EVPN control plane for Geneve
draft-ietf-bess-evpn-geneve-02

Document Type Active Internet-Draft (bess WG)
Authors Sami Boutros  , Ali Sajassi  , John Drake  , Jorge Rabadan  , Sam Aldrin 
Last updated 2021-06-05
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BESS Workgroup                                           S. Boutros, Ed.
Internet-Draft                                                     Ciena
Intended status: Informational                                A. Sajassi
Expires: December 7, 2021                                  Cisco Systems
                                                                J. Drake
                                                        Juniper Networks
                                                              J. Rabadan
                                                                   Nokia
                                                               S. Aldrin
                                                                  Google
                                                            June 5, 2021

                     EVPN control plane for Geneve
                     draft-ietf-bess-evpn-geneve-02

Abstract

   This document describes how Ethernet VPN (EVPN) control plane can be
   used with Network Virtualization Overlay over Layer 3 (NVO3) Generic
   Network Virtualization Encapsulation (Geneve) encapsulation for NVO3
   solutions.

   EVPN control plane can also be used by Network Virtualization Edges
   (NVEs) to express Geneve tunnel option TLV(s) supported in the
   transmission and/or reception of Geneve encapsulated data packets.

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
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   This Internet-Draft will expire on December 7, 2021.

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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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Abbreviations and Terminology . . . . . . . . . . . . . . . .   3
   4.  GENEVE extension  . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Ethernet option TLV . . . . . . . . . . . . . . . . . . .   4
   5.  BGP Extensions  . . . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  Geneve Tunnel Option Types sub-TLV  . . . . . . . . . . .   6
   6.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The Network Virtualization over Layer 3 (NVO3) solutions for network
   virtualization in data center (DC) environment are based on an IP-
   based underlay.  An NVO3 solution provides layer 2 and/or layer 3
   overlay services for virtual networks enabling multi-tenancy and
   workload mobility.  The NVO3 working group has evaluated different
   dataplane encapsulations.  The Generic Network Virtualization
   Encapsulation [I-D.ietf-nvo3-geneve] has been recently recommended to
   be the proposed standard for NVO3 encapsulation.

   This document describes how the EVPN control plane can signal Geneve
   encapsulation type in the BGP Tunnel Encapsulation Extended Community
   defined in [I-D.ietf-idr-tunnel-encaps].  In addition, this document
   defines how to communicate the Geneve tunnel option types in a new

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   BGP Tunnel Encapsulation Attribute sub-TLV.  The Geneve tunnel
   options are encapsulated as TLVs after the Geneve base header in the
   Geneve packet as described in [I-D.ietf-nvo3-geneve].

   [I-D.ietf-nvo3-encap] recommends that a control plane determine how
   Network Virtualization Edges (NVEs) use the GENEVE option TLVs when
   sending/receiving packets.  In particular, the control plane
   negotiates the subset of option TLVs supported, their order and the
   total number of option TLVs allowed in the packets.  This negotiation
   capability allows, for example, interoperability with hardware-based
   NVEs that can process fewer options than software-based NVEs.

   This EVPN control plane extension will allow an NVE to express what
   Geneve option TLV types it is capable of receiving from, or sending
   to, over the Geneve tunnel with its peers.

   In the datapath, a transmitting NVE MUST NOT encapsulate a packet
   destined to another NVE with any option TLV(s) the receiving NVE is
   not capable of processing.

2.  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 [RFC2119].

3.  Abbreviations and Terminology

   NVO3: Network Virtualization Overlays over Layer 3

   GENEVE: Generic Network Virtualization Encapsulation.

   NVE: Network Virtualization Edge.

   VNI: Virtual Network Identifier.

   MAC: Media Access Control.

   OAM: Operations, Administration and Maintenance.

   PE: Provide Edge Node.

   CE: Customer Edge device e.g., host or router or switch.

   EVPN: Ethernet VPN.

   EVI: An EVPN instance spanning the Provider Edge (PE) devices
   participating in that EVPN.

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   MAC-VRF: A Virtual Routing and Forwarding table for Media Access
   Control (MAC) addresses on a PE.

4.  GENEVE extension

   This document adds an extension to the [I-D.ietf-nvo3-geneve]
   encapsulation that are relevant to the operation of EVPN.

4.1.  Ethernet option TLV

   [I-D.ietf-bess-evpn-overlay] describes when an ingress NVE uses
   ingress replication to flood unknown unicast traffic to the egress
   NVEs, the ingress NVE needs to indicate to the egress NVE that the
   Encapsulated packet is a BUM traffic type.  This is required to avoid
   transient packet duplication in all-active multi-homing scenarios.
   For GENEVE, we need a bit to for this purpose.

   [RFC8317] uses MPLS label for leaf indication of BUM traffic
   originated from a leaf AC in an ingress NVE so that the egress NVEs
   can filter BUM traffic toward their leaf ACs.  For GENEVE, we need a
   bit for this purpose.

   Although the default mechanism for split-horizon filtering of BUM
   traffic on an Ethernet segment for IP-based ecnapsulations such as
   VxLAN, GPE, NVGRE, and GENVE, is local-bias as defined in section
   8.3.1 of [I-D.ietf-bess-evpn-overlay], there can be an incentive to
   leverage the same split-horizon filtering mechanism of [RFC7432] that
   uses a 20- bit MPLS label so that a) the a single filtering mechanism
   is used for all encapsulation types and b) the same PE can
   participate in a mix of MPLS and IP encapsulations.  For this purpose
   a 20-bit label field MAY be defined for GENVE encapsulation.  The
   support for this label is optional.

   If an NVE wants to use local-bias procedure, then it sends the new
   option TLV without ESI-label (e.g., length=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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Option Class=Ethernet     |Type=0        |B|L|R| Len=0x1  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   If an NVE wants to use ESI-label, then it sends the new option TLV
   with ESI-label (e.g., length=8)

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       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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Option Class=Ethernet     |Typ=EVPN-OPTION|B|L|R| Len=0x2 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       Rsvd  |             Source-ID                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   - Option Class is set to Ethernet (new Option Class requested to
   IANA)

   - Type is set to EVPN-OPTION (new type requested to IANA) and C bit
   must be set.

   - B bit is set to 1 for BUM traffic.

   - L bit is set to 1 for Leaf-Indication.

   - R bit is set to 1 for Root-Indication.

   - Source-ID is a 24-bit value that encodes the ESI-label value
   signaled on the EVPN Autodiscovery per-ES routes, as described in
   [RFC7432] for multi-homing and [RFC8317] for leaf-to-leaf BUM
   filtering.  The ESI-label value is encoded in the high-order 20 bits
   of the Source-ESI field.

   The egress NVEs that make use of ESIs in the data path because they
   have a local multi-homed ES or support [RFC8317] SHOULD advertise
   their Ethernet A-D per-ES routes along with the Geneve tunnel sub-TLV
   and in addition to the ESI-label Extended Community.  The ingress NVE
   can then use the Ethernet option-TLV when sending GENEVE packets
   based on the [RFC7432] and [RFC8317] procedures.  The egress NVE will
   use the Source-ID field in the received packets to make filtering
   decisions.

   Note that [I-D.ietf-bess-evpn-overlay] modifies the [RFC7432] split-
   horizon procedures for NVO3 tunnels using the "local-bias" procedure.
   "Local-bias" relies on tunnel IP source address checks (instead of
   ESI-labels) to determine whether a packet can be forwarded to a local
   ES.

   While "local-bias" MUST be supported along with GENEVE encapsulation,
   the use of the Ethernet option-TLV is RECOMMENDED to follow the same
   procedures used by EVPN MPLS.

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   An ingress NVE using ingress replication to flood BUM traffic MUST
   send B=1 in all the GENEVE packets that encapsulate BUM frames.  An
   egress NVE SHOULD determine whether a received packet encapsulates a
   BUM frame based on the B bit.  The use of the B bit is only relevant
   to GENEVE packets with Protocol Type 0x6558 (Bridged Ethernet).

5.  BGP Extensions

   As per [I-D.ietf-bess-evpn-overlay] the BGP Encapsulation extended
   community defined in [I-D.ietf-idr-tunnel-encaps] is included with
   all EVPN routes advertised by an egress NVE.

   This document specifies a new BGP Tunnel Encapsulation Type for
   Geneve and a new Geneve tunnel option types sub-TLV as described
   below.

5.1.  Geneve Tunnel Option Types sub-TLV

   The Geneve tunnel option types is a new BGP Tunnel Encapsulation
   Attribute Sub-TLV.

                         +-----------------------------------+
                         |      Sub-TLV Type (1 Octet)       |
                         +-----------------------------------+
                         |     Sub-TLV Length (1 or 2 Octets)|
                         +-----------------------------------+
                         |     Sub-TLV Value (Variable)      |
                         |                                   |
                         +-----------------------------------+

           Figure 1: Geneve tunnel option types sub-TLV

   The Sub-TLV Type field contains a value in the range from 192-252.
   To be allocated by IANA.

   Sub-TLV value MUST match exactly the first 4-octets of the option TLV
   format.  For instance, if we need to signal support for two option
   TLVs:

       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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Option Class         |      Type     |R|R|R| Length  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Option Class         |      Type     |R|R|R| Length  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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   An NVE receiving the above sub-TLV, MUST send GENEVE packets to the
   originator NVE with only the option TLVs the receiver NVE is capable
   of receiving, and following the same order.

   The above sub-TLV(s) MAY be included with only Ethernet A-D per-ES
   routes.

6.  Operation

   The following figure shows an example of an NVO3 deployment with
   EVPN.

                                 +--------------+
                                 |              |
                 +---------+     |     WAN      |    +---------+
         +----+  |         |   +----+        +----+  |         |  +----+
         |NVE1|--|         |   |ASBR|        |ASBR|  |         |--|NVE3|
         +----+  |IP Fabric|---| 1  |        |  2 |--|IP Fabric|  +----+
         +----+  |         |   +----+        +----+  |         |  +----+
         |NVE2|--|         |     |              |    |         |--|NVE4|
         +----+  +---------+     +--------------+    +---------+  +----+

         |<------ DC 1 ----->                        <---- DC2  ------>|

                 Figure 2: Data Center Interconnect with ASBR

   iBGP sessions are established between NVE1, NVE2, ASBR1, possibly via
   a BGP route-reflector.  Similarly, iBGP sessions are established
   between NVE3, NVE4, ASBR2.

   eBGP sessions are established among ASBR1 and ASBR2.

   All NVEs and ASBRs are enabled for the EVPN SAFI and exchange EVPN
   routes.  For inter-AS option B, the ASBRs re-advertise these routes
   with NEXT_HOP attribute set to their IP addresses as per [RFC4271].

   NVE1 sets the BGP Encapsulation extended community defined in all
   EVPN routes advertised.  NVE1 sets the BGP Tunnel Encapsulation
   Attribute Tunnel Type to Geneve tunnel encapsulation, and sets the
   Tunnel Encapsulation Attribute Tunnel sub-TLV for the Geneve tunnel
   option types with all the Geneve option types it can transmit and
   receive.

   All other NVE(s) learn what Geneve option types are supported by NVE1
   through the EVPN control plane.  In the datapath, NVE2, NVE3 and NVE4
   MUST only encapsulate overlay packets with the Geneve option TLV(s)

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   that NVE1 is capable of receiving, and in case more than one option
   TLV is being used, they MUST be in the order specified by NVE1.

   A PE advertises the BGP Encapsulation extended community defined in
   [RFC5512] if it supports any of the encapsulations defined in
   [I-D.ietf-bess-evpn-overlay].  A PE advertises the BGP Tunnel
   Encapsulation Attribute defined in [I-D.ietf-idr-tunnel-encaps] if it
   supports Geneve encapsulation.

7.  Security Considerations

   The mechanisms in this document use EVPN control plane as defined in
   [RFC7432].  Security considerations described in [RFC7432] are
   equally applicable.

   This document uses IP-based tunnel technologies to support data plane
   transport.  Security considerations described in [RFC7432] and in
   [I-D.ietf-bess-evpn-overlay] are equally applicable.

8.  IANA Considerations

   IANA is requested to allocate the following:

       BGP Tunnel Encapsulation Attribute
         Tunnel Type:

         XX     Geneve Encapsulation

      BGP Tunnel Encapsulation Attribute Sub-TLVs a Code point from the
      range of 192-252 for Geneve tunnel option types sub-TLV.

      IANA is requested to assign a new option class from the "Geneve
      Option Class" registry for the Ethernet option TLV.

         Option Class    Description
         ------------    ---------------
            XXXX         Ethernet option

9.  Acknowledgements

   The authors wish to thank T.  Sridhar, for his input, feedback, and
   helpful suggestions.

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10.  References

10.1.  Normative References

   [I-D.ietf-bess-evpn-overlay]
              Sajassi, A., Drake, J., Bitar, N., Shekhar, R., Uttaro,
              J., and W. Henderickx, "A Network Virtualization Overlay
              Solution Using Ethernet VPN (EVPN)", draft-ietf-bess-evpn-
              overlay-12 (work in progress), February 2018.

   [I-D.ietf-idr-tunnel-encaps]
              Patel, K., Velde, G. V. D., Sangli, S. R., and J. Scudder,
              "The BGP Tunnel Encapsulation Attribute", draft-ietf-idr-
              tunnel-encaps-22 (work in progress), January 2021.

   [I-D.ietf-nvo3-encap]
              Boutros, S., "NVO3 Encapsulation Considerations", draft-
              ietf-nvo3-encap-05 (work in progress), February 2020.

   [I-D.ietf-nvo3-geneve]
              Gross, J., Ganga, I., and T. Sridhar, "Geneve: Generic
              Network Virtualization Encapsulation", draft-ietf-
              nvo3-geneve-16 (work in progress), March 2020.

   [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>.

   [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>.

   [RFC5512]  Mohapatra, P. and E. Rosen, "The BGP Encapsulation
              Subsequent Address Family Identifier (SAFI) and the BGP
              Tunnel Encapsulation Attribute", RFC 5512,
              DOI 10.17487/RFC5512, April 2009,
              <https://www.rfc-editor.org/info/rfc5512>.

   [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>.

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   [RFC8317]  Sajassi, A., Ed., Salam, S., Drake, J., Uttaro, J.,
              Boutros, S., and J. Rabadan, "Ethernet-Tree (E-Tree)
              Support in Ethernet VPN (EVPN) and Provider Backbone
              Bridging EVPN (PBB-EVPN)", RFC 8317, DOI 10.17487/RFC8317,
              January 2018, <https://www.rfc-editor.org/info/rfc8317>.

10.2.  Informative References

   [RFC7365]  Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
              Rekhter, "Framework for Data Center (DC) Network
              Virtualization", RFC 7365, DOI 10.17487/RFC7365, October
              2014, <https://www.rfc-editor.org/info/rfc7365>.

Authors' Addresses

   Sami Boutros (editor)
   Ciena
   USA

   Email: sboutros@ciena.com

   Ali Sajassi
   Cisco Systems
   USA

   Email: sajassi@cisco.com

   John Drake
   Juniper Networks
   USA

   Email: jdrake@juniper.net

   Jorge Rabadan
   Nokia
   USA

   Email: jorge.rabadan@nokia.com

   Sam Aldrin
   Google
   USA

   Email: aldrin.ietf@gmail.com

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