Internet DRAFT - draft-chen-idr-bgp-ls-transport-slice

draft-chen-idr-bgp-ls-transport-slice







L                                                                R. chen
Internet-Draft                                                  Sh. Peng
Intended status: Standards Track                         ZTE Corporation
Expires: March 6, 2021                                 September 2, 2020


                 BGP-LS Extensions for Transport Slice
                draft-chen-idr-bgp-ls-transport-slice-02

Abstract

   [I-D.peng-teas-network-slicing] defines a unified TN-slice
   identifier, AII(administrative instance identifier), to indicate the
   topology, computing, storage resources of the dedicated virtual
   network for both intra-domain and inter-domain network slicing
   scenarios.  This draft defines extensions to BGP-LS protocol in order
   to advertise the information of the transport slice.

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 March 6, 2021.

Copyright Notice

   Copyright (c) 2020 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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   include Simplified BSD License text as described in Section 4.e of




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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  BGP-LS Extensions for transport slice . . . . . . . . . . . .   3
     3.1.  Node Attribute TLVs . . . . . . . . . . . . . . . . . . .   3
       3.1.1.  TN-slice identifier Participation TLV . . . . . . . .   3
     3.2.  Link Attribute TLVs . . . . . . . . . . . . . . . . . . .   4
       3.2.1.  TN-slice Identifier list sub-TLV  . . . . . . . . . .   4
       3.2.2.  L2 Bundle Member TN-Slice Identifier TLV  . . . . . .   5
       3.2.3.  Adjacency-SID for TN-slice Identifier TLV . . . . . .   5
       3.2.4.  LAN-Adj-SID for TN-slice Identifier TLV . . . . . . .   6
     3.3.  Prefix Attribute TLVs . . . . . . . . . . . . . . . . . .   7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   For a packet network, network slicing requires the underlying network
   to support partitioning of the network resources to provide the
   client with dedicated (private) networking, computing, and storage
   resources drawn from a shared pool.  [I-D.peng-teas-network-slicing]
   defines a unified TN-slice identifier, AII(administrative instance
   identifier), to indicate the topology, computing, storage resources
   of the dedicated virtual network for both intra-domain and inter-
   domain network slicing scenarios, and how to compute SR-BE or SR-TE
   path according to TN-slice Identifier combined with other criteria.

   [I-D.zch-lsr-isis-network-slicing] defines the IS-IS extensions
   required to distribute TN-slice Identifier(that is AII) information
   in an AS.

   In order to satisfy the need for applications that require
   topological visibility across one area or Autonomous System (AS).
   This document specifies extensions to the BGP Link-state address-
   family in order to advertise TN-slice specific information.  An
   external component (e.g., a controller) then can collect TN-slice
   information in the "northbound" direction.








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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.  BGP-LS Extensions for transport slice

   BGP-LS [RFC7752] defines the link-state NLRI that can be a Node NLRI,
   a Link NLRI or a Prefix NLRI.  The link-state information is mapped
   to BGP link-state NLRI within the BGP-LS Attribute.  In addition,
   [I-D.ietf-idr-bgpls-inter-as-topology-ext] defines Stub Link NLRI
   that is used to describe the inter-as link.  This document adds
   additional BGP-LS Attribute TLVs in order to encode TN-slice
   information.  It does not introduce any changes to the encoding of
   the BGP-LS NLRIs.

3.1.  Node Attribute TLVs

3.1.1.  TN-slice identifier Participation TLV

   The TN-slice identifier Participation TLV is used to advertise which
   TN-slice a router wants to take part in.  It is a new TLV of the
   optional BGP-LS Attribute that is associated with the node NLRI.
   This information is derived from TN-slice identifier Participation
   sub-TLV of IS-IS (section 3 of [I-D.zch-lsr-isis-network-slicing].

   The TN-slice identifier Participation 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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           |            Type=TBD1          |             Length            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     AII for virtual networks 1                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           | ...                                                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     AII for virtual networks N                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


              Figure 1: TN-slice identifier Participation TLV




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   where:

   Type: TBD1 (Suggested value to be assigned by IANA)

   Length: variable.

   AII for VN: allocate different TN-slice identifier (AII) for
   different virtual networks.  AII is used to distinguish different
   virtual network resources.  The node can join to multiple slices at
   the same time.

3.2.  Link Attribute TLVs

   The following Link Attribute TLVs are defined:


                +-------+---------------------------------------------+
                | Type  |            Description                      |
                +-------+---------------------------------------------+
                | TBD2  |   The TN-slice Identifier list TLV          |
                | TBD3  |   L2 Bundle Member TN-Slice Identifier TLV  |
                                | TBD4  |   Adjacency-SID for TN-slice Identifier TLV |
                | TBD5  |   LAN-Adj-SID for TN-slice Identifier TLV   |
                +-------+---------------------------------------------+



                    Table 1:The new Link Attribute TLVs

   These TLVs should only be added to the BGP-LS Attribute associated
   with the Link NLRI or Stub Link NLRI.

3.2.1.  TN-slice Identifier list sub-TLV

   TN-slice Identifier can be used to color links and partition underlay
   resource.  This section is derived from TN-slice Identifier list sub-
   TLV of IS-IS (section 4 of [I-D.zch-lsr-isis-network-slicing].)

   The TN-slice Identifier list TLV 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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            Type=TBD2          |               Length          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     AII for virtual networks 1                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           |    ...                                                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     AII for virtual networks N                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 2

   Type: TBD2 (Suggested value to be assigned by IANA)

   Length: variable.

   AII for VN: allocate different TN-slice identifier (AII) for
   different virtual networks.  AII is used to distinguish different
   virtual network resources.  The link can join to multiple slices at
   the same time.  The link can be configured to an IGP instance, or as
   an inter-as link.

3.2.2.  L2 Bundle Member TN-Slice Identifier TLV

   This TLV is used to advertise TN-slice Identifier for L2 Bundle
   Member associated with a parent L3 adjacency which is Point-to-Point.
   This information is derived from TN-slice Identifier for L2 Bundle
   Member sub-TLV of IS-IS (section 5 of
   [I-D.zch-lsr-isis-network-slicing]).  The following format is defined
   for this sub-TLV:

   Type: TBD3.

   Length: variable

   L2 Bundle Member TN-slice Identifier.There MUST be one TN-slice
   Identifier(AII) for each of the L2 Bundle Members advertised under
   the preceding L2 Bundle Member Attribute Descriptor.  The parrent
   link can be configured to an IGP instance, or as an inter-as link.

3.2.3.  Adjacency-SID for TN-slice Identifier TLV

   This TLV is used to distinguish forwarding behavior of different
   virtual networks, Adjacency-SID need to be allocated per TN-slice
   Identifier.  This information is derived from TN-slice Identifier for




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   Adjacency-SID for TN-slice Identifier sub-TLV of IS-IS (section 7 of
   [I-D.zch-lsr-isis-network-slicing]).

   The following format is defined for this sub-TLV:


       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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |             Type=TBD4         |             Length            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           |     Flags     |    Weight     |           Reserved            |
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                            AII                                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      SID/Index/Label(Variable)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 3

   where:

   Type:TBD4(Suggested value to be assigned by IANA)

   Length: Variable.  Depending on the size of the SID.

   Weight: Variable. 1 octet carrying the weight used for load-balancing
   purposes.  The use of weight is described in section 3.4 of
   [RFC8402].

   AII: Identifies the TN-slice (AII) information corresponding to the
   Adjacency-SID.

   The "Flags" and "SID/Index/Label" fields are the same as the
   Adjacency-SID sub-TLV [RFC8667].

3.2.4.  LAN-Adj-SID for TN-slice Identifier TLV

   In LAN subnetworks, [RFC8667] defines the LAN-Adj-SID sub-TLV for a
   router to advertise the Adj-SID of each of its neighbors.

   LAN-Adj-SID for TN-slice Identifier TLV is used to distinguish
   forwarding behavior of different virtual networks, Adjacency-SID need
   to be allocated per TN-slice Identifier.  This information is derived
   from the LAN-Adj-SID for TN-slice Identifier sub-TLV of IS-IS
   (section 8 of I-D.  [I-D.zch-lsr-isis-network-slicing]).





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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 2
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Type=TBD5             |              Length           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Flags    |    Weight     |           Reserved            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Neighbor System-ID (ID length octets)        |
      +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              AII                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   SID/Label/Index (variable)                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                                 Figure 4

   where:

   Type:TBD5 (Suggested value to be assigned by IANA)

   Length: Variable.  Depending on the size of the SID.

   The "Flags" and "SID/Index/Label" fields are the same as the
   Adjacency-SID sub-TLV [RFC8667].

   AII: Identifies the TN-slice (AII) information corresponding to the
   Adjacency-SID.

3.3.  Prefix Attribute TLVs

   Prefix-SID for TN-slice Identifier TLV should only be added to the
   BGP-LS Attribute associated with the Prefix NLRI describing the
   prefix of the IGP node.  This TLV is used to distinguish forwarding
   behavior of different virtual networks.This information is derived
   from TN-slice identifier Participation sub-TLV of IS-IS (section 6 of
   [I-D.zch-lsr-isis-network-slicing]).

   The Prefix-SID for TN-slice Identifier TLV 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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            Type=TBD6          |             Length            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           |     Flag      |   Algorithm   |         Reserved              |
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                            AII                                |
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      SID/Index/Label(Variable)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 5

   where:

   Type:TBD6 (Suggested value to be assigned by IANA)

   Length: Variable.  Depending on the size of the SID.

   The "Flags" and "SID/Index/Label" fields are the same as the Prefix-
   SID sub-TLV [RFC8667].

   Algorithm: Accoridng to section "3.2.  SR-Algorithm Sub-TLV" of
   [RFC8667], two values can be set in this field.

   o  0: Shortest Path First (SPF) algorithm based on link metric.

   o  1: Strict Shortest Path First (SPF) algorithm based on link
      metric.

   Note that[I-D.ietf-lsr-flex-algo] also allows user to define other
   algorithm values, i.e., FA-id within [128, 255], for the purpose of
   constraint based path computation.  However, an FA-id algorithm value
   MUST not be set in this field, the reason is that FA-id has not
   semantic local within AII.

   AII: Identifies the TN-slice (AII) information corresponding to the
   Prefix-SID.

4.  IANA Considerations

   This document does not define any new protocol or any extension to an
   existing protocol.







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5.  Acknowledgements

   TBD

6.  Normative References

   [I-D.ietf-idr-bgpls-inter-as-topology-ext]
              Wang, A., Chen, H., Talaulikar, K., and S. Zhuang, "BGP-LS
              Extension for Inter-AS Topology Retrieval", draft-ietf-
              idr-bgpls-inter-as-topology-ext-08 (work in progress),
              April 2020.

   [I-D.ietf-lsr-flex-algo]
              Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
              A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex-
              algo-10 (work in progress), August 2020.

   [I-D.peng-teas-network-slicing]
              Peng, S., Chen, R., Mirsky, G., and F. Qin, "Packet
              Network Slicing using Segment Routing", draft-peng-teas-
              network-slicing-03 (work in progress), February 2020.

   [I-D.zch-lsr-isis-network-slicing]
              Zhu, Y., Chen, R., Peng, S., and F. Qin, "IS-IS Extensions
              to Support Transport Network Slices using Segment
              Routing", draft-zch-lsr-isis-network-slicing-05 (work in
              progress), July 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>.

   [RFC4915]  Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
              Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
              RFC 4915, DOI 10.17487/RFC4915, June 2007,
              <https://www.rfc-editor.org/info/rfc4915>.

   [RFC5120]  Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
              Topology (MT) Routing in Intermediate System to
              Intermediate Systems (IS-ISs)", RFC 5120,
              DOI 10.17487/RFC5120, February 2008,
              <https://www.rfc-editor.org/info/rfc5120>.

   [RFC5340]  Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
              <https://www.rfc-editor.org/info/rfc5340>.




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   [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
              S. Ray, "North-Bound Distribution of Link-State and
              Traffic Engineering (TE) Information Using BGP", RFC 7752,
              DOI 10.17487/RFC7752, March 2016,
              <https://www.rfc-editor.org/info/rfc7752>.

   [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>.

   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

   [RFC8667]  Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
              Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
              Extensions for Segment Routing", RFC 8667,
              DOI 10.17487/RFC8667, December 2019,
              <https://www.rfc-editor.org/info/rfc8667>.

Authors' Addresses

   Ran Chen
   ZTE Corporation
   No.50 Software Avenue, Yuhuatai District
   Nanjing
   China

   Email: chen.ran@zte.com.cn


   Shaofu
   ZTE Corporation
   No.68 Zijinghua Road, Yuhuatai District
   Nanjing
   China

   Email: peng.shaofu@zte.com.cn












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