RIFT Working Group                                             W. Cheng
Internet Draft                                             China Mobile
Intended status: Standards Track                                 C. Lin
Expires: September 03, 2025                        New H3C Technologies
                                                                R. Wang
                                                           China Mobile
                                                          March 3, 2025


                         RIFT extensions for SRv6
                    draft-cheng-rift-srv6-extensions-04


Abstract

   The Segment Routing (SR) architecture allows a flexible definition
   of the end-to-end path by encoding it as a sequence of topological
   elements called segments.  It can be implemented over an MPLS or
   IPv6 data plane.  This document describes the RIFT extensions
   required to support Segment Routing over the IPv6 data plane (SRv6).

Status of this Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on September 03 2025.

Copyright Notice

   Copyright (c) 2025 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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   document must include Simplified BSD License text as described in

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   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. SRv6 KV TIE....................................................3
   3. SRV6 Locator TIE...............................................8
   4. Advertise End.X SID in Node Neighbor...........................9
   5. Example.......................................................10
   6. Security Considerations.......................................12
   7. IANA Considerations...........................................12
      7.1. SRv6 Locator KV TIE......................................12
      7.2. SRv6 Locator TIE.........................................13
      7.3. SRv6 End.X SID...........................................13
   8. References....................................................14
      8.1. Normative References.....................................14
   Appendix A.  Thrift Models.......................................15
      A.1.  common.thrift ..........................................15
      A.2.  encoding.thrift ........................................16
      A.3.  common_srv6.thrift......................................17
   Authors' Addresses...............................................19

1. Introduction

   The Segment Routing (SR) architecture [RFC8402] specifies how a node
   can steer a packet using an ordered list of instructions, called
   segments.  These segments are identified using Segment Identifiers
   (SIDs).

   Segment Routing can be instantiated on the IPv6 data plane through
   the use of the Segment Routing Header (SRH) defined in
   [RFC8754].Segment Routing instantiation on the IPv6 dataplane is
   referred to as SRv6.

   The network programming paradigm for SRv6 is specified in
   [RFC8986].It describes how any behavior can be bound to a SID and
   how any network program can be expressed as a combination of SIDs.
   It also describes several well-known behaviors that can be bound to
   SRv6 SIDs.

   Using SRv6 in data center networks brings several advantages:

   1) Improved Scalability: SRv6 simplifies the network architecture by
      reducing the amount of state that must be maintained in network
      devices, which leads to increased scale and reduced management
      overhead.

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   2) Traffic Engineering: SRv6 enables more granular control over
      traffic paths within the network, allowing operators to direct
      traffic along specific paths to better utilize network resources
      and reduce congestion.

   3) Service Function Chaining: With SRv6, network operators can
      easily define paths that traverse multiple service functions,
      including firewalls, load balancers and other middleboxes. This
      enables the creation of more flexible and scalable service chains
      to support a wide range of applications.

   4) Path Segment Identification: SRv6 allows for the identification
      of specific path segments within the network, making
      troubleshooting and fault isolation simpler and faster.

   5) Simplified Tunneling: SRv6 supports tunneling for traffic across
      an IPv6 network without the need for an IP-in-IP or GRE
      encapsulation. This simplifies the network architecture and
      reduces complexity.

   This document describes the RIFT extensions required to support
   Segment Routing over the IPv6 data plane (SRv6).

   At a high level, the extensions to RIFT are comprised of the
   following:

   1) Add new SRv6 KV TIE using Well-Known KV TIE that is used to
      advertise an SRv6 Locator, its attributes, and SIDs.

   2) Add new SRv6 Locator TIE, which is used to advertise Locator
      information southbound and northbound, as well as End SID
      information.

   3) In the neighbor information of Node TIE, Add the new End.X SID
      information in the neighbor information of Node TIE to advertise
      the corresponding connection of End.X.



2. SRv6 KV TIE

   For RIFT network, Each node is provisioned with a Locator. The
   Locator address are communicated to each node out-of-band and stored
   as configuration information.  Communication could be done via
   primitive pen and paper or via modern signaling (Netconf/YANG) from
   a configuration management system. Then the node can use his own
   locator address to generate End-SID, End.X-SID etc.


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   To support Zero Touch Provisioning (ZTP), we can define a flexible
   Key-Value (K-V) format for transmitting SRv6 information such as
   SRv6 Locator information in RIFT SRv6 network, in order to enable
   TOF to pass the Locator address information to all nodes via KV-TIE.
   In this way, TOF can package the Locator address information into
   KV-TIE and transmit it to all nodes in the SRv6 network to support
   Zero Touch Provisioning. With this approach, all nodes in the
   network can obtain the Locator address information and use the
   addresses for path programming and other operations in the SRv6
   network.

   This section requests an entry from the RIFT Well-Known Key-Type
   Registry for networks that use SRv6 along with suggested values
   inaccordance with RIFT-KV-REGISTRY [RIFT-KV-REGISTRY].


   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Type             |   Key-Len     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             "SRv6 Locator" + AdvSystemID + SystemID           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             SRv6 Locator Entry                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             SRv6 End.X Entry                                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 1: SRv6 Locator Key/Value Pair

   where:

    Type: SRv6, TBD.

       "SRv6 Locator": indicate that this is a Locator KV TIE.
       AdvSystemID: The Advertiser's 64-bit RIFT System ID. Typically,
                 only the TOF publishes SRv6 KV TIEs, using its
                 SystemID as the AdvSystemID.
       System ID: A node's 64-bit RIFT System ID.
       SRv6 Locator Entry: A node's SRv6 Locator Entry.

   The SRv6 Locator Entry has the following format:





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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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Metric                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Loc Size     |                    Resv                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   //              Locator (continued, variable)                  //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Sub-TLVs (variable) . . .             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                        Figure 2: SRv6 Locator Entry


   o Metric:  4 octets, as described in Section 4 of [RFC5305].

   o Loc-Size:  1 octet.  Number of bits in the SRv6 Locator field,
      which  MUST be from the range (1-128).  The entire TLV MUST
      beignored If the Loc-Size is outside this range.

   o Resv: 3 octets, Not defined.

   o Locator:  1-16 octets.  This field encodes the advertised SRv6
      Locator.  The SRv6 Locator is encoded in the minimal number of
      octets for the given number of bits.  Trailing bits MUST be set
      to zero and ignored when received.
   o Optional Sub-TLVs: The SRv6 SID LBLN Information and SRv6 End SID
      Entry SHOULD be included in the Locator Entry.


   The SRv6 SID Structure Sub-Sub-TLV has the following format:

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    LB Length  |  LN Length    | Fun. Length   |  Arg. Length  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    Figure 3: SRv6 SID LBLN Information

   Where:





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           LB Length: 1-octet field.  SRv6 SID Locator Block length in
                 bits.
           LN Length: 1-octet bit field.  SRv6 SID Locator Node length
                 in bits.
           Function Length: 1-octet field.  SRv6 SID Function length in
                 bits.
           Argument Length: 1-octet field.  SRv6 SID Argument length in
                 bits.


   The SRv6 End SID Entry has the following format:


   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Endpoint Behavior       |      Flags                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | SID (128 bits) . . .                                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | SID (cont . . .)                                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | SID (cont . . .)                                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | SID (cont . . .)                                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    Figure 4: SRv6 End SID Entry

   where:

   o Flags:  2 octet.  No flags are currently defined.  All bits are
      reserved for future use.  They MUST be set to zero on
      transmission and MUST be ignored on receipt.

   o Endpoint Behavior:  2 octets, as defined in [RFC8986].

   o SID:  16 octets.  This field encodes the advertised SRv6 SID.



   The SRv6 End.X SID Entry has the following format:







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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         link id                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         End.X SID                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                        Figure 5: SRv6 End.X Entry in SRv6 Locator KV TIE


struct Srv6EndXSidElement {
   1: required common.LinkIDPair link_id,
   2: required Srv6SidElement srv6_endx_sid,
}

   The Format of End.X SID:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Flags       |   Algorithm   |   Weight      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Endpoint Behavior      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | SID (128 bits) . . .                                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | SID (cont . . .)                                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | SID (cont . . .)                                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | SID (cont . . .)                                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | SRv6 SID LBLN Information (optional)                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    Figure 6: Format of End.X SID
     where:

         Flags:  1 octet.

          0 1 2 3 4 5 6 7
         +-+-+-+-+-+-+-+-+
         |B|S|P|Reserved |
         +-+-+-+-+-+-+-+-+


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     where:

         B-Flag:  Backup flag.  If set, the SID is eligible for
                 protection, e.g., using IP Fast Reroute (IPFRR)
                 [RFC5286] as described in [RFC8355].
         S-Flag:  Set flag.  When set, the S-flag indicates that the
                 SID refers to a set of adjacencies (and therefore MAY
                 be assigned to other adjacencies as well).
         P-Flag:  Persistent flag.  When set, the P-flag indicates that
                 the SID is persistently allocated, i.e., the SID value
                 remains consistent across router restart and/or
                 interface            flap.
         Reserved bits:  Reserved bits MUST be zero when originated and
                 MUST be ignored when received.
         Algorithm:  1 octet, as defined in the "IGP Algorithm Types"
                 registry [RFC8665].
         Weight:  1 octet.  The value represents the weight of the SID
                 for the purpose of load balancing.  The use of the
                 weight is defined in [RFC8402].
         Endpoint Behavior:  2 octets, as defined in [RFC8986].
         SID:  16 octets.  This field encodes the advertised SRv6 SID.
         SRv6 SID LBLN Information: describe SRv6 SID LBLN Information.


3. SRV6 Locator TIE

   In the RIFT network, in order to support SRv6, SRv6 Locator need to
   be distributed in SRv6 Locator TIEs.

   The Locator address and End-SID advertised in SRv6 Locator TIE.

   When a neighbor node receives a Locator Address Advertisement in
   SRv6 Locator TIE, it adds a route for the Locator address to its
   routing table.

   The format of the SRv6 Locator TLV is the same as the SRv6 Locator
   TLV in SRv6 KV TIE described in Section 2 of this document.

   When supporting the compression mode, the SRv6 SID LBLN Information
   needs to be carried in the End-SID information. The format of SRv6
   SID LBLN Information is described in Figure 3.

      +===================================+=====+=======+===========+
      |Name                               |Value| Schema|Description|
      |                                   |     |Version|           |
      +===================================+=====+=======+===========+
      |Illegal                            |    0|    6.1|           |

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      +-----------------------------------+-----+-------+-----------+
      |TIETypeMinValue                    |    1|    6.1|           |
      +-----------------------------------+-----+-------+-----------+
      |NodeTIEType                        |    2|    6.1|           |
      +-----------------------------------+-----+-------+-----------+
      |PrefixTIEType                      |    3|    6.1|           |
      +-----------------------------------+-----+-------+-----------+
      |...                                                          |
      +-----------------------------------+-----+-------+-----------+
      |LocatorTIEType                     | TBD |   6.1 |This Document|
      +-----------------------------------+-----+-------+------------+


   /** Description of a Locator TIE. */

   struct LocatorTIEElement {

      /* SRv6 Locator information */

      1: common_srv6.SRv6Locator srv6_locator;

   }

4. Advertise End.X SID in Node Neighbor

   End.X SID is advertised via Node Neighbor in Node TIE, where the
   Neighbor information is extended in the Expanded Neighbor section.

   In Registry RIFT_v6/encoding/NodeNeighborsTIEElement:

      +=========+======+=========+====================================+
      | Name    |Value |  Schema | Description                        |
      |         |      | Version |                                    |
      +=========+======+=========+====================================+
      | level   |    1 |     6.1 | Level of neighbor                  |
      +---------+------+---------+------------------------------------+
      | cost    |    3 |     6.1 | Cost to neighbor.  Ignore anything |
      |         |      |         | larger than `infinite_distance`    |
      |         |      |         | and `invalid_distance`             |
      +---------+------+---------+------------------------------------+
      |link_ids |    4 |     6.1 | Can carry description of multiple  |
      |         |      |         | parallel links in a TIE            |
      +---------+------+---------+------------------------------------+
      |bandwidth|    5 |     6.1 | Total bandwith to neighbor as sum  |
      |         |      |         | of all parallel links              |
      +---------+------+---------+------------------------------------+
      | End.X   |  TBD |     6.1 | SRv6 End.X SID                     |
      +---------+------+---------+------------------------------------+

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                Table 2: Requested Neighbors TIE Element



   The format of End.X SID is as Figure 6 described.

5. Example

   In a RIFT network, SRv6 is used to enable path computation and
   traffic engineering. The RIFT control plane uses SRv6 Segment
   Routing to program paths through the network. Each node in the
   network is assigned a unique IPv6 SID, which is used to represent
   the node and its attached topology. When a source node wants to send
   traffic to a destination node, it simply specifies a list of SIDs
   that correspond to the nodes that the traffic must traverse.
   Intermediate nodes forward the traffic based on the specified SIDs,
   ensuring that it follows the desired path. SRv6 is used in
   conjunction with RIFT's Topology Information Base (TIB) to enable
   efficient path computation and fast rerouting in the event of a
   topology change. With SRv6, RIFT networks can support end-to-end
   traffic engineering, service chaining, and other advanced network
   functions, while also providing fast and efficient routing within
   the network.



   Assuming the Locator Block is 2001:0db8::/32, denoted as LB; ToF1's
   Locator is 2001:0db8:1::/64, denoted as LB:1::/64, NodeSid is
   2001:0db8:1::1, denoted as LB:1::1; other nodes follow the similar
   pattern.


















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             +----------------+      +----------------+     Level 2
             |ToF 1           |      |ToF 2           |
             |NodeSid: LB:1:: |      |NodeSid: LB:2:: |
             |Loc: LB:1::/64  |      |Loc: LB:2::/64  |
             +---+--+--+--+---+      +-+--+---+--+--+--+
                 |  |  |  |            |  |   |  |
                 |  |  |  |            |  |   |  |
                 |  |  |  |            |  |   |  |
     +-----------+  |  +--)------------)--)-+ |  +------------+
     |              |     |            |  | | |               |
     |    +---------)-----)------------+  | | |               |
     |    |         |     |               | | |               |
     |    |         |     +-----------------)-- -----------+  |
     |    |         |                     | | |            |  |
     |    |         +--+     +------------+ | |            |  |
     |    |            |     |              | |  Level 1   |  |
   +-+----+-----+  +---+-----+---+  +-------+-+--+  +------+--+--+
   |Spin11      |  |Spin12       |  |Spin21      |  |Spin22      |
   |NodeSid:    |  |NodeSid:     |  |NodeSid:    |  |NodeSid:    |
   |  LB:3::    |  |   LB:4::    |  |     LB:5:: |  |    LB:6::  |
   |Loc:        |  |Loc:         |  |Loc:        |  |Loc:        |
   |  LB:3::/64 |  |   LB:4::/64 |  |   LB:5::/64|  |   LB:6::/64|
   +--+---+-----+  +---+-----+---+  +--+---+-----+  +---+-----+--+
      |   |            |      |        |   |            |       |
      |   +------------)-+    |        |   +------------)-+     |
      |                | |    |        |                | |     |
      |   +------------+ |    |        |    +-----------+ |     |
      |   |         |    |    |        |    |    Level 0  |     |
   +--+---+-----+   +----+----+--+   +-+----+-----+   +---+-----+----+
   |Leaf11      |   |Leaf12      |   |Leaf21      |   |Leaf22        |
   |NodeSid:    |   |NodeSid:    |   |NodeSid:    |   |NodeSid:      |
   |   LB:7::   |   |   LB:8::   |   |     LB:9:: |   |     LB:A::   |
   |Loc:        |   |Loc:        |   |Loc:        |   |Loc:          |
       LB:7::/64|   |   LB:8::/64|   |  LB:9::/64 |   |    LB:A::/64 |
   +--+---------+   +-+----------+   +-+----------+   ++--------------+
      +               +                +               +
      Prefix11          Prefix12           Prefix21          Prefix22

                      Figure 6: SRv6 information in RIFT network

   During network initialization, the controller distributes all SRv6
   Locator configurations to ToF. Then ToF generates SRv6 KV TIE for
   SRV6 Locator and extends it to all nodes by ZTP. After receiving
   this information, each node generates its own SRv6 Locator
   configurations.


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   Each node generates its Node SID based on its own SRv6 Locator and
   advertise its SRv6 Locator and Node SID information through Node
   TIE.

   After establishing neighbor relationships with other adjacent nodes,
   the node uses the SRv6 Locator information to generate End.X SID and
   carries it in the Neighbors information of Node TIE to be
   transmitted out.

   Assuming Leaf11 sends a packet to Leaf21, when congestion occurs on
   the westward link of TOF1, the controller can specify the packet
   path NodeSid_Spin12, NodeSid_TOF2, NodeSid_Spin21, NodeSid_Leaf21,
   for Leaf11, Leaf11 add an SRv6 header with a Segment List of (SA,DA)
   (2001:0db8:9::, 2001:0db8:5::, 2001:0db8:2::, 2001:0db8:4::, SL=3),
   so that the packet will pass through Leaf11, Spin12, ToF2, Spin21,
   Leaf21 node in order.

   When compression mode is supported, it is not necessary to add the
   SRv6 header, and route can be arranged through the destination
   address. In the path mentioned above, using compression mode, the
   destination address is 2001:0db8:0004:0002:0005:0009:0000:0000 The
   destination address generated through this compression method is
   called C-SID.

   When there are multiple paths available, Controller can select a
   specific path by specifying the End.X SID.

6. Security Considerations

   TBD.

7. IANA Considerations

7.1. SRv6 Locator KV TIE

This document requests an entry from the RIFT Key-Types Registry for
Locator KV TIE in accordance with "RIFT Key-Types" registry [RIFT-KV-
REGISTRY]
   +=======+==============+=============================+===========+
   | Value | Key-Type     | Description                 | Status/   |
   |       |              |                             | Reference |
   +=======+==============+=============================+===========+
   | 0     | Illegal      | Not allowed.                |           |
   +-------+--------------+-----------------------------+-----------+
   | 1     | Experimental | Indicates that the Key-Type |           |
   |       |              | is Experimental.            |           |

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   +-------+--------------+-----------------------------+-----------+
   | 2     | Well-Known   | Indicates that the Key-Type |           |
   |       |              | is Well-Known.              |           |
   +-------+--------------+-----------------------------+-----------+
   | 3     | OUI          | Indicates that the Key-Type |           |
   |       |              | is OUI (vendor specific).   |           |
   +-------+--------------+-----------------------------+-----------+
   | TBD   | SRv6         | Indicates that the Key-Type |This       |
   |       |              | is SRv6.                    |document   |
   +-------+--------------+-----------------------------+-----------+

                Table 3: Requested Key-Type

SRv6-Entry-Type in RIFT SRv6-Locator-Entry:
   +==============+=======+================+=============+
   | Name         | Value | Schema Version | Description |
   +==============+=======+================+=============+
   |SRv6Locator   |     1 |            6.1 |This Document|
   +--------------+-------+----------------+-------------+
   |End.X         |     2 |            6.1 |This Document|
   +--------------+-------+----------------+-------------+

7.2. SRv6 Locator TIE

   This document makes the following registration in the "
   RIFT/common/TIETypeType" registry:

   +=============+=======+================+=============+
   | Name        | Value | Schema Version | Description |
   +=============+=======+================+=============+
   | srv6_locator|   TBD |            8.0 |This document|
   +-------------+-------+----------------+-------------+

              Table 3: IANA Requested srv6 locator TIE


7.3. SRv6 End.X SID

   This document makes the following registration in
   the"NodeNeighborsTIEElement" registry of a Node TIE:

            +=======+=============================================+
            | Value | Name                                        |

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            +=======+=============================================+
            | TBD   | SRv6 End.X SID                              |
            +-------+---------------------------------------------+
              Table 4: IANA Requested Neighbours TIE Element



8. References

8.1. Normative References

   [draft-ietf-rift-sr] Z. Zhang,"SRIFT: Segment Routing in Fat Trees",
             12 January 2023,<https://www.ietf.org/archive/id/draft-
             ietf-rift-sr-00.txt>.

   [draft-ietf-rift-rift] A. Przygienda, Ed., "RIFT: Routing in Fat
             Trees", 14 September 2023,
             <https://www.ietf.org/archive/id/draft-ietf-rift-rift-
             17.txt>

   [RFC8665], P. Psenak, Ed., "OSPF Extensions for Segment Routing",
             December 2019, <https://datatracker.ietf.org/doc/rfc8665>

   [RFC8402], C. Filsfils, Ed., "Segment Routing Architecture", July
             2018, <https://datatracker.ietf.org/doc/rfc8402/>

   [RFC8754], C. Filsfils, Ed., "IPv6 Segment Routing Header (SRH)",
             March 2020, <https://datatracker.ietf.org/doc/rfc8754/>

   [RFC8986], C. Filsfils, Ed., "Segment Routing over IPv6 (SRv6)
             Network Programming", February 2021,
             <https://datatracker.ietf.org/doc/rfc8986/>

   [RFC5305], T. Li., "SIS-IS Extensions for Traffic Engineering",
             October 2008, <https://datatracker.ietf.org/doc/rfc5305/>

   [RFC5286], A. Atlas, Ed., "Basic Specification for IP Fast Reroute:
             Loop-Free Alternates", September 2008,
             <https://datatracker.ietf.org/doc/rfc5286/>

   [RFC8355], C. Filsfils, Ed., "Resiliency Use Cases in Source Packet
             Routing in Networking (SPRING) Networks", March 2018,
             <https://datatracker.ietf.org/doc/rfc8355/>

   [draft-ietf-lsr-ospfv3-srv6-extensions], Z. Li, "OSPFv3 Extensions
             for SRv6", 8 June 2023, <
             https://datatracker.ietf.org/doc/draft-ietf-lsr-ospfv3-
             srv6-extensions/ >

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   Appendix A.  Thrift Models

   This section contains the normative Thrift models required to
   support SRv6. Per the main RIFT [RIFT] specification, all signed
   values MUST be interpreted as unsigned values.

   A.1.  common.thrift

   This section specifies extensions to RIFT common.thrift model.

   These extensions are REQUIRED in order to support SRv6.

   TBD.

   /** Type of TIE.

   */

   enum TIETypeType {


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       Illegal                                     = 0,

       TIETypeMinValue                             = 1,

       /** first legal value */

       NodeTIEType                                 = 2,

       PrefixTIEType                               = 3,

       PositiveDisaggregationPrefixTIEType         = 4,

       NegativeDisaggregationPrefixTIEType         = 5,

       PGPrefixTIEType                             = 6,

       KeyValueTIEType                             = 7,

       ExternalPrefixTIEType                       = 8,

       PositiveExternalDisaggregationPrefixTIEType = 9,

       Srv6LocatorTIEType                          = TBD,

       TIETypeMaxValue                             = TBD+1,

   }



   enum   KVTypes {

       Experimental = 1,

       WellKnown    = 2,

       OUI          = 3,

       Srv6         = TBD,

   }

   A.2.  encoding.thrift

   This section specifies extensions to RIFT encoding.thrift model.

   These extensions are REQUIRED in order to support SRv6.


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   /** Description of a Locator TIE. */

   struct LocatorTIEElement {

      1: SRv6Locator srv6_locator;

   }

/* neighbor of a node */
struct  NodeNeihborsTIEElement {
   ...

   /* endx sid of neighbor */

   6: optional common_srv6.Srv6SidElement endx,

}





   A.3.  common_srv6.thrift

Struct Srv6LBLNElement {
    1: required i8 lb_len,
    2: required i8 ln_len,
    3: required i8 func_len,
    4: required i8 arg_len,
}

struct Srv6SidElement {
   1: required i16 endpoint_behavior,
   2: required i16 flags,
   3: required common.Ipv6Addr sid_addr,
   4: optional Srv6LBLNElement lbln_attrib,


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}

struct Srv6LocatorSubElement {
    /** metric */
    1: required   i32 metric,
    /** loc size*/
    2: require    i8  loc_size,
    /* locator address */
    3: required common.Ipv6Addr locator_addr,
}

struct SRv6LocatorSubTlv {
    /** locator */
    1: required   Srv6LocatorSubElement       srv6_locator,
    /*  lbln information of locator*/
    2: optional   Srv6LBLNElement             locator_lbln,
    /* node sid */
    3: optional   list<Srv6SidElement>     srv6_sid_list,
}

struct Srv6EndXSidElement {
   1: required common.LinkIDPair link_id,
   2: required Srv6SidElement srv6_endx_sid,
}

struct SRv6Locator {
    /* locator info */
    1: required   SRv6LocatorSubTlv            srv6_locator,
    2: optional   list<Srv6EndXSidElement> srv6_endx_sid_list,
}




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Authors' Addresses

   Weiqiang Cheng
   China Mobile
   China

   Email: chengweiqiang@chinamobile.com

   Changwang Lin
   New H3C Technologies
   China

   Email: linchangwang.04414@h3c.com


   Ruixue Wang
   China Mobile
   China

   Email: wangruixue@chinamobile.com




























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