EVPN control plane for Geneve
draft-ietf-bess-evpn-geneve-06

BESS Workgroup                                           S. Boutros, Ed.
Internet-Draft                                                     Ciena
Intended status: Standards Track                              A. Sajassi
Expires: 27 November 2023                                  Cisco Systems
                                                                J. Drake
                                                        Juniper Networks
                                                              J. Rabadan
                                                                   Nokia
                                                               S. Aldrin
                                                                  Google
                                                             26 May 2023

                     EVPN control plane for Geneve
                     draft-ietf-bess-evpn-geneve-06

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

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   This Internet-Draft will expire on 27 November 2023.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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
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   provided without warranty as described in the Revised 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  . . . . . . . . . . . . . . . . . . . . . .   9
   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.

   This document describes how the EVPN control plane defined in
   [RFC7432] can signal Geneve encapsulation type in the BGP Tunnel
   Encapsulation Extended Community defined in [RFC9012].  In addition,
   this document defines how to communicate the Geneve tunnel option
   types using 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 [RFC8926].

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   [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, or sending 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.

   ES: Ethernet segment.

   ESI: Ethernet Segment Identifier.

   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 [RFC8926] encapsulation that
   is relevant to the operation of EVPN.

4.1.  Ethernet option TLV

   [RFC8365] 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 packet.  This is required to avoid transient packet duplication
   in all-active multi-homing scenarios.  For Geneve, we need a bit for
   this purpose.

   [RFC8317] uses an MPLS label for leaf indication of BUM traffic
   originated from a leaf attachment circuit (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 encapsulations such as
   VxLAN, GPE, NVGRE, and Geneve, is local-bias as defined in section
   8.3.1 of [RFC8365], 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 Geneve 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     |C|  EVPN-OPTION|B|L|R| Len=0x1 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 1: Ethernet Option TLV without ESI label

   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     |C|  EVPN-OPTION|B|L|R| Len=0x2 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       Rsvd  |             Source-ID                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 2: Ethernet Option TLV with ESI label

   Where:

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

   - Type is set to EVPN-OPTION with value = 0, 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-ID 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
   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 [RFC8365] 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 [RFC8365] the BGP Encapsulation extended community defined in
   [RFC9012] is included with all EVPN routes advertised by an egress
   NVE.

   This document uses the Geneve Encapsulation BGP Tunnel Encapsulation
   Typei from the IANA BGP Tunnel Encapsulation Types registry, Value =
   19.

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 3: 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:

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

                        Figure 4: Geneve Option TLVs

   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 5: 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].

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   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)
   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
   [RFC8365].  A PE advertises the BGP Tunnel Encapsulation Attribute
   defined in [RFC9012] if it supports Geneve encapsulation, setting the
   type to Geneve Encapsulation.

7.  Security Considerations

   The mechanisms in this document uses 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
   [RFC8365] are equally applicable.

8.  IANA Considerations

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

    Option Class Description     Reference
    ------------ --------------- -------------
    XXXX         Ethernet option This document

    IANA is requested to assign a new BGP Tunnel Encapsulation Attribute
    Sub-TLV from the BGP Tunnel Encapsulation Attribute Sub-TLVs
    registry.

    BGP Tunnel Attribute Sub-TLV Description               Reference
    ---------------------------- ------------------------- -------------
    XXXX                         Geneve tunnel option type This document

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9.  Acknowledgements

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

10.  References

10.1.  Normative References

   [I-D.ietf-nvo3-encap]
              Boutros, S. and D. E. Eastlake, "Network Virtualization
              Overlays (NVO3) Encapsulation Considerations", Work in
              Progress, Internet-Draft, draft-ietf-nvo3-encap-09, 7
              October 2022, <https://datatracker.ietf.org/doc/html/
              draft-ietf-nvo3-encap-09>.

   [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>.

   [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>.

   [RFC8365]  Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R.,
              Uttaro, J., and W. Henderickx, "A Network Virtualization
              Overlay Solution Using Ethernet VPN (EVPN)", RFC 8365,
              DOI 10.17487/RFC8365, March 2018,
              <https://www.rfc-editor.org/info/rfc8365>.

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   [RFC8926]  Gross, J., Ed., Ganga, I., Ed., and T. Sridhar, Ed.,
              "Geneve: Generic Network Virtualization Encapsulation",
              RFC 8926, DOI 10.17487/RFC8926, November 2020,
              <https://www.rfc-editor.org/info/rfc8926>.

   [RFC9012]  Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
              "The BGP Tunnel Encapsulation Attribute", RFC 9012,
              DOI 10.17487/RFC9012, April 2021,
              <https://www.rfc-editor.org/info/rfc9012>.

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
   United States of America
   Email: sboutros@ciena.com

   Ali Sajassi
   Cisco Systems
   United States of America
   Email: sajassi@cisco.com

   John Drake
   Juniper Networks
   United States of America
   Email: jdrake@juniper.net

   Jorge Rabadan
   Nokia
   United States of America
   Email: jorge.rabadan@nokia.com

   Sam Aldrin
   Google
   United States of America
   Email: aldrin.ietf@gmail.com

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