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Versions: 00 01 02 03 04                                                
BESS Working Group                                               W. Wang
Internet-Draft                                                   A. Wang
Intended status: Standards Track                           China Telecom
Expires: September 13, 2021                                      H. Wang
                                                     Huawei Technologies
                                                          March 12, 2021


                    Layer-3 Accessible EVPN Services
                 draft-wang-bess-l3-accessible-evpn-04

Abstract

   This draft describes layer-3 accessible EVPN service interfaces
   according to [RFC7432], and proposes a new solution which can
   simplify the deployment of layer-3 accessible EVPN service.  This
   solution allows each PE in EVPN network to maintain only one IP-VRF.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 13, 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   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




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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   4
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Service Interfaces in layer-3 accessible EVPN . . . . . . . .   5
   5.  Solutions of LSI-aware bundle service interface . . . . . . .   6
   6.  Protocol Extensions . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  Forwarding Plane  . . . . . . . . . . . . . . . . . . . .   8
       6.1.1.  Extensions to VxLAN . . . . . . . . . . . . . . . . .   8
     6.2.  Control Plane . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   [RFC7432]defines three service interfaces for layer-2 accessible
   EVPN: VLAN-Based Service Interface, VLAN-Bundle Service Interface and
   VLAN-Aware Bundle Service Interface.  These three types of service
   interfaces can realize the isolation of layer-2 traffic of customers
   in different ways, as shown in Figure 1.

























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                1:1           1:1
        +------+   +---------+   +------+
        |VID 11+---+  EVI 1  +---+VID 12|
        +------+   +---------+   +------+
        |VID 21+---+  EVI 2  +---+VID 22|
        +------+   +---------+   +------+
        |VID 31+---+  EVI 3  +---+VID 32|
        +------+   +---------+   +------+
        |VID 41+---+  EVI 4  +---+VID 42|
        +------+   +---------+   +------+

           VLAN-based Service Interface



               N:1                1:N
     +------+        +---------+        +------+
     |VID 11---------+         +--------+VID 12|
     +------+        +         +        +------+
     |VID 21+--------+         +--------+VID 22|
     +------+        +  EVI 1  +        +------+
     |VID 31+--------+         +--------+VID 32|
     +------+        +         +        +------+
     |VID 41+--------+         +--------+VID 42|
     +------+        +---------+        +------+

          VLAN-bundle Service Interface


            N:1                        1:N
               +----------------------+
     +------+  |+--------------------+|  +------+
     |VID 11+--++ Broadcast Domain 1 ++--+VID 12|
     +------+  |+--------------------+|  +------+
     |VID 21+--++ Broadcast Domain 2 ++--+VID 22|
     +------+  |+--------------------+|  +------+
     |VID 31+--++ Broadcast Domain 3 ++--+VID 32|
     +------+  |+--------------------+|  +------+
     |VID 41+--++ Broadcast Domain 4 ++--+VID 42|
     +------+  |+--------------------+|  +------+
               |                      |
               |        EVI 1         |
               +----------------------+

         VLAN-Aware Bundle Service Interface


              Figure 1: EVPN Service Interfaces Overview



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   For VLAN-based service interface, there is a one to one mapping
   between VID and EVI.  Each EVI has a single broadcast domain so that
   traffic from different customers can be isolated.

   For VLAN-bundle service interface, there is a N to one mapping
   between VID and EVI.  Each EVI has a single broadcast domain, but the
   MAC address MUST be unique that can be used for customer traffic
   isolation.

   For VLAN-aware bundle service interface, there is a N to one mapping
   between VID and EVI.  Each EVI has multiple broadcast domains while
   the MAC address can overlap.  One broadcast domain corresponds to one
   VID, which can be used to customer traffic isolation.

   In the scenarios corresponding to these service interfaces, CE-PE
   should be placed in the same Layer-2 network.  In most of provider
   network, CE-PE need to cross a Layer-3 network, then the above
   service interfaces should be extended to adapt to the layer-3
   network.

   In this draft, we describe three layer-3 accessible interfaces for
   EVPN, summarize the existing layer-3 accessible EVPN solutions, and
   propose a new solution which can simplify the depolyment of layer-3
   accessible EVPN service.

2.  Conventions used in this document

   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 [RFC2119] .

3.  Terminology

   The following terms are defined in this draft:

   o  CE: Client Edge

   o  PE: Provider Edge

   o  EVPN: BGP/MPLS Ethernet VPN, defined in [RFC7432]

   o  VxLAN: Virtual eXtensible Local Area Network, defined in [RFC7348]

   o  IPSec: Internet Protocol Security, defined in [RFC4301]







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4.  Service Interfaces in layer-3 accessible EVPN

   In most of provider network, CE-PE need to cross a Layer-3 network.
   With this scenario, service interfaces defined in [RFC7432] should be
   extended to adapt to the layer-3 network.  To achieve the traffic
   isolation, tunnel encapsulation technologies can be used.

   We define Logical Session Identifier(LSI) to distinguish the packets
   from different tunnels, which is related to VNI/SPI.  The length of
   LSI is 16 bits.

   The layer-3 accessible interfaces for EVPN are shown in Figure 2,
   refer to [RFC7432]

                1:1           1:1
       +------+   +---------+   +------+
       |LSI 11+---+ IP-VRF1 +---+LSI 12|
       +------+   +---------+   +------+
       |LSI 21+---+ IP-VRF2 +---+LSI 22|
       +------+   +---------+   +------+
       |LSI 31+---+ IP-VRF3 +---+LSI 32|
       +------+   +---------+   +------+
       |LSI 41+---+ IP-VRF4 +---+LSI 42|
       +------+   +---------+   +------+

           LSI-based Service Interface



              N:1                1:N
    +------+        +---------+        +------+
    |LSI 11---------+         +--------+LSI 12|
    +------+        +         +        +------+
    |LSI 21+--------+         +--------+LSI 22|
    +------+        + IP-VRF1 +        +------+
    |LSI 31+--------+         +--------+LSI 32|
    +------+        +         +        +------+
    |LSI 41+--------+         +--------+LSI 42|
    +------+        +---------+        +------+

          LSI-bundle Service Interface


           N:1                        1:N
              +----------------------+
    +------+  |+--------------------+|  +------+
    |LSI 11+--++   Logical Plane 1  ++--+LSI 12|
    +------+  |+--------------------+|  +------+



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    |LSI 21+--++   Logical Plane 2  ++--+LSI 22|
    +------+  |+--------------------+|  +------+
    |LSI 31+--++   Logical Plane 3  ++--+LSI 32|
    +------+  |+--------------------+|  +------+
    |LSI 41+--++   Logical Plane 4  ++--+LSI 42|
    +------+  |+--------------------+|  +------+
              |                      |
              |       IP-VRF 1       |
              +----------------------+

         LSI-Aware Bundle Service Interface



           Figure 2: Layer-3 accessible EVPN Service Interfaces Overview

   For LSI-based service interface, there is a one to one mapping
   between LSI and IP-VRF.  Each IP-VRF has a single logical plane so
   that traffic from different customers can be isolated.

   For LSI-bundle service interface, there is a N to one mapping between
   LSI and IP-VRF.  Each IP-VRF has a single logical plane, but the IP
   address MUST be unique that can be used for customer traffic
   isolation.

   For LSI-aware bundle service interface, there is a N to one mapping
   between LSI and IP-VRF.  Each IP-VRF has multiple logical planes
   while the IP address can overlap.  One logical plane corresponds to
   one LSI, which can be used to customer traffic isolation.

5.  Solutions of LSI-aware bundle service interface

   Let's assume a scenario as shown in Figure 3.  PE1, PE2 and PE3 are
   EVPN peers, the customer data transmission between PEs relies on
   VxLAN.  CE1, CE2 and CE3 are connected to the sites of customer for
   its department A and B.















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                                  Department A

                                 Department B
                                    +---+
                                    |CE1|
                                    +-+-+
                  +-------------------+------------------+
                  |                 +-+-+                |
                  |     +-----------+PE1+----------+     |
                  |     |           +---+          |     |
                  |     |                          |     |
                  |     |                          |     |
                  |     |                          |     |
   Department A   |     |                          |     |  Department A
                  |     |                          |     |
   Department B   |     |                          |     |  Department B
           +---+  |   +++-+                      +-+++   |  +---+
           |CE2+--+---+PE2+----------------------+PE3+---+--+CE3|
           +---+  |   +---+                      +---+   |  +---+
                  |                                      |
                  |                                      |
                  |                  EVPN                |
                  +--------------------------------------+



          Figure 3: LSI-aware bundle service interface scenario

   If each VNI has its own IP-VRF, each PE and CE maintain an IP-VRF for
   each deployment.  In this situation, customer traffic can be isolated
   by different VNIs, and there is no need for extending control plane/
   forwarding plane protocols.

   For deployment, we expect a simpler way, such as assign an IP-VRF to
   each customer, not to each department.  That is to say, all VNIs
   share one IP-VRF on PEs.  In this situation, each CE still maintain
   an IP-VRF for each deployment, but each PE maintains only one VRF for
   all deployments.  In this situation, customer traffic cannot be
   isolated by VNIs.  We propose a solution for this scenario:

   o  Using LSI information to identify different customer routes /
      traffic.  As described above, LSI can be generated by VNI/SPI, and
      there is a one to one mapping between LSI and VNI/SPI.  PEs should
      maintain the mapping table of LSI and VNI/SPI, so that they can
      distinguish different customer routes / traffic.  LSI information
      can be transmitted by using Ethernet Tag ID or a newly defined ESI
      type.




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   o  TBD (more solutions are welcome).

6.  Protocol Extensions

6.1.  Forwarding Plane

6.1.1.  Extensions to VxLAN

   When the forwarding plane uses VxLAN tunnel technologes, we should
   extend the VxLAN GPE header to carry the LSI information, the
   extentions to the VxLAN GPE header is shown in Figure 4:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |R|S|Ver|I|P|B|O|               LSI             |Next Protocol  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                VXLAN Network Identifier (VNI) |   Reserved    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 4: The extentions to VxLAN GPE header

   We define a S bit.  If S is set to 1, it means the field after O bit
   contains LSI information.

6.2.  Control Plane

   We proposed two methods to identify the routes that related to
   different LSI information:

   o  Reusing the Ethernet Tag ID.  This method requires the update of
      [I-D.ietf-bess-evpn-prefix-advertisement] (Etherenet Tag ID is set
      to 0 for route type 5), and may arises some confuse with the
      original defination of Ethernet Tag ID.

   o  Using the newly defined ESI type as shown in Figure 5.  This
      method can preserve the original purpose of ESI defination (multi-
      homing).

                 +---+---+---+---+---+---+---+---+---+---+
                 | T | Reserved  | CE Identifier |  LSI  |
                 +---+---+---+---+---+---+---+---+---+---+


                       Figure 5: The format of new ESI type

   Where:




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   o  T (1 octet): specifys the ESI Type.  The recommended value is
      0x06.

   o  CE Identifier (3 octets): the route ID/IPv4 address of CE.

   o  LSI (2 octets): the LSI information.

   Since the length of LSI is 16 bits, while the length of Ethernet Tag
   ID and ESI are 80 bits and 32 bits, respectively.  We can only use
   the lower 16 bits of Ethernet Tag ID / ESI field to carry LSI
   information, the other locations MUST set to 0.

7.  Security Considerations

   TBD

8.  IANA Considerations

   This draft extends the VxLAN GPE header, S bit of Flag and LSI field
   are added:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |R|S|Ver|I|P|B|O|               LSI             |Next Protocol  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                VXLAN Network Identifier (VNI) |   Reserved    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   This draft also define a new ESI type:

                  +---+---+---+---+---+---+---+---+---+---+
                  | T | Reserved  | CE Identifier |  LSI  |
                  +---+---+---+---+---+---+---+---+---+---+

9.  Normative References

   [I-D.ietf-bess-evpn-prefix-advertisement]
              Rabadan, J., Henderickx, W., Drake, J., Lin, W., and A.
              Sajassi, "IP Prefix Advertisement in EVPN", draft-ietf-
              bess-evpn-prefix-advertisement-11 (work in progress), May
              2018.

   [I-D.ietf-bess-mvpn-evpn-aggregation-label]
              Zhang, Z., Rosen, E., Lin, W., Li, Z., and I. Wijnands,
              "MVPN/EVPN Tunnel Aggregation with Common Labels", draft-
              ietf-bess-mvpn-evpn-aggregation-label-05 (work in
              progress), January 2021.



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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>.

   [RFC2890]  Dommety, G., "Key and Sequence Number Extensions to GRE",
              RFC 2890, DOI 10.17487/RFC2890, September 2000,
              <https://www.rfc-editor.org/info/rfc2890>.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <https://www.rfc-editor.org/info/rfc4301>.

   [RFC7348]  Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
              L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
              eXtensible Local Area Network (VXLAN): A Framework for
              Overlaying Virtualized Layer 2 Networks over Layer 3
              Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
              <https://www.rfc-editor.org/info/rfc7348>.

   [RFC7432]  Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
              Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
              Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
              2015, <https://www.rfc-editor.org/info/rfc7432>.

Authors' Addresses

   Wei Wang
   China Telecom
   Beiqijia Town, Changping District
   Beijing, Beijing  102209
   China

   Email: weiwang94@foxmail.com


   Aijun Wang
   China Telecom
   Beiqijia Town, Changping District
   Beijing, Beijing  102209
   China

   Email: wangaj3@chinatelecom.cn








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   Haibo Wang
   Huawei Technologies
   Huawei Building, No.156 Beiqing Rd.
   Beijing, Beijing  100095
   China

   Email: rainsword.wang@huawei.com












































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