IGP Extensions to Support Flex-Algorithm Aware Traffic Engineering
draft-cp-lsr-fa-aware-te-00

Document Type Active Internet-Draft (individual)
Authors Ran Chen  , Shaofu Peng 
Last updated 2021-04-20
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Networking Working Group                                         R. Chen
Internet-Draft                                                   S. Peng
Intended status: Standards Track                         ZTE Corporation
Expires: October 20, 2021                                 April 18, 2021

   IGP Extensions to Support Flex-Algorithm Aware Traffic Engineering
                        draft-cp-lsr-fa-aware-te-00

Abstract

   [I-D.ietf-lsr-flex-algo]proposes a solution that allows IGPs
   themselves to compute constraint based paths over the network, and it
   also specifies a way of using Segment Routing (SR) Prefix-SIDs and
   SRv6 locators to steer packets along the constraint-based paths.

   [RFC8570] describes IS-IS extensions to distribute network-
   performance information (such as residual bandwidth, and available
   bandwidth).

   This draft describes the IGP extensions to advertise the
   corresponding network-performance information of the Flex-Algorithm.

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 October 20, 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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   (https://trustee.ietf.org/license-info) in effect on the date of

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   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
   3.  IS-IS Extensins for FA-TE . . . . . . . . . . . . . . . . . .   3
     3.1.  Maximum Reservable Link Bandwidth per Algorithm Sub-TLV .   3
     3.2.  Available Link Bandwidth per Algorithm Sub-TLV  . . . . .   4
     3.3.  Utilized Link Bandwidth per Algorithm Sub-TLV . . . . . .   5
   4.  OSPF Extensins for FA-TE  . . . . . . . . . . . . . . . . . .   6
   5.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   [I-D.ietf-lsr-flex-algo]proposes a solution that allows IGPs
   themselves to compute constraint based paths over the network, and it
   also specifies a way of using Segment Routing (SR) Prefix-SIDs and
   SRv6 locators to steer packets along the constraint-based paths.

   [RFC8570] describes IS-IS extensions to distribute network-
   performance information (such as link delay, delay variation, packet
   loss, residual bandwidth, and available bandwidth).

   The current Flex-Algorithm technology may support the implementation
   of different QoS (Quality of Service QoS) policies of different
   algorithms (algorithm) at the forwarding plane.  It includes
   different bandwidth, traffic class of service, queue scheduling
   policies (such as low-delay queue, Priority Queuing priority queue)
   and discard policies (such as tail discard and random discard).  This
   is actually the local behavior of the forwarding plane inside a node.
   However, it's not enough.  In order to comprehensively optimize the
   service traffic running in each Flex-Algorithm and avoid unnecessary
   traffic congestion, the relevant path control technology needs to be
   implemented in the control plane.  That is, to manage and maintain
   the bandwidth resource reservation and consumption information for
   each Flex-algo plane, and use the information for path calculation
   and orchestration of the Flex-Algorithm.

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   This draft describes the IGP extensions to advertise the
   corresponding network-performance information of the Flex-Algorithm.

2.  Conventions used in this document

   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.  IS-IS Extensins for FA-TE

   This document registers new IS-IS FA-TE sub-TLVs in the "Sub-TLVs for
   TLVs 22, 23, 141, 222, and 223" registry.  These new sub-TLVs provide
   ways to distribute network-performance information of the Flex-
   Algorithm.

   This document registers several sub-TLVs:

             Type    Description
            ----------------------------------------------------

             TBD     Maximum Reservable Link Bandwidth per Algorithm

             TBD     Available Bandwidth per Algorithm

             TBD     Utilized Bandwidth per Algorithm

3.1.  Maximum Reservable Link Bandwidth per Algorithm Sub-TLV

   This sub-TLV advertises maximum reservable link bandwidth attributes
   on a particular link for a Flex-Algorithm.

   The Maximum Reservable Link Bandwidth per Algorithm Sub-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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Type        |     Length    |   Algorithm   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 Maximum Reservable Link Bandwidth             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 1

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

   Length: 1 octets.

   Algorithm: 1 octets.  Flex-Algorithm number,the value between 128 and
   255 inclusive,the same as the definition of Flex-Algorithm in
   [I-D.ietf-lsr-flex-algo].  Indicates that the value in the Maximum
   Reserved Link Bandwidth field is for a specific Flex-algo plane.

   Maximum Reserved Link Bandwidth: 4 octets.Indicates the maximum link
   bandwidth that can be reserved for a specific FA-algorithm.

   Note that the maximum reserved link bandwidth irrelevant to Flex-algo
   can be classified as MRLB-FA corresponding to algorithm 0.
   Therefore, the Sub-TLV (set the Algorithm field to 0) or the Maximum
   Reservable Link Bandwidth Sub-TLV defined by [RFC5305] can be used.If
   a node receives two types of notifications at the same time, the
   bandwidth value carried in the conventional known Sub-TLV is
   preferred.

3.2.  Available Link Bandwidth per Algorithm Sub-TLV

   This Sub-TLV advertises the available bandwidth on a particular link
   for a specific Flex-Algorithm.

   The Available Link Bandwidth per Algorithm Sub-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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Type        |     Length    |   Algorithm   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Available Link Bandwidth                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 3

   Type: TBD3 (Suggested value to be assigned by IANA)

   Length: 1 octets.

   Algorithm: 1 octets.  Flex-Algorithm number,the value between 128 and
   255 inclusive,the same as the definition of Flex-Algorithm in
   [I-D.ietf-lsr-flex-algo].  Indicates that the value in the Available
   Link Bandwidth field is for a specific Flex-algo plane.

   Available Link Bandwidth: 4 octets.  Indicates the available link
   bandwidth that can be reserved for a specific FA-algorithm.

   Note that the available link bandwidth irrelevant to Flex-algo can be
   classified as ARLB-FA corresponding to algorithm 0.  Therefore, the
   Sub-TLV (set the Algorithm field to 0) or the Unidirectional
   Available Bandwidth Sub-TLV defined by [RFC8570] can be used.If a
   node receives two types of notifications at the same time, the
   bandwidth value carried in the conventional known Sub-TLV is
   preferred.

3.3.  Utilized Link Bandwidth per Algorithm Sub-TLV

   This Sub-TLV advertises the utilized bandwidth on a particular link
   for a specific Flex-Algorithm.

   The Utilized Link Bandwidth per Algorithm Sub-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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Type        |     Length    |   Algorithm   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Utilized Link Bandwidth                   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 4

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

   Length: 1 octets.

   Algorithm: 1 octets.  Flex-Algorithm number,the value between 128 and
   255 inclusive,the same as the definition of Flex-Algorithm in
   [I-D.ietf-lsr-flex-algo].  Indicates that the value in the Utilized
   Link Bandwidth field is for a specific Flex-Algorithm plane.

   Utilized Link Bandwidth: 4 octets.  Indicates the Utilized link
   bandwidth that can be reserved for a specific Flex-Algorithm.

   Note that the Utilized link bandwidth irrelevant to Flex-algo can be
   classified as ULB-FA corresponding to algorithm 0.  Therefore, the
   Sub-TLV (set the Algorithm field to 0) or the Unidirectional Utilized
   Bandwidth Sub-TLV defined by [RFC8570] can be used.If a node receives
   two types of notifications at the same time, the bandwidth value
   carried in the conventional known Sub-TLV is preferred.

4.  OSPF Extensins for FA-TE

   OSPF extensions for FA-TE will be defined in next version.

5.  Examples

   Assume two Flex-Algorithm, FA128 and FA129, with the following
   configuration parameters:

     Per TE link resource allocation:
     Max-BW(interface): 100G (derived from the physical interface BW)
         Max-resv-BW(interface): 100G (default: equal to Max-BW)

     Flex-Algorithm:
     Max-resv-link-BW(FA128): 10G
     Max-resv-link-BW(FA129): 20G

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     Time0: no LSPs
     When the controller is used for path calculation, the controller first collects the network
     topology information through the BGP-LS, which contains the MRLB-FA/ULB-FA/ALB-FA information
     of each link. Static bandwidth reservation information maintained by the controller:
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  TE link    |  Flex-Algorithm |                  Bandwidth                      |
     |-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
     |             |    FA0          | MRLB-FA = 70G | ULB-A = 0 |  ALB-A = 70G        |
     |             |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
     |  Link 1     |    FA128        | MRLB-FA = 10G | ULB-A = 0 |  ALB-A = 10G        |
     |             |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
     |             |    FA129        | MRLB-FA = 20G | ULB-A = 0 |  ALB-A = 20G        |
     +-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|

     Time1: Create a new TE path1 in FA 128 with reserved bandwidth of 5G
     The controller updates the reserved static bandwidth information:
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  TE link    |  Flex-Algorithm |                      Bandwidth                        |
     |-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
     |             |    FA0          |        MRLB-FA = 70G    | ULB-FA = 0|  ALB-FA = 70G   |
     |             |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
     |  Link 1     |    FA128        | MRLB-FA = 10G           | ULB-FA = 0|  ALB-FA = 10G   |
     |             |                 | (TE path1 statically    |           |                 |
     |             |                 |reserve 5G, remaining 5G}|           |                 |
     |             |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|
     |             |    FA129        |     MRLB-FA = 20G       | ULB-FA = 0|  ALB-FA = 20G   |
     +-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Time3: After the TE path1 starts to carry traffic, suppose the service traffic on the TE path1
             runs at full load.The controller updates the reserved static bandwidth information:
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  TE link    |  Flex-Algorithm |                      Bandwidth                          |
     |-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
     |             |    FA0          |        MRLB-FA = 70G    | ULB-FA = 0  |  ALB-FA = 70G   |
     |             |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
     |  Link 1     |    FA128        | MRLB-FA = 10G           | ULB-FA = 5G |  ALB-FA = 5G    |
     |             |                 | (TE path1 statically    |             |                 |
     |             |                 |reserve 5G, remaining 5G}|             |                 |
     |             |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|
     |             |    FA129        |     MRLB-FA = 20G       | ULB-FA = 0  |  ALB-FA = 20G   |
     +-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Now suppose to continue to create another TE path2 in the Flex-algo 128.
     This TE path needs to reserve 6G bandwidth. When the controller is used for path computation,
     path computation will fail, Beacuse there is no link resource that meets the bandwidth requirement.

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6.  IANA Considerations

   IANA maintains the registry for the sub-TLVs.  IANA has registered
   the following sub-TLVs in the "Sub-TLVs for TLVs 22, 23, 141, 222,
   and 223" registry:

             Type    Description
            ----------------------------------------------------

             TBD     Maximum Reservable Link Bandwidth per Algorithm

             TBD     Residual Bandwidth per Algorithm

             TBD     Available Bandwidth per Algorithm

             TBD     Utilized Bandwidth per Algorithm

7.  Security Considerations

   TBD.

8.  Acknowledgements

   TBD.

9.  Normative References

   [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-13 (work in progress), October 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>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305, October
              2008, <https://www.rfc-editor.org/info/rfc5305>.

   [RFC8570]  Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward,
              D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE)
              Metric Extensions", RFC 8570, DOI 10.17487/RFC8570, March
              2019, <https://www.rfc-editor.org/info/rfc8570>.

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Authors' Addresses

   Ran Chen
   ZTE Corporation

   Email: chen.ran@zte.com.cn

   Shaofu Peng
   ZTE Corporation

   Email: peng.shaofu@zte.com.cn

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