RFC 8214

Virtual Private Wire Service Support in Ethernet VPN

📅 published August 2017, from ietf

RFC 8214: Virtual Private Wire Service Support in Ethernet VPN 🦋

Okay bestie, the header is giving 📋✨ This is an IETF doc, and it's on the Standards Track (so it's a real spec people build against 👑). The ISSN is 2070-1721. It was published in August 2017. The authors are S. Boutros (VMware), A. Sajassi (Cisco), S. Salam (Cisco), J. Drake (Juniper Networks), and J. Rabadan (Nokia). The header doesn't list anything this RFC obsoletes or updates 🫶

Abstract ✨

Okay so this doc explains how Ethernet VPN (EVPN) can be used to support the Virtual Private Wire Service (VPWS) in MPLS/IP networks 🌸 EVPN gives VPWS a few big wins: Single-Active and All-Active multihoming (with flow-based load-balancing), no more need for Pseudowire (PW) signaling, and fast protection convergence when a node or link fails. Iconic 💅

Status of This Memo

This is an Internet Standards Track document 🎀

It's a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community, got public review, and was approved for publication by the Internet Engineering Steering Group (IESG). If you want more on Internet Standards, check Section 2 of RFC 7841 🧚

For the current status, any errata, and how to send feedback, go to https://www.rfc-editor.org/info/rfc8214 🌈

Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved 💜

This doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) as they were on the publication date. Read those carefully, because they spell out your rights and restrictions. Code Components pulled out of this document must include the Simplified BSD License text (see Section 4.e of the Trust Legal Provisions), and they come with no warranty, as described in the Simplified BSD License ⚖️

Table of Contents

   1. Introduction ....................................................3
      1.1. Terminology ................................................5
   2. Service Interface ...............................................6
      2.1. VLAN-Based Service Interface ...............................6
      2.2. VLAN Bundle Service Interface ..............................7
           2.2.1. Port-Based Service Interface ........................7
      2.3. VLAN-Aware Bundle Service Interface ........................7
   3. BGP Extensions ..................................................7
      3.1. EVPN Layer 2 Attributes Extended Community .................8
   4. Operation ......................................................10
   5. EVPN Comparison to PW Signaling ................................11
   6. Failure Scenarios ..............................................12
      6.1. Single-Homed CEs ..........................................12
      6.2. Multihomed CEs ............................................12
   7. Security Considerations ........................................13
   8. IANA Considerations ............................................13
   9. References .....................................................13
      9.1. Normative References ......................................13
      9.2. Informative References ....................................14
   Acknowledgements ..................................................16
   Contributors ......................................................16
   Authors' Addresses ................................................17

1. Introduction 🌸

Okay so, this doc is all about how EVPN can be used to support VPWS in MPLS/IP networks 💖 Using EVPN for VPWS (we call it EVPN-VPWS) brings all the EVPN perks to Point-to-Point (P2P) services. That means Single-Active redundancy and All-Active redundancy with flow-based load-balancing ✨ It also means you don't need the traditional PW signaling for P2P Ethernet services anymore. More on that in Section 4 🦋

Now the background 🧠 [RFC7432] lets you forward customer traffic to and from a given customer Attachment Circuit (AC) with no Media Access Control (MAC) lookup at all. That's perfect for P2P services (aka VPWS services) 🎀 [MEF] defines the Ethernet Virtual Private Line (EVPL) service as a P2P service between a pair of ACs (picked out by VLANs). It also defines the Ethernet Private Line (EPL) service, where every traffic flow goes between one single pair of ports. In EVPN terms, that would mean one single pair of Ethernet Segments ES(es). An EVPL can be thought of as a VPWS with only two ACs 🫶

When it comes to delivering an EVPL, EVPN's forwarding works by swapping a pair of Ethernet Auto-Discovery (A-D) routes. For the more general VPWS from [RFC4664], EVPN forwarding instead uses a group of Ethernet A-D routes, one per AC/ES. So in a VPWS service, traffic leaving one originating Ethernet Segment can only ever go to one destination Ethernet Segment. That means no MAC lookup is needed, and the MPLS label tied to the per-EVPN instance (EVI) Ethernet A-D route can be used to forward user traffic to the destination AC 🌈

A specific VPWS service instance is identified by a pair of per-EVI Ethernet A-D routes. Together, those routes identify the VPWS service instance endpoints and the instance itself, for both EPL and EVPL services 💅 In the control plane, each Provider Edge (PE) node advertises its own VPWS service instance identifiers, and that's how the instance gets identified. In the data plane, the MPLS label one PE advertises is what the other PE uses to send traffic for that instance 🧚 Just like the Ethernet Tag in standard EVPN, the VPWS service instance identifier is unique within an EVPN instance ✨

Here's the Ethernet Tag ID drama 👀 For EVPN routes, Ethernet Tag IDs are set to zero for port-based, VLAN-based, and VLAN bundle interface modes. They're set to non-zero Ethernet Tag IDs for VLAN-aware bundle mode. For EVPN-VPWS, though, the Ethernet Tag ID in the Ethernet A-D route MUST be set to a non-zero value for all four service interface types. Strict, but iconic 💀

Now, route advertisement and MPLS label lookup 🔥 EVPN-VPWS kinda resembles the VLAN-aware bundle mode from [RFC7432]. When a PE advertises a per-EVI Ethernet A-D route, the VPWS service instance acts as a 32-bit normalized Ethernet Tag ID. The MPLS label in that route represents both the EVI and the VPWS service instance. So when an MPLS-encapsulated packet arrives, the disposition PE can figure out the egress AC from the label, then do any tag translation that's needed 💖 For the EVPL service, Ethernet frames carried over the MPLS/IP network SHOULD stay tagged with the originating VLAN ID (VID), and any VID translation MUST be done at the disposition PE. For the EPL service, the Ethernet frames are carried as-is, and the tags are not touched 🎀

The MPLS label value in the Ethernet A-D route can be set to the Virtual Extensible LAN (VXLAN) Network Identifier (VNI) for VXLAN encapsulation, as per [RFC7348] 🦋 That VNI has a local scope per PE, and it may also be equal to the VPWS service instance identifier set in the Ethernet A-D route. When you use VXLAN encapsulation, the BGP Encapsulation extended community goes in the Ethernet A-D route, as described in [EVPN-OVERLAY] 🌸 The VNI works like the MPLS label, in that it's set in the tunnel header used to tunnel Ethernet packets from all the service interface types defined in Section 2. The EVPN-VPWS techniques in this document don't depend on the tunneling technology at all, so you're free to pick 💜

The Ethernet Segment Identifier in the Ethernet A-D per-EVI route isn't used to identify the service. It can still be used for flow-based load-balancing and mass withdraw functions, following the [RFC7432] baseline 🧚

Same as standard EVPN, the Ethernet A-D per-ES route is what gives you fast convergence when a link or node fails ⚡ The Ethernet Segment route handles auto-discovery of the PEs attached to a given multihomed Customer Edge node (CE), and it syncs state between them 🫶

1.1. Terminology 📚

Here's the key-word rule 🔑 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 read as described in BCP 14 [RFC2119] [RFC8174], but only when they show up in all capitals, exactly like that. Lowercase versions are just regular words 💅

Now the glossary, bestie 🎀

  • EVPN: Ethernet VPN.
  • MAC: Media Access Control.
  • MPLS: Multiprotocol Label Switching.
  • OAM: Operations, Administration, and Maintenance.
  • PE: Provider Edge Node.
  • AS: Autonomous System.
  • ASBR: Autonomous System Border Router.
  • CE: Customer Edge device (e.g., host, router, or switch).
  • EVPL: Ethernet Virtual Private Line.
  • EPL: Ethernet Private Line.
  • EP-LAN: Ethernet Private LAN.
  • EVP-LAN: Ethernet Virtual Private LAN.
  • S-VLAN: Service VLAN identifier.
  • C-VLAN: Customer VLAN identifier.
  • VID: VLAN ID.
  • VPWS: Virtual Private Wire Service.
  • EVI: EVPN Instance.
  • P2P: Point to Point.
  • VXLAN: Virtual Extensible LAN.
  • DF: Designated Forwarder.
  • L2: Layer 2.
  • MTU: Maximum Transmission Unit.
  • eBGP: External Border Gateway Protocol.
  • iBGP: Internal Border Gateway Protocol.
  • ES: "Ethernet Segment" on a PE refers to the link attached to it 🔗 This link can be part of a set of links attached to different PEs in multihomed cases, or it can be a single link in single-homed cases.
  • ESI: Ethernet Segment Identifier.
  • Single-Active Mode: When a device or network is multihomed to two or more PEs, and only a single PE in that redundancy group can forward traffic to and from the multihomed device or network for a given VLAN, the multihoming or redundancy is called "Single-Active" 👑
  • All-Active Mode: When a device is multihomed to two or more PEs, and all the PEs in that redundancy group can forward traffic to and from the multihomed device for a given VLAN, the multihoming or redundancy is called "All-Active" 🌈
  • VPWS Service Instance: A VPWS service instance is represented by a pair of EVPN service labels associated with a pair of endpoints 🦋 Each label is downstream-assigned and advertised by the disposition PE through an Ethernet A-D per-EVI route. The downstream label identifies the endpoint on the disposition PE. A VPWS service instance can be associated with only one VPWS service identifier 💜

2. Service Interface ✨

To be continued in part 2 🎀

2.1. VLAN-Based Service Interface 🎀

Okay bestie, with this one a VPWS instance identifier lines up with just ONE VLAN on one specific interface 🦋 So it's a one-to-one mapping between a VID on that interface and the VPWS service instance identifier. The PE handles the cross-connect between an MPLS Label Switched Path (LSP) identified by the VPWS service instance identifier and a specific <port, VLAN>. 💅

Now here's where it gets spicy 🌶️ If the VLAN is represented by different VIDs on different PEs and different ES(es) (for example, a different VID per Ethernet Segment per PE), then each PE needs to perform VID translation for frames destined to its Ethernet Segment. In those scenarios, the Ethernet frames transported over an MPLS/IP network SHOULD remain tagged with the originating VID, and a VID translation MUST be supported in the data path and MUST be performed on the disposition PE. 🧚

2.2. VLAN Bundle Service Interface ✨

With this one, a VPWS service instance identifier corresponds to multiple VLANs on a specific interface 🌈 The PE does the cross-connect between the MPLS label identified by the VPWS service instance identifier and a group of VLANs on that interface. Each VLAN is presented by a single VID, which means no VLAN translation is allowed. 🙅‍♀️

The receiving PE can direct the traffic to a specific port based on the EVPN label alone 🫶 And the transmitting PE can cross-connect traffic from a group of VLANs on a specific port to the MPLS label. The MPLS-encapsulated frames MUST remain tagged with the originating VID. 💜

2.2.1. Port-Based Service Interface 🍓

This one is a special case of the VLAN bundle service interface, where all of the VLANs on the port are mapped to the same VPWS service instance identifier. The procedures are identical to those described in Section 2.2. Same vibes, just a bigger bundle 😭

2.3. VLAN-Aware Bundle Service Interface 🦋

Contrary to EVPN, in EVPN-VPWS this service interface maps to a VLAN-based service interface (defined in Section 2.1), so this service interface is not used in EVPN-VPWS. In other words, if you tried to define data-plane and control-plane behavior for it, you'd realize it's the same as the VLAN-based service. It's giving déjà vu 🌸

3. BGP Extensions 💖

This document specifies the use of the per-EVI Ethernet A-D route to signal VPWS services. The ESI field is set to the customer ES, and the 32-bit Ethernet Tag ID field MUST be set to the VPWS service instance identifier value. The VPWS service instance identifier value MAY be set to a 24-bit value, and when a 24-bit value is used, it MUST be right-aligned. 🎀

For both EPL and EVPL services using a given VPWS service instance, the pair of PEs instantiating that VPWS service instance will each advertise a per-EVI Ethernet A-D route with its VPWS service instance identifier, and each will be configured with the other PE's VPWS service instance identifier. Once each PE has received the other PE's per-EVI Ethernet A-D route, the VPWS service instance is instantiated. It should be noted that the same VPWS service instance identifier may be configured on both PEs. 👑

The Route Target (RT) extended community the per-EVI Ethernet A-D route is tagged with identifies the EVPN instance the VPWS service instance is configured in. It's the operator's choice how many VPWS service instances are configured in a given EVPN instance, and which ones. However, a given EVPN instance MUST NOT be configured with both VPWS service instances and standard EVPN multipoint services. No mixing, bestie 🙅‍♀️💅

3.1. EVPN Layer 2 Attributes Extended Community 🧚

This document defines a new extended community [RFC4360], to be included with per-EVI Ethernet A-D routes. This attribute is mandatory if multihoming is enabled. ⭐

           +-------------------------------------------+
           |  Type (0x06) / Sub-type (0x04) (2 octets) |
           +-------------------------------------------+
           |  Control Flags  (2 octets)                |
           +-------------------------------------------+
           |  L2 MTU (2 octets)                        |
           +-------------------------------------------+
           |  Reserved (2 octets)                      |
           +-------------------------------------------+

Figure 1: EVPN Layer 2 Attributes Extended Community

        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   MBZ                   |C|P|B|  (MBZ = MUST Be Zero)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 2: EVPN Layer 2 Attributes Control Flags

The following bits in Control Flags are defined. The remaining bits MUST be set to zero when sending and MUST be ignored when receiving this community. 🫶

Name     Meaning
---------------------------------------------------------------
P        If set to 1 in multihoming Single-Active scenarios,
         this flag indicates that the advertising PE is the
         primary PE.  MUST be set to 1 for multihoming
         All-Active scenarios by all active PE(s).

B        If set to 1 in multihoming Single-Active scenarios,
         this flag indicates that the advertising PE is the
         backup PE.

C        If set to 1, a control word [RFC4448] MUST be present
         when sending EVPN packets to this PE.  It is
         recommended that the control word be included in the
         absence of an entropy label [RFC6790].

L2 MTU is a 2-octet value indicating the MTU in bytes. 📏

A received L2 MTU of zero means that no MTU checking against the local MTU is needed. A received non-zero MTU MUST be checked against the local MTU, and if there is a mismatch, the local PE MUST NOT add the remote PE as the EVPN destination for the corresponding VPWS service instance. Mismatch = no entry, periodt 🙅‍♀️🔥

The usage of the per-ES Ethernet A-D route is unchanged from its usage in [RFC7432]. That means the "Single-Active" bit in the flags of the ESI Label extended community will indicate whether Single-Active or All-Active redundancy is used for this ES. 🦋

In a multihoming All-Active scenario, there is no Designated Forwarder (DF) election. All the PEs in the ES that are active and ready to forward traffic to or from the CE will set the P Flag. A remote PE will do per-flow load-balancing to the PEs that set the P Flag for the same Ethernet Tag and ESI. The B Flag in Control Flags SHOULD NOT be set in the multihoming All-Active scenario, and MUST be ignored by receiving PE(s) if it is set. 🌸

In a multihoming Single-Active scenario for a given VPWS service instance, the DF election should result in the primary-elected PE for the VPWS service instance advertising the P Flag set and the B Flag clear. The backup-elected PE should advertise the P Flag clear and the B Flag set, and the rest of the PEs in the same ES should signal both the P Flag and the B Flag clear. 🎀

When the primary PE/ES fails, the primary PE will withdraw the associated Ethernet A-D routes for the VPWS service instance from the remote PE, and the remote PE should then send traffic associated with the VPWS instance to the backup PE. 😭 DF re-election will happen between the PE(s) in the same ES, and there will be a newly elected primary PE and a newly elected backup PE that will signal the P and B Flags as described above. Plot twist, but it's all covered ✨

A remote PE SHOULD receive the P Flag set from only one primary PE and the B Flag set from only one backup PE. However, during transient situations, a remote PE receiving a P Flag set from more than one PE will select the last advertising PE as the primary PE when forwarding traffic. A remote PE receiving a B Flag set from more than one PE will select the last advertising PE as the backup PE. 🦋

A remote PE MUST receive a P Flag set from at least one PE before forwarding traffic. No P Flag, no forwarding, no cap 🧢

If a network uses entropy labels per [RFC6790], then the C Flag MUST NOT be set, and the control word MUST NOT be used when sending EVPN-encapsulated packets over a P2P LSP. 💀🌈

4. Operation ✨

Okay bestie, let's look at a P2P service deployed with EVPN 💖 Here's the vibe:

      Ethernet                                          Ethernet
      Native   |<--------- EVPN Instance ----------->|  Native
      Service  |                                     |  Service
      (AC)     |     |<-PSN1->|       |<-PSN2->|     |  (AC)
         |     V     V        V       V        V     V  |
         |     +-----+      +-----+  +-----+   +-----+  |
  +----+ |     | PE1 |======|ASBR1|==|ASBR2|===| PE3 |  |    +----+
  |    |-------+-----+      +-----+  +-----+   +-----+-------|    |
  | CE1| |                                              |    |CE2 |
  |    |-------+-----+      +-----+  +-----+   +-----+-------|    |
  +----+ |     | PE2 |======|ASBR3|==|ASBR4|===| PE4 |  |    +----+
       ^       +-----+      +-----+  +-----+   +-----+          ^
       |   Provider Edge 1        ^        Provider Edge 2      |
       |                          |                             |
       |                          |                             |
       |              EVPN Inter-provider point                 |
       |                                                        |
       |<---------------- Emulated Service -------------------->|

               Figure 3: EVPN-VPWS Deployment Model

okay so iBGP sessions get set up between PE1, PE2, ASBR1, and ASBR3, possibly through a BGP route reflector 🧚. Same energy for PE3, PE4, ASBR2, and ASBR4, which also get iBGP sessions 🫶. Then eBGP sessions are set up among ASBR1, ASBR2, ASBR3, and ASBR4 🌈.

All the PEs and ASBRs are enabled for the EVPN Subsequent Address Family Identifier (SAFI) 💅 and they exchange per-EVI Ethernet A-D routes, one route per VPWS service instance. For inter-AS option B, the ASBRs re-advertise these routes with the NEXT_HOP attribute set to their IP addresses as per [RFC4271] 🎀.

The link between the CE and the PE is either a C-tagged or S-tagged interface, as described in [802.1Q] ✨. It can carry a single VLAN tag or two nested VLAN tags, and it's configured as a trunk with multiple VLANs, one per VPWS service instance. It should be noted that the VLAN ID the customer uses at either end of a VPWS service instance to identify that service instance may be different, and EVPN doesn't do that translation between the two values 🙈. Instead, the MPLS label is what identifies the VPWS service instance, and if translation is needed, it should be done by the Ethernet interface for each service 🦋.

For a single-homed CE, in an advertised per-EVI Ethernet A-D route, the ESI field is set to zero and the Ethernet Tag ID is set to the VPWS service instance identifier that identifies the EVPL or EPL service 💖.

For a multihomed CE, in an advertised per-EVI Ethernet A-D route, the ESI field is set to the CE's ESI and the Ethernet Tag ID is set to the VPWS service instance identifier. That identifier MUST have the same value on all PEs attached to that ES 👑. This lets an ingress PE in a multihoming All-Active scenario do flow-based load-balancing of traffic flows to all of the PEs attached to that ES 💅. In all cases, traffic follows the transport paths, which may be asymmetric 🌸.

Either (1) the VPWS service instance identifier encoded in the Ethernet Tag ID in an advertised per-EVI Ethernet A-D route MUST be unique across all ASes, or (2) an ASBR needs to perform a translation when the per-EVI Ethernet A-D route gets re-advertised by the ASBR from one AS to the other AS 🫣.

A per-ES Ethernet A-D route can be used for mass withdraw, to withdraw all per-EVI Ethernet A-D routes associated with the multihomed site on a given PE 🧹.

5. EVPN Comparison to PW Signaling

Okay, comparison time 🦋. In EVPN, service endpoint discovery and label signaling happen at the same time using BGP ✨. With VPWS based on [RFC4448], label signaling is done via LDP, and service endpoint discovery is either manual provisioning or BGP 🧚.

In existing VPWS implementations using PWs, redundancy is limited to Single-Active mode 🙃. With EVPN implementations of VPWS, both Single-Active and All-Active redundancy modes can be supported, which is giving options 💖.

In existing implementations with PWs, backup PWs aren't used to carry traffic 😭. With EVPN, traffic can be load-balanced among different PEs multihomed to a single CE 🌈.

When a link or node fails, EVPN can trigger failover with the withdrawal of a single BGP route per EVPL service or multiple EVPL services 🔥. With VPWS PW redundancy, the failover sequence needs two control-plane messages: one to deactivate the group of primary PWs, and a second to activate the group of backup PWs associated with the access link 💀.

Finally, EVPN may employ data-plane egress link protection mechanisms that VPWS doesn't have 🍓. This can be done by the primary PE (on local AC down) using the label advertised in the per-EVI Ethernet A-D route by the backup PE, to encapsulate the traffic and direct it to the backup PE 🎀.

6. Failure Scenarios

Now the scary part, but make it cute 🥺. On a link or port failure between the CE and the PE, for both single-homed and multihomed CEs, unlike [RFC7432], the PE MUST withdraw all the associated Ethernet A-D routes for the VPWS service instances on the failed port or link 💔.

6.1. Single-Homed CEs

Unlike [RFC7432], EVPN-VPWS uses Ethernet A-D route advertisements for single-homed Ethernet Segments 🧩. So if a link or port fails on a given single-homed Ethernet Segment, the PE MUST withdraw the associated per-EVI Ethernet A-D routes 🚨.

6.2. Multihomed CEs

For faster convergence in multihomed scenarios, with either Single-Active redundancy or All-Active redundancy, a mass withdraw technique is used 🏃‍♀️💨. A PE that was previously advertising a per-ES Ethernet A-D route can withdraw that route by signaling to the remote PEs to switch all the VPWS service instances associated with this multihomed ES to the backup PE 🦸‍♀️.

Just like RFC 7432, the Ethernet A-D per-EVI route MUST NOT be used for traffic forwarding by a remote PE until it also receives the associated set of Ethernet A-D per-ES routes 🛑.

7. Security Considerations

Serious moment, bestie 🔒. The mechanisms in this document use the EVPN control plane as defined in [RFC7432]. The security considerations described in [RFC7432] are equally applicable 🛡️.

This document uses MPLS and IP-based tunnel technologies to support data-plane transport. The security considerations described in [RFC7432] and in [EVPN-OVERLAY] are equally applicable too 🙏.

8. IANA Considerations

IANA has allocated the following EVPN Extended Community sub-type 🎉:

   Sub-Type Value     Name                        Reference
   --------------------------------------------------------
   0x04               EVPN Layer 2 Attributes     RFC 8214

This document creates a registry called "EVPN Layer 2 Attributes Control Flags" 📋. New registrations will be made through the "RFC Required" procedure defined in [RFC8126] ✨.

Initial registrations are as follows 💅:

     P      Advertising PE is the primary PE.
     B      Advertising PE is the backup PE.
     C      Control word [RFC4448] MUST be present.

9. References

9.1. Normative References

[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>.

[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>.

[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>.

[RFC4448]  Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron,
           "Encapsulation Methods for Transport of Ethernet over MPLS
           Networks", RFC 4448, DOI 10.17487/RFC4448, April 2006,
           <https://www.rfc-editor.org/info/rfc4448>.

[RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
           L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
           RFC 6790, DOI 10.17487/RFC6790, November 2012,
           <https://www.rfc-editor.org/info/rfc6790>.

[RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
           Border Gateway Protocol 4 (BGP-4)", RFC 4271,
           DOI 10.17487/RFC4271, January 2006,
           <https://www.rfc-editor.org/info/rfc4271>.

[RFC4360]  Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
           Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
           February 2006, <https://www.rfc-editor.org/info/rfc4360>.

[RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
           Writing an IANA Considerations Section in RFCs", BCP 26,
           RFC 8126, DOI 10.17487/RFC8126, June 2017,
           <https://www.rfc-editor.org/info/rfc8126>.

[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>.

9.2. Informative References

[MEF]      Metro Ethernet Forum, "EVC Ethernet Services Definitions
           Phase 3", Technical Specification MEF 6.2, August 2014,
           <https://www.mef.net/Assets/Technical_Specifications/
           PDF/MEF_6.2.pdf>.

[RFC4664]  Andersson, L., Ed., and E. Rosen, Ed., "Framework for
           Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664,
           DOI 10.17487/RFC4664, September 2006,
           <https://www.rfc-editor.org/info/rfc4664>.

[EVPN-OVERLAY]
           Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R.,
           Uttaro, J., and W. Henderickx, "A Network Virtualization
           Overlay Solution using EVPN", Work in Progress,
           draft-ietf-bess-evpn-overlay-08, March 2017.

[802.1Q]   IEEE, "IEEE Standard for Local and metropolitan area
           networks -- Media Access Control (MAC) Bridges and Virtual
           Bridge Local Area Networks", IEEE Std 802.1Q-2011,
           DOI 10.1109/IEEESTD.2011.6009146.

Acknowledgements

The authors would like to give a huge shoutout to Jeffrey Zhang, Wen Lin, Nitin Singh, Senthil Sathappan, Vinod Prabhu, Himanshu Shah, Iftekhar Hussain, Alvaro Retana, and Acee Lindem for their feedback and contributions to this document 🫶💜.

Contributors

In addition to the authors listed on the front page, these coauthors also contributed to this document 🌟:

Jeff Tantsura
Individual
Email: jefftant@gmail.com

Dirk Steinberg
Steinberg Consulting
Email: dws@steinbergnet.net

Patrice Brissette
Cisco Systems
Email: pbrisset@cisco.com

Thomas Beckhaus
Deutsche Telecom
Email: Thomas.Beckhaus@telekom.de

Ryan Bickhart
Juniper Networks
Email: rbickhart@juniper.net

Daniel Voyer
Bell Canada

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


John Drake
Juniper Networks

Email: jdrake@juniper.net


Jorge Rabadan
Nokia

Email: jorge.rabadan@nokia.com
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