bridge-domain at egress PE so
that Destination MAC address lookup can be done on the bridge domain.

6.1.3. VNI Translation Use Case
+---+ +---+
| H1| +---+ +-------+ +---+ +----------+ +---+ +-------+ +---+ | H3|
| M1|-+ +-+ +-+PE1+-+ +-+PE3+-+ +-+ +-| M3|
+---+ | | | | +---+ |MPLS Core | +---+ | | | | +---+
+---+ |NVE| | VXLAN | | (EVPN) | | VXLAN | |NVE| +---+
| H2| | 1 | | | +---+ | | +---+ | | | 2 | | H4|
| M2|-+ +-+ +-+PE2+-+ +-+PE4+-+ +-+ +-| M4|
+---+ +---+ +-------+ +---+ +----------+ +---+ +-------+ +---+ +---+
|<----VNI ID A--->|<-------EVI-A------->|<----VNI_ID_B--->|
Figure 3 VNI Translation Use Case Scenarios.

There are two or more Data Center sites. These Data Center sites
might use different VNI ID for same service. For example, Service A
usage "VNI_ID_A" at data center site1 and "VNI_ID_B" for same service
in data center site 2. VNI ID A is terminated at ingress EVPN PE and
VNI ID B is encapsulated at the egress EVPN PE.


6.2. Heterogeneous Network DCI Use Cases Scenarios

Data Center sites are upgraded slowly; so heterogeneous network DCI
solution is required from the perspective of migration approach from
traditional data center to VXLAN based data center. For Example Data
Center Site1 is upgrade to VXLAN but Data Center Site 2 and 3 are
still layer2/VLAN based data centers. For these use cases, it is
required to provide VXLAN VLAN interworking over EVPN core.

6.2.1. VXLAN VLAN Interworking Over EVPN Use Case Scenario

The new data center site is VXLAN based data center site. But the
older data center sites are still based on the VLAN.

+---+ +---+
| H1| +---+ +------+ +---+ +---------+ +---+ +-------+ +---+ | H3|



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| M1|-+ +-+ +-+PE1+-+ +-+PE3+-+ +-+ +-| M3|
+---+ | | | | +---+ |MPLS Core| +---+ | | | | +---+
+---+ |NVE| |VXLAN | | (EVPN) | | L2 | |NVE| +---+
| H2| | 1 | | | +---+ | | +---+ |Network| | 2 | | H4|
| M2|-+ +-+ +-+PE2+-+ +-+PE4+-+ +-+ +-| M4|
+---+ +---+ +------+ +---+ +---------+ +---+ +-------+ +---+ +---+
|<--Data Center Site1->|<---EVPN Core--->|<--Data Center Site2-->|
+-----+ +------+-----+ +------+------+-----+ +------+-----+ +-----+
|L2 | |VXLAN |L2 | |MPLS |VLAN |L2 | |VLAN |L2 | |L2 |
|Frame| |Header|Frame| |Header|Header|Frame| |Header|Frame| |Frame|
+-----+ +------+-----+ +------+------+-----+ +------+-----+ +-----+

Figure 5 VXLAN VLAN interworking over EVPN Use Case.

If a service that are represented by VXLAN on one site of data center
and via VLAN at different data center sites, then it is a recommended
to model the service as a VNI base EVPN service. The BGP NLRIs will
always advertise VLAN ID TAG as '0' in BGP routes. The advantage with
this approach is that there is no requirement to do the VNI
normalization at EVPN core. VNI ID A is terminated at ingress EVPN PE
and "VLAN ID B" is encapsulated at the egress EVPN PE.

7. Acknowledgements

The authors would like to acknowledge Wen Lin contributions to this
document.
8. Security Considerations

There are no additional security aspects that need to be discussed
here.
9. IANA Considerations

10. References

10.1 Normative References

[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

10.2 Informative References

[EVPN] Sajassi et al., "BGP MPLS Based Ethernet VPN", RFC 7432,
February, 2012.

[PBB-EVPN] Sajassi et al., "Provider Backbone Bridging Combined with
Ethernet VPN (PBB-EVPN)", RFC 7623, September, 2015.

[VXLAN] Mahalingam, Dutt et al., A Framework for Overlaying



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Virtualized Layer 2 Networks over Layer 3 Networks, RFC 7348, August,
2012.

[NVGRE] Sridharan et al., Network Virtualization using Generic
Routing Encapsulation, RFC 7637, July, 2012.

Authors' Addresses


Sami Boutros
VMware, Inc.
EMail: sboutros@vmware.com

Ali Sajassi
Cisco Systems
EMail: sajassi@cisco.com

Samer Salam
Cisco Systems
EMail: ssalam@cisco.com

Dennis Cai
Cisco Systems
EMail: dcai@cisco.com

Tapraj Singh
Juniper Networks
Email: tsingh@juniper.net

John Drake
Juniper Networks
Email: jdrake@juniper.net

Samir Thoria
Cisco
EMail: sthoria@cisco.com

Jeff Tantsura
Ericsson
Email: jeff.tantsura@ericsson.com











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