[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02

IDR                                                            S. Sangli
Internet-Draft                                                 R. Bonica
Intended status: Standards Track                   Juniper Networks Inc.
Expires: January 6, 2020                                    July 5, 2019


BGP based Virtual Private Network (VPN) Services over SRv6+ enabled IPv6
                                networks
                 draft-ssangli-idr-bgp-vpn-srv6-plus-01

Abstract

   This document defines BGP protocol extensions for encoding and
   carrying SRv6+ Per-Path Service Instruction information to support
   Virtual Private Network services.  This is applicable when the VPN
   services are offered in a SRv6+ enabled IPv6 network such that the
   VPN payload is transported over IPv6.  The Per-Path Service
   Instruction information is encoded in the IPv6 Destination Option
   Header in the IPv6 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
   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 January 6, 2020.

Copyright Notice

   Copyright (c) 2019 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



Sangli & Bonica          Expires January 6, 2020                [Page 1]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Per-Path Service Instruction Information  . . . . . . . . . .   3
   4.  Usage of Tunnel Encapsulation Attribute . . . . . . . . . . .   4
   5.  Procedures for Egress BGP Speaker . . . . . . . . . . . . . .   6
   6.  Procedures for Ingress BGP Speaker  . . . . . . . . . . . . .   6
   7.  BGP based L3 VPN services over IPv6 . . . . . . . . . . . . .   7
     7.1.  IPv4 VPN on SRv6+ enabled IPv6 Core . . . . . . . . . . .   7
     7.2.  IPv6 VPN on SRv6+ enabled IPv6 Core . . . . . . . . . . .   8
     7.3.  IPv4 Global Routes on SRv6+ enabled IPv6 Core . . . . . .   8
   8.  BGP based Ethernet VPN services over IPv6 . . . . . . . . . .   9
     8.1.  Ethernet Per ES Auto-Discovery (A-D) route  . . . . . . .   9
     8.2.  Ethernet per EVI Auto-Discovery (A-D) route . . . . . . .  10
     8.3.  MAC/IP Advertisement route  . . . . . . . . . . . . . . .  10
     8.4.  Inclusive Multicast Ethernet Route  . . . . . . . . . . .  11
     8.5.  IP Prefix Route . . . . . . . . . . . . . . . . . . . . .  11
   9.  Deployment Considerations . . . . . . . . . . . . . . . . . .  11
   10. Backward Compatibility  . . . . . . . . . . . . . . . . . . .  13
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  13
   12. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   13. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  13
     14.2.  Informative References . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Virtual Private Network (VPN) technologies allow network providers to
   emulate private networks with shared infrastructure.  For example,
   assume that a set of red sites, set of blue sites and a set of green
   sites connect to a provider network.  Furthermore, assume that red
   sites and blue sites wish to interconnect, exchange packets.
   However, the green sites wish to communicate with green sites only.
   The provider should allow its infrastructure network to scale to both
   the requirements without having to create multiple parallel network
   infrastructures.  The IETF has standardized many VPN technologies
   viz. Layer 3 VPN (L3VPN) [RFC4364], Layer 2 VPN (L2VPN) [RFC6624],
   Virtual Private LAN Service (VPLS) [RFC4761], [RFC4762], Ethernet VPN
   (EVPN) [RFC7432], Pseudowires [RFC8077] to enable Layer 3 and Layer 2
   VPN services.




Sangli & Bonica          Expires January 6, 2020                [Page 2]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   The aforementioned technologies leverage MPLS network architecture :

   o  to establish a MPLS tunnel from ingress PE to egress PE, thus
      making all P routers agnostic of VPN state.

   o  to provide demultiplexing abstraction in the tunnelled packet so
      the payload packet can be forwarded at the egress router based on
      Routing table and/or interface.

   In pure IPv6 deployments where there may be non-MPLS capable routers,
   it would be desirable to have alternate mechanism to provide VPN
   connectivity.  This document describes BGP extensions and procedures
   applicable for SRv6+ enabled IPv6 networks, to provide VPN services
   over BGP.

2.  Requirements Language

   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.

3.  Per-Path Service Instruction Information

   A SRv6+ [I-D.bonica-spring-srv6-plus] segment provides unidirectional
   connectivity from an ingress node to an egress node.  A SRv6+ path
   contains one or more such segments.  SRv6+ introduces the concept of
   Per-Segment Service Instruction and Per-Path Service Instruction.
   These instructions describe the additional packet processing
   performed on a node.  The Per-Segment Service Instruction is executed
   on the segment egress node while the Per-Path Service Instruction is
   executed on the path egress node.  The SR Path egress node advertises
   the reachability information to SR Path ingress node via Multi
   Protocol extensions in BGP [RFC4760].

   For providing VPN services, aforementioned BGP extensions rely on
   MPLS architecture [RFC3031].  The BGP extensions specify the new
   encoding for Network Layer Reachability Information (NLRI) to include
   the MPLS VPN labels [RFC8277].  Such a MPLS VPN label is associated
   with a forwarding decision in the VPN Routing Instance on the egress
   BGP Router.  The ingress BGP router will push the VPN label on the
   data packet destined to the egress BGP router.  The transport tunnel
   from ingress router to egress router can be MPLS or GRE or L2TPv3,
   but inner payload is a MPLS packet as described in [RFC4023],
   [RFC4817], [RFC7510].  The intermediate routers do not process the
   VPN label [a.k.a.] embedded label as described in
   [I-D.ietf-idr-tunnel-encaps].



Sangli & Bonica          Expires January 6, 2020                [Page 3]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   To provide BGP based VPN services on a non-MPLS IPv6 networks, it
   would be beneficial to retain the benefits of BGP protocol extensions
   while leveraging the benefits of IPv6 [RFC8200].
   [I-D.bonica-6man-vpn-dest-opt] describes SRv6+ paths as programmable
   with Per-Path Service Instructions (PPSI) that determine how egress
   nodes process SRv6+ payloads.  The PPSIs are carried in the PPSI
   Option encoded in the IPv6 Destination Option Header [RFC8200].

   The Per-Path Service Instruction (PPSI) Identifier is defined as
   follows:

   o  32 bit quantity.

   The PPSI Identifier have node-local significance and is assigned by
   the egress BGP router.  The value of zero is reserved.  The PPSI
   Identifier will serve 2 purposes.

   o  It MUST uniquely identify the VPN Routing Instance for L3VPN or
      identify an Ethernet Segment for EVPN or identify a leaf property
      for EVPN TREE upon which forwarding decision can be taken.

   o  It MAY provide information for special processing before the
      packet is forwarded.

   The structure of 3 octet PPSI Identifier will be updated in the next
   version of this document.

   The encoding of the Per-Path Service Instruction Identifier for VPNs
   is described in Section 7 and Section 8.

4.  Usage of Tunnel Encapsulation Attribute

   This document defines a new Tunnel type : SRv6+. The format is as per
   below.

   o  Tunnel Type (2 Octets) : To be assigned

   o  Tunnel Length (2 Octets) : 1

   o  Value : List of Sub-TLVs

   [I-D.ietf-idr-tunnel-encaps] defines many sub-TLVs for the tunnels.
   The encoding for them are as follows:

   o  Remote Endpoint sub-TLV : As per [I-D.ietf-idr-tunnel-encaps]

   o  Encapsulation sub-TLV : Not needed.




Sangli & Bonica          Expires January 6, 2020                [Page 4]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   o  IPv4 DS Field sub-TLV : Not needed.

   o  UDP Destination Port sub-TLV : Not needed.

   o  Protocol type sub-TLV : As per [I-D.ietf-idr-tunnel-encaps].

   o  Color Sub-TLV : As per [I-D.ietf-idr-tunnel-encaps].

   o  Embedded Label Handling sub-TLV : 2.

   o  MPLS Label Stack Sub-TLV : Not needed.

   o  Prefix SID Sub-TLV : Not Needed.

   The Tunnel Encapsulation Attribute is a an Optional Transitive
   attribute as described in [I-D.ietf-idr-tunnel-encaps].  This
   attribute with SRv6+ tunnel type MUST be present in the BGP update
   carrying the Network Layer Reachability Information encoded with the
   PPSI Information.  This document refers to the NLRI that is
   associated with SRv6+ Tunnel Encapsulation attribute as SRv6+_NLRI.
   The document [I.D.ietf-idr-tunnel-encaps-12] defines the encoding for
   sub-TLV as follows.

   o  Sub-TLV Type : 1 octet

   o  Sub-TLV Length : 1 or 2 octets

   o  Sub-TLV Value : defined per Sub-TLV as per below.

   The Remote Endpoint sub-TLV can specify the IPv6 address of the
   egress router as the final destination address of SRv6+ packet which
   is also referred to as SR Path destination address.  The sub-fields
   on this sub-TLV is encoded as below.

   o  Autonomous System Number : AS number of the IPv6 SR domain.

   o  Address Family : 2 (refers to IPv6).

   o  Address : IPv6 address of the egress interface present in SRv6+
      domain.

   The Value field may be set to 0 which indicates that next hop value
   in the NLRI should be chosen for the SRv6+ Path destination address.

   The Embedded Label Handling sub-TLV describes how the label field in
   the NLRI should be interpreted.

   o  Value : MUST be set to 2.



Sangli & Bonica          Expires January 6, 2020                [Page 5]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   The value of 2 indicates that the label field in the NLRI MUST be
   ignored at the ingress router.

5.  Procedures for Egress BGP Speaker

   The PPSI Information instructs the egress router to de-encapsulate
   the packet and forward the newly exposed payload inner packet through
   the specified interface or forward using the specified Routing
   Instance.  The PPSI Identifier described in Section 3 will be
   assigned by the egress BGP Router except in the case of EVPN per ES
   AD route when P2MP tunnel is used for delivering BUM traffic in EVPN.
   If P2MP tunnel is used to deliver BUM traffic for EVPN, the PPSI
   Identifier used to identify an Ethernet Segment is assigned by the
   upstream ingress BGP Router.  Otherwise, it is downstream assigned by
   the egress BGP router.

   When the egress BGP Speaker advertises the NLRI, it will include the
   PPSI Information in the encoding described in Section 7 and
   Section 8.  The egress BGP Speaker MUST include the Tunnel
   Encapsulation Attribute with Route type SRv6+ as described in
   Section 4 in such BGP updates.

   By tagging the BGP update with Tunnel Encapsulation attribute of
   SRv6+ type, the BGP Speaker informs how the SRv6+_NLRI should be
   decoded and processed by the receiving BGP Speaker.

   Via the Remote Tunnel Endpoint Sub-TLV encoding, the egress BGP
   router may specify the SRv6+ Path Destination Address.  The Protocol
   type Sub-TLV and the Color Sub-TLV may be used by the egress BGP
   router to influence the payload packets to be put on SRv6+ path.  The
   Embedded Label Handling Sub-TLV MUST be set to 2 to inform that the
   MPLS label field should be ignored.

   A single PPSI Identifier may be associated with all the prefixes in a
   Routing Instance or a unique PPSI Identifier may be associated for
   each prefix in the Routing Instance.  Similarly, a PPSI Identifier
   may be assigned to identify an Ethernet segment or leaf AC property
   by EVPN.  The choice is left to the Network Operator and is outside
   the scope of this document.

6.  Procedures for Ingress BGP Speaker

   Upon receiving a BGP update, the receiving BGP Speaker will look for
   Tunnel Encapsulation attribute.  If the tunnel type carried in the
   Tunnel Encapsulation attribute is SRv6+, the BGP updates is said to
   be carrying the SRv6+_NLRI and the Label field in the Network Layer
   Reachability Information is treated as Per-Path Service Instruction
   (PPSI) Identifier.



Sangli & Bonica          Expires January 6, 2020                [Page 6]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   The tuple (PPSI Identifier, Prefix) is programmed in the forwarding
   infrastructure of the router.  The manner in which this tuple is
   stored in the router is outside the scope of this document.  If SRv6+
   has been enabled on the router, such a tuple SHOULD be used for
   encoding the Destination Options Header as described in
   [I-D.bonica-6man-vpn-dest-opt].

   [I.D.ietf-idr-tunnel-encaps-12] describes how Remote Tunnel Endpoint
   Sub-TLV has to be processed.  It also describes the usage of the
   Protocol type Sub-TLV and the Color Sub-TLV.  This may be used by the
   ingress BGP router to select the payload packets that should be put
   on SRv6+ path.

   The Embedded Label Handling Sub-TLV value that is set to 2 indicates
   that ingress BGP router to ignore the MPLS label field.

7.  BGP based L3 VPN services over IPv6

   The Egress and Ingress BGP speakers form a BGP peering session to
   exchange a set of prefixes described in [RFC4271] and Multi protocol
   extensions [RFC4760].  The BGP Router capable of SRv6+ that is
   enabled to carry L3 VPN services over IPv6 networks should follow the
   procedures mentioned in Section 5 and Section 6.  The manner in which
   a BGP Router is configured for SRv6+ underlay and L3 VPN overlay is
   outside the scope of this document.

7.1.  IPv4 VPN on SRv6+ enabled IPv6 Core

   The IPv4 L3 VPN over IPv6 is defined in [RFC5549].  The MP_REACH NLRI
   and Tunnel Encapsulation attribute encoding is as per below:

   o  AFI : 1; SAFI : 128

   o  Length of the Next Hop : 16 (or 32 if Link Local)

   o  Network address of the Next Hop : IPv6 address of the egress BGP
      Router

   o  NLRI : IPv4-VPN routes

   o  Label : Per-Path Service Instruction Identifier

   o  Tunnel Encapsulation Path Attribute : SRv6+ Type as described in
      Section 4

   The PPSI Identifier is associated with VPN Routing Instance on the
   Egress PE.  The Tunnel Encapsulation attribute with SRv6+ type MUST
   be appended to the Path attributes associated with the NLRI.



Sangli & Bonica          Expires January 6, 2020                [Page 7]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


7.2.  IPv6 VPN on SRv6+ enabled IPv6 Core

   The IPv6 L3 VPN over IPv6 is defined in [RFC4659].  The MP_REACH NLRI
   and Tunnel Encapsulation attribute encoding is as per below:

   o  AFI : 2; SAFI : 128

   o  Length of the Next Hop : 16 (or 32 if Link Local)

   o  Network address of the Next Hop : IPv6 address of the egress BGP
      Router

   o  NLRI : IPv6-VPN routes

   o  Label : Per-Path Service Instruction Identifier

   o  Tunnel Encapsulation Path Attribute : SRv6+ Type as described in
      Section 4

   The PPSI Identifier is associated with VPN Routing Instance on the
   Egress PE.  The Tunnel Encapsulation attribute with SRv6+ type MUST
   be appended to the Path attribute associated with the NLRI.

7.3.  IPv4 Global Routes on SRv6+ enabled IPv6 Core

   The IPv4 L3 VPN over IPv6 is defined in [RFC5549].  The MP_REACH NLRI
   and Tunnel Encapsulation attribute encoding is per below:

   o  AFI : 1; SAFI : 1

   o  Length of the Next Hop : 16 (or 32 if Link Local)

   o  Network address of the Next Hop : IPv6 address of the egress BGP
      Router

   o  NLRI : IPv4 routes

   o  Label : Per-Path Service Instruction Identifier

   o  Tunnel Encapsulation Path Attribute : SRv6+ Type as described in
      Section 4

   The PPSI Identifier is associated with VPN Routing Instance on the
   Egress PE.  The Tunnel Encapsulation attribute with SRv6+ type MUST
   be appended to the Path attribute associated with the NLRI.






Sangli & Bonica          Expires January 6, 2020                [Page 8]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


8.  BGP based Ethernet VPN services over IPv6

   The [RFC7432] describes the BGP extensions for carrying the Ethernet
   Virtual Private Network Overlay on MPLS network.  It defines 4 types
   of EVPN NLRI.  This document specifies changes to certain fields for
   those NLRIs.

   o  Ethernet Auto-Discovery (A-D) route

   o  MAC/IP Advertisement route

   o  Inclusive Multicast Ethernet Tag route

   o  IP Prefix route

8.1.  Ethernet Per ES Auto-Discovery (A-D) route

   The MP_REACH and MP_UNREACH attributes will carry this route in the
   NLRI encoding described in [RFC7432].  In addition to Tunnel
   Encapsulation attribute encoding, this document recommends to follow
   the [RFC4732] encoding except the following.  For MPLS label carried
   in the Ethernet A-D per ESI route:

   o  MPLS label : Per [RFC7432], it is set to zero.

   o  Tunnel Encapsulation Path Attribute : SRv6+ Type as described in
      Section 4

   The MPLS label field is not part of the route but treated as route
   attribute.  For procedures and usage of this route, refer to
   [RFC7432].  The Tunnel Encapsulation attribute with SRv6+ type MUST
   be appended to the Path attribute associated with the NLRI.

   An EVPN Ethernet per ES A-D route is usually signaled together with
   an ESI label extended community.  For ESI Label carried in the ESI
   label extended community:

   o  ESI Label: Per-Path Service Instruction Identifier

   The Per-Path Service Instruction Identifier is used to identify an
   Ethernet segment attached to the BGP PE for EVPN.

   If P2MP tunnel is used to deliver BUM traffic, then this PPSI
   Identifier is upstream assigned by the ingress router, otherwise it
   is downstream assigned by the egress router.






Sangli & Bonica          Expires January 6, 2020                [Page 9]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


8.2.  Ethernet per EVI Auto-Discovery (A-D) route

   The MP_REACH and MP_UNREACH attributes will carry this route in the
   NLRI encoding described in [RFC7432].  In addition to Tunnel
   Encapsulation attribute encoding, this document recommends to follow
   the [RFC4732] encoding except the following:

   o  MPLS label : Per-Path Service Instruction Identifier

   o  Tunnel Encapsulation Path Attribute : SRv6+ Type as described in
      Section 4

   The MPLS label field is not part of the route but treated as route
   attribute.  For procedures and usage of this route, refer to
   [RFC7432].  The Tunnel Encapsulation attribute with SRv6+ type MUST
   be appended to the Path attribute associated with the NLRI.

   In addition, for EVPN E-tree service, this route may be signaled
   together with an E-Tree Extended Community as it is specified in
   [RFC8317].  For the leaf label carried in the E-Tree Extended
   Community:

   o  Leaf Label: Per-Path Service Instruction Identifier

   In case of EVPN E-tree service, the per-path service identifier
   carried in the E-Tree extended community is used to signal a leaf AC
   property.

   In the data plane, this PPSI identifier specified in the Destination
   Option header is used by an egress router to identify that a data
   packet is ingressed from a leaf AC such that appropriate forwarding
   decision can be made.

   If P2MP tunnel is used to deliver BUM traffic, then this PPSI
   Identifier is upstream assigned by the ingress router.  Otherwise it
   is downstream assigned by the egress router.

8.3.  MAC/IP Advertisement route

   The MP_REACH and MP_UNREACH attributes will carry this route in the
   NLRI encoding described in [RFC7432].  In addition to Tunnel
   Encapsulation attribute encoding, this document recommends to follow
   the [RFC4732] encoding except the following.

   o  MPLS label1 : Per-Path Service Instruction Identifier1

   o  MPLS label2 : Per-Path Service Instruction Identifier2




Sangli & Bonica          Expires January 6, 2020               [Page 10]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   o  Tunnel Encapsulation Path Attribute : SRv6+ Type as described in
      Section 4

   The MPLS label field is not part of the route but treated as route
   attribute.  For procedures and usage of this route, refer to
   [RFC7432].  The Tunnel Encapsulation attribute with SRv6+ type MUST
   be appended to the Path attribute associated with the NLRI.

8.4.  Inclusive Multicast Ethernet Route

   The MP_REACH and MP_UNREACH attributes will carry this route in the
   NLRI encoding described in [RFC7432].  In addition to Tunnel
   Encapsulation attribute encoding, this document recommends to follow
   the [RFC4732] encoding except the following.

   o  If MPLS label field in the PMSI Tunnel Attributed is non-zero, it
      is set to Per-Path Service Instruction Identifier.

   o  Tunnel Encapsulation Path Attribute : SRv6+ Type as described in
      Section 4

   The Tunnel Encapsulation attribute with SRv6+ type MUST be appended
   to the Path attribute associated with the NLRI.

8.5.  IP Prefix Route

   The MP_REACH and MP_UNREACH attributes will carry this route in the
   NLRI encoding described in [I-D draft-ietf-bess-evpn-prefix-
   advertisement].  In addition to Tunnel Encapsulation attribute
   encoding, this document recommends the following change:

   o  MPLS label: if it is non-zero, it is set to Per-Path Service
      Instruction Identifier.

   o  Tunnel Encapsulation Path Attribute : SRv6+ Type as described in
      Section 4

   The MPLS label field is not part of the route but treated as route
   attribute.  For procedures and usage of this route, refer to [I-D
   draft-ietf-bess-evpn-prefix-advertisement].  The Tunnel Encapsulation
   attribute with SRv6+ type MUST be appended to the Path attribute
   associated with the NLRI.

9.  Deployment Considerations

   This document proposes to reuse the NLRI encoding for BGP L3VPN and
   EVPN Network Layer Routing Information.  However, care should be
   taken when BGP VPN overlay services are enabled on SRv6+ underlay



Sangli & Bonica          Expires January 6, 2020               [Page 11]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   such that Tunnel Encapsulation Path attribute with SRv6+ type MUST be
   appended.  When a BGP router advertises SRv6+_NLRI, it MUST NOT
   remove the Tunnel Encapsulation Path attribute.

   The SRv6+ underlay is similar to other "tunnel" technologies viz
   MPLS, GRE, IP-in-IP, L2TPv3.  The egress and ingress BGP routers can
   be connected via one or more such underlay technologies.  A BGP
   speaker can advertise the VPN NLRI with the nexthop reachable via one
   or more such underlay paths.  Each such mechanism can co-exist
   together as ships-in-night.  However, when SRv6+_NLRI is advertised
   by a egress BGP speaker and received by an ingress BGP speaker, they
   MUST follow the procedures mentioned in this document.

   For migrating a BGP router to SRv6+ the following procedures can be
   followed.

   o  Operator will enable SRv6+ underlay on the ingress and egress
      routers identifying the SRv6+ path from ingress router's interface
      to egress router's interface.  The way to configure the ingress
      and egress routers are outside the scope of this document.

   o  SRv6+ enabled ingress BGP router will setup the additional
      information in the forwarding table such that it can append an
      IPv6 tunnel header and encode the PPSI Option in the Destination
      Options Header.

   o  SRv6+ enabled egress BGP router will setup the additional
      information in the forwarding table such that PPSI Identifier can
      be used to lookup to find the Routing Instance and make the
      forwarding decision.

   o  Operator will enable BGP VPN overlay over SRv6+ underlay on
      ingress router.  This means that ingress router will start looking
      for SRv6+_NLRI in the BGP updates.  The way to enable the BGP VPN
      overlay over SRv6+ underlay is outside the scope of this document.

   o  The operator will enable BGP VPN overlay over SRv6+ underlay on
      egress router.  With this, the egress router will create PPSI
      Identifier and associate it with Routing Instances.  It then
      advertises the SRv6+_NLRIs to the ingress BGP router.

   o  The ingress router will interpret the SRv6+_NLRIs and use PPSI
      identifier and follow the procedures in [I.D.  bonica-spring-srv6-
      plus-00.txt] to encode the Destination Options Header to forward
      the data packet.

   o  Now that SRv6+ path is setup between ingress and egress BGP
      routers, on the egress BGP router the Operator can migrate the



Sangli & Bonica          Expires January 6, 2020               [Page 12]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


      Routing Instances from MPLS VPN set of Instances to SRv6+ enabled
      set of Instances.  The way to configure Routing Instances to
      achieve the above is outside the scope of this document.

10.  Backward Compatibility

   The extension proposed in this document is backward compatible with
   procedures described for BGP enabled services.

11.  Security Considerations

   This document does not introduce any new security considerations
   beyond those already specified in [RFC4271], [RFC8277] and [I.D.ietf-
   idr-tunnel-encaps-12].

12.  IANA Considerations

   IANA is requested to assign a code point for SRv6+ Route Type for BGP
   Tunnel Encapsulation Path Attribute from BGP Tunnel Encapsulation
   Attribute Tunnel Types Registry.

13.  Acknowledgements

   The authors would like to thank Jeff Haas and Wen Lin for careful
   review and suggestions.

14.  References

14.1.  Normative References

   [I-D.bonica-6man-vpn-dest-opt]
              Bonica, R., Lenart, C., So, N., Xu, F., Presbury, G.,
              Chen, G., Zhu, Y., Yang, G., and Y. Zhou, "The IPv6
              Virtual Private Network (VPN) Context Information Option",
              draft-bonica-6man-vpn-dest-opt-05 (work in progress),
              March 2019.

   [I-D.bonica-spring-srv6-plus]
              Bonica, R., Hegde, S., Kamite, Y., Alston, A., Henriques,
              D., Halpern, J., and J. Linkova, "IPv6 Support for Segment
              Routing: SRv6+", draft-bonica-spring-srv6-plus-01 (work in
              progress), July 2019.

   [I-D.ietf-idr-tunnel-encaps]
              Patel, K., Velde, G., Ramachandra, S., and E. Rosen, "The
              BGP Tunnel Encapsulation Attribute", draft-ietf-idr-
              tunnel-encaps-12 (work in progress), May 2019.




Sangli & Bonica          Expires January 6, 2020               [Page 13]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,
              <https://www.rfc-editor.org/info/rfc791>.

   [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>.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, DOI 10.17487/RFC4303, December 2005,
              <https://www.rfc-editor.org/info/rfc4303>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", STD 89,
              RFC 4443, DOI 10.17487/RFC4443, March 2006,
              <https://www.rfc-editor.org/info/rfc4443>.

   [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>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

14.2.  Informative References

   [RFC3031]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
              Label Switching Architecture", RFC 3031,
              DOI 10.17487/RFC3031, January 2001,
              <https://www.rfc-editor.org/info/rfc3031>.

   [RFC4023]  Worster, T., Rekhter, Y., and E. Rosen, Ed.,
              "Encapsulating MPLS in IP or Generic Routing Encapsulation
              (GRE)", RFC 4023, DOI 10.17487/RFC4023, March 2005,
              <https://www.rfc-editor.org/info/rfc4023>.

   [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>.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <https://www.rfc-editor.org/info/rfc4364>.



Sangli & Bonica          Expires January 6, 2020               [Page 14]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   [RFC4659]  De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur,
              "BGP-MPLS IP Virtual Private Network (VPN) Extension for
              IPv6 VPN", RFC 4659, DOI 10.17487/RFC4659, September 2006,
              <https://www.rfc-editor.org/info/rfc4659>.

   [RFC4732]  Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet
              Denial-of-Service Considerations", RFC 4732,
              DOI 10.17487/RFC4732, December 2006,
              <https://www.rfc-editor.org/info/rfc4732>.

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              DOI 10.17487/RFC4760, January 2007,
              <https://www.rfc-editor.org/info/rfc4760>.

   [RFC4761]  Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
              LAN Service (VPLS) Using BGP for Auto-Discovery and
              Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007,
              <https://www.rfc-editor.org/info/rfc4761>.

   [RFC4762]  Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
              LAN Service (VPLS) Using Label Distribution Protocol (LDP)
              Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
              <https://www.rfc-editor.org/info/rfc4762>.

   [RFC4817]  Townsley, M., Pignataro, C., Wainner, S., Seely, T., and
              J. Young, "Encapsulation of MPLS over Layer 2 Tunneling
              Protocol Version 3", RFC 4817, DOI 10.17487/RFC4817, March
              2007, <https://www.rfc-editor.org/info/rfc4817>.

   [RFC5549]  Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network
              Layer Reachability Information with an IPv6 Next Hop",
              RFC 5549, DOI 10.17487/RFC5549, May 2009,
              <https://www.rfc-editor.org/info/rfc5549>.

   [RFC6624]  Kompella, K., Kothari, B., and R. Cherukuri, "Layer 2
              Virtual Private Networks Using BGP for Auto-Discovery and
              Signaling", RFC 6624, DOI 10.17487/RFC6624, May 2012,
              <https://www.rfc-editor.org/info/rfc6624>.

   [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>.







Sangli & Bonica          Expires January 6, 2020               [Page 15]


Internet-DrafBGP based VPN Services over SRv6+ enabled IPv6    July 2019


   [RFC7510]  Xu, X., Sheth, N., Yong, L., Callon, R., and D. Black,
              "Encapsulating MPLS in UDP", RFC 7510,
              DOI 10.17487/RFC7510, April 2015,
              <https://www.rfc-editor.org/info/rfc7510>.

   [RFC8077]  Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and
              Maintenance Using the Label Distribution Protocol (LDP)",
              STD 84, RFC 8077, DOI 10.17487/RFC8077, February 2017,
              <https://www.rfc-editor.org/info/rfc8077>.

   [RFC8277]  Rosen, E., "Using BGP to Bind MPLS Labels to Address
              Prefixes", RFC 8277, DOI 10.17487/RFC8277, October 2017,
              <https://www.rfc-editor.org/info/rfc8277>.

   [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>.

Authors' Addresses

   Srihari Sangli
   Juniper Networks Inc.
   Exora Business Park
   Bangalore, KA  560103
   India

   Email: ssangli@juniper.net


   Ron Bonica
   Juniper Networks Inc.
   2251 Corporate Park Drive
   Herndon, Virginia  20171
   USA

   Email: rbonica@juniper.net













Sangli & Bonica          Expires January 6, 2020               [Page 16]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/