Internet DRAFT - draft-eastlake-bess-evpn-vxlan-bypass-vtep

draft-eastlake-bess-evpn-vxlan-bypass-vtep







BESS Working Group                                           D. Eastlake
Internet-Draft                                    Futurewei Technologies
Intended status: Standards Track                                   Z. Li
Expires: 25 May 2024                                           S. Zhuang
                                                     Huawei Technologies
                                                                R. White
                                                        Juniper Networks
                                                        22 November 2023


                         EVPN VXLAN Bypass VTEP
             draft-eastlake-bess-evpn-vxlan-bypass-vtep-13

Abstract

   A principal feature of EVPN is the ability to support multihoming
   from a customer equipment (CE) to multiple provider edge equipment
   (PE) with all-active links.  This draft specifies a mechanism to
   simplify PEs used with VXLAN tunnels and enhance VXLAN Active-Active
   reliability.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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   This Internet-Draft will expire on 25 May 2024.

Copyright Notice

   Copyright (c) 2023 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
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   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components



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   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology and Acronyms" . . . . . . . . . . . . . . . .   2
   2.  VXLAN Gateway High Reliability  . . . . . . . . . . . . . . .   3
   3.  Detailed Problem and Solution Requirement . . . . . . . . . .   5
   4.  The Bypass VXLAN Extended Community Attribute . . . . . . . .   6
   5.  Control Plane Processing  . . . . . . . . . . . . . . . . . .   7
   6.  Data Packet Processing  . . . . . . . . . . . . . . . . . . .   7
     6.1.  Layer 2 Unicast Packet Forwarding . . . . . . . . . . . .   8
       6.1.1.  Uplink  . . . . . . . . . . . . . . . . . . . . . . .   8
       6.1.2.  Downlink  . . . . . . . . . . . . . . . . . . . . . .   8
     6.2.  BUM Packet Forwarding . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  IPv4 Specific . . . . . . . . . . . . . . . . . . . . . .   9
     7.2.  IPv6 Specific . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   10. Informative References  . . . . . . . . . . . . . . . . . . .  10
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  10
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   A principal feature of EVPN is the ability to support multihoming
   from a customer equipment (CE) to multiple provider edge equipment
   (PE) with links used in the all-active redundancy mode.  That mode is
   where a device is multihomed to a group of two or more PEs and where
   all PEs in such a redundancy group can forward traffic to/from the
   multihomed device or network for a given VLAN [RFC7209].  This draft
   specifies a VXLAN gateway mechanism to simplify PE processing in the
   multi-homed case and enhance VXLAN Active-Active reliability.

1.1.  Terminology and Acronyms"

   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.

   This document uses the following acronyms and terms:




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   All-Active Redundancy Mode  - When a device is multihomed to a group
      of two or more PEs and when all PEs in such redundancy group can
      forward traffic to/from the multihomed device or network for a
      given VLAN.

   BUM  - Broadcast, Unknown unicast, and Multicast.

   CE  - Customer Edge equipment.

   DCI  - Data Center Interconnect.

   ESI  - Ethernet Segment Identifier - A unique non-zero identifier
      that identifies an Ethernet segment.

   NVE  - Network Virtualization Edge.

   PE  - Provider Edge equipment.

   Single-Active Redundancy Mode  - When a device or a network is
      multihomed to a group of two or more PEs and when only a single PE
      in such a redundancy group can forward traffic to/from the
      multihomed device or network for a given VLAN.

   VTEP  - VXLAN Tunnel End Point.

   VXLAN  - Virtual eXtensible Local Area Network [RFC7348].

2.  VXLAN Gateway High Reliability

   One example of the current situation would be a DCI (data center
   interconnect) using VXLAN tunnels that is multihomed for reliability
   as show in Figure 1.  Each PE as a VXLAN Tunnel End Point (VTEP) uses
   a different IP adress.  Thus each PE must process EVPN updates based
   on the ESIs [RFC7432].

















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                                 .........
                                 .  DCI  .
               +----------+      .       .      +----------+
               | PE       +---------------------+ PE       |
               |VTEP IP-1 +---   . VXLAN .   ---+VTEP IP-3 |
               +----------+   \  .Tunnels.  /   +----------=
              /     |          -----   -----          |     \
          +--+      |            .  \ /  .            |      +--+
          |CE|      |            .   X   .            |      |CE|
          +--+      |            .  / \  .            |      +--+
              \     |          -----   -----          |    /
               +----------+   /  . VXLAN .  \   +----------+
               | PE       +---   .Tunnels.   ---+ PE       |
               |VTEP IP-2 +---------------------+VTEP IP-4 |
               +----------+      .       .      +----------+
                                 .........

                        Figure 1: Current Situation

   The situation is greatly simplified if the set of VTEPs connected to
   a particular Ethernet segment all use the same anycast IP address.
   PEs no longer need to conern themselves with whether a remote CE is
   single or multi-homed.  The situation is as shown in Figure 2.  The
   IP address within each VTEP group is synchronized by messages within
   that group.

                                 .........
                                 .  DCI  .
               +----------+      .       .      +----------+
               | Anycast  |      .       .      | Anycast  |
               |VTEP IP-1 +---   .       .   ---+VTEP IP-2 |
               +----------+   \  .       .  /   +----------=
              /     ^          \ .       . /          ^     \
          +--+      |           \.       ./           |      +--+
          |CE|    Sy|nc          >-------<          Sy|nc    |CE|
          +--+      |           /. VXLAN .\           |      +--+
              \     v          / . Tunnel. \          v    /
               +----------+   /  .       .  \   +----------+
               | Anycast  +---   .       .   ---+ Anycast  |
               |VTEP IP-1 |      .       .      |VTEP IP-2 |
               +----------+      .       .      +----------+
                                 .........

                     Figure 2: Situation Using Anycast







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3.  Detailed Problem and Solution Requirement

   In the scenario illustrated in Figure 3, where an enterprise site and
   a data center are interconnected, the VPN gateways (PE1 and PE2) and
   the enterprise site (CPE) are connected through a VXLAN tunnel to
   provide L2/L3 services between the enterprise site (CPE) and data
   center.  The data center gateway (CE1) is dual-homed to PE1 and PE2
   to access the VXLAN network, which enhances network access
   reliability.  When one PE fails, services can be rapidly switched to
   the other PE, minimizing the impact on services.

   As shown in Figure 3, PE1 and PE2 use a virtual address as a Network
   Virtualization Edge (NVE) interface address at the network side,
   namely, the Anycast VTEP address.  In this way, the CPE is aware of
   only one remote NVE interface and establishes a VXLAN tunnel with the
   virtual address.  The packets from the CPE can reach CE1 through
   either PE1 or PE2.  However, single-homed CEs may exist, such as CE2
   and CE3.  As a result, after reaching a PE, the packets from the CPE
   may need to be forwarded by the other PE to a single-homed CE.
   Therefore, a bypass VXLAN tunnel needs to be established between PE1
   and PE2.  An EVPN peer relationship is established between PE1 and
   PE2.  Different addresses, namely, bypass VTEP addresses, are
   configured for PE1 and PE2 so that they can establish a bypass VXLAN
   tunnel.

                                      +-----+
                     ---------------- | CPE |   Enterprise site
                        ^             +-----+
                        |               / \
                        |              /   \
                      VXLAN Tunnel    /     \
                        |            /       \
                        |           / Anycast \
                        v      +-----+ VTEP +-----+
                     --------- | PE1 |------| PE2 |
                               +-----+      +-----+
                                 /\           /\
                                /  \         /  \
                               /    \ Trunk /    \
                              /      \     /      \
                             /       +\---/+       \
                            /        | \ / |        \
                           /         +--+--+         \
                          /             |             \
                      +-----+        +-----+        +-----+
                      | CE2 |        | CE1 |        | CE3 |
                      +-----+        +-----+        +-----+




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       Figure 3: Basic networking of the VXLAN active-active scenario

4.  The Bypass VXLAN Extended Community Attribute

   This sections specifies the extensions to meet the requirements given
   in Section 3 and enhance VXLAN active-active reliability.

   This document specifies two new BGP extended communities, the IPv4
   and IPv6 Bypass VXLAN Extended Communities.  These extended
   communities are IPv4-address-specific or IPv6-address-specific,
   depending on whether the VTEP address to be accommodated is IPv4 or
   IPv6.  In the new extended communities, the 4-byte or 16-byte global
   administrator field encodes the IPv4 or IPv6 address that is the VTEP
   address and the 2-byte local administrator field is formatted as
   shown in Figures 4 and 5.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Type=0x01    | Sub-Type=TBA1 |         IPv4 Address          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |      IPv4 Address (cont.)     |    Flags      |   Reserved    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 4: IPv4-address-specific Bypass VXLAN Extended Community


      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Type=0x00/0x40| Sub-Type=TBA2 |    Target IPv6 Address        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |           Target IPv6 Address (cont.)                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |           Target IPv6 Address (cont.)                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |           Target IPv6 Address (cont.)                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Target IPv6 Address (cont.)  |    Flags      |   Reserved    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 5: IPv6-address-specific Bypass VXLAN Extended Community

   Where

   Type:  0x01 = type for transitive IPv4 specific use.

      0x00 = type for transitive IPv6 specific use.



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      0x40 = type for non-transitive IPv6 specific use.

   Sub-Type:  TBA1 = subtype for IPv4 specific use.

      TBA2 = subtype for IPv6 specific use.

   IPv4/IPv6:  An address of that type.

   Flags:  MUST be sent as zero and ignored on receipt.

   Reserved:  MUST be sent as zero and ignored on receipt.

5.  Control Plane Processing

   Using the topology in Figure 3:

   1.  PE2 sends a multicast route to PE1.  The source address of the
       route is the Anycast VTEP address shared by PE1 and PE2.  The
       route carries the bypass VXLAN extended community attribute,
       including the bypass VTEP address of PE1.

   2.  After receiving the multicast route from PE2, PE1 considers that
       an Anycast relationship be established with PE2.  This is because
       the source address (Anycast VTEP address) of the route is the
       same as the local virtual address of PE1 and the route carries
       the bypass VTEP extended community attribute.  Based on the
       bypass VXLAN extended attribute of the route, PE1 establishes a
       bypass VXLAN tunnel to PE2.

   3.  PE1 learns the MAC address of the CEs through upstream packets
       from the CEs and advertises them as routes to PE2 through BGP
       EVPN.  The routes carry the ESI of the links accessed by the CEs,
       and information about the VLANs that the CE access, and the
       bypass VXLAN extended community attribute.

   4.  PE1 learns the MAC address of the CPE through downstream packets
       at the network side, specifies that the next-hop address of the
       MAC route can be iterated to a static VXLAN tunnel, and
       advertises the route to PE2.  The next-hop address of the MAC
       route cannot be changed.

6.  Data Packet Processing

   This section describes how Layer 2 unicast and BUM (Broadcast,
   Unknown unicast, and Multicast) packets are forwarded.  A description
   of how Layer 3 packets transmitted on the same subnet and Layer 3
   packets transmitted across subnets cases are forwarded will be
   provided in a furture version of this document.



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6.1.  Layer 2 Unicast Packet Forwarding

   The following two subsections discuss Layer 2 unicast forwarding in
   the topology shown in Figure 3.

6.1.1.  Uplink

   After receiving Layer 2 unicast packets destined for the CPE from
   CE1, CE2, and CE3, PE1 and PE2 search for their local MAC address
   table to obtain outbound interfaces, perform VXLAN encapsulation on
   the packets, and forward them to the CPE.

6.1.2.  Downlink

   After receiving a Layer 2 unicast packet sent by the CPE to CE1, PE1
   performs VXLAN decapsulation on the packet, searches the local MAC
   address table for the destination MAC address, obtains the outbound
   interface, and forwards the packet to CE1.

   After receiving a Layer 2 unicast packet sent by the CPE to CE2, PE1
   performs VXLAN decapsulation on the packet, searches the local MAC
   address table for the destination MAC address, obtains the outbound
   interface, and forwards the packet to CE2.

   After receiving a Layer 2 unicast packet sent by the CPE to CE3, PE1
   performs VXLAN decapsulation on the packet, searches the local MAC
   address table for the destination MAC address, and forwards it to PE2
   over the bypass VXLAN tunnel.  After the packet reaches PE2, PE2
   searches the destination MAC address, obtains the outbound interface,
   and forwards the packet to CE3.

   The process for PE2 to forward packets from the CPE is the same as
   that for PE1 to forward packets from the CPE with the roles of CE2
   and CE3 swapped.

6.2.  BUM Packet Forwarding

   Using the topology in Figure 3, if the destination address of a BUM
   packet from the CPE is the Anycast VTEP address of PE1 and PE2, the
   BUM packet may be forwarded to either PE1 or PE2.  If the BUM packet
   reaches PE2, PE2 sends a copy of the packet to CE3 and CE1.  In
   addition, PE2 sends a copy of the packet to PE1 through the bypass
   VXLAN tunnel between PE1 and PE2.  After the copy of the packet
   reaches PE1, PE1 sends it to CE2, not to the CPE or CE1.  In this
   way, CE1 receives only one copy of the packet.






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   Using the topology in Figure 3, after a BUM packet from CE2 reaches
   PE1, PE1 sends a copy of the packet to CE1 and the CPE.  In addition,
   PE1 sends a copy of the packet to PE2 through the bypass VXLAN tunnel
   between PE1 and PE2.  After the copy of the packet reaches PE2, PE2
   sends it to CE3, not to the CPE or CE1.

   Using the topology in Figure 3, after a BUM packet from CE1 reaches
   PE1, PE1 sends a copy of the packet to CE2 and the CPE.  In addition,
   PE1 sends a copy of the packet to PE2 through the bypass VXLAN tunnel
   between PE1 and PE2.  After the copy of the packet reaches PE2, PE2
   sends it to CE3, not to the CPE or CE1.

7.  IANA Considerations

   IANA is requested to assign two new Extended Community attribute
   SubTypes as follows:

7.1.  IPv4 Specific

     +================+=================================+============+
     | Sub-Type Value |               Name              | Reference  |
     +================+=================================+============+
     |      TBA1      | Bypass VXLAN Extended Community | [this doc] |
     +----------------+---------------------------------+------------+

                                  Table 1

7.2.  IPv6 Specific

     +================+=================================+============+
     | Sub-Type Value |               Name              | Reference  |
     +================+=================================+============+
     |      TBA2      | Bypass VXLAN Extended Community | [this doc] |
     +----------------+---------------------------------+------------+

                                  Table 2

8.  Security Considerations

   TBD

   For general EVPN Security Considerations, see [RFC7432].

9.  Normative References







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   [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>.

   [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>.

   [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>.

10.  Informative References

   [RFC7209]  Sajassi, A., Aggarwal, R., Uttaro, J., Bitar, N.,
              Henderickx, W., and A. Isaac, "Requirements for Ethernet
              VPN (EVPN)", RFC 7209, DOI 10.17487/RFC7209, May 2014,
              <https://www.rfc-editor.org/info/rfc7209>.

   [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>.

Acknowledgements

   The authors would like to thank the following for their comments and
   review of this document: TBD.

Contributors

   Thanks to the following who made significant contributions to this
   document:

   Haibo Wang
   Huawei Technologies
   Huawei Blduilding, No.156 Beiqing Rdoad
   Beijing
   100095
   China
   Email: rainsword.wang@huawei.com






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Authors' Addresses

   Donald Eastlake
   Futurewei Technologies
   2386 Panoramic Circle
   Apopka, FL 32703
   United States of America
   Phone: +1-508-333-2270
   Email: d3e3e3@gmail.com, donald.eastlake@futurewei.com


   Zhenbin Li
   Huawei Technologies
   Huawei Blduilding, No.156 Beiqing Rdoad
   Beijing
   100095
   China
   Email: lizhenbin@huawei.com


   Shunwan Zhuang
   Huawei Technologies
   Huawei Blduilding, No.156 Beiqing Rdoad
   Beijing
   100095
   China
   Email: zhuangshunwan@huawei.com


   Russ White
   Juniper Networks
   Email: russ@riw.us



















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