RSVP-TE Extensions for Collecting SRLG Information
draft-ietf-ccamp-rsvp-te-srlg-collect-06

Network Working Group                                      F. Zhang, Ed.
Internet-Draft                                                    Huawei
Intended status: Standards Track                O. Gonzalez de Dios, Ed.
Expires: February 1, 2015                          Telefonica Global CTO
                                                                   D. Li
                                                                  Huawei
                                                             C. Margaria

                                                              M. Hartley
                                                                  Z. Ali
                                                                   Cisco
                                                           July 31, 2014

           RSVP-TE Extensions for Collecting SRLG Information
                draft-ietf-ccamp-rsvp-te-srlg-collect-06

Abstract

   This document provides extensions for the Resource ReserVation
   Protocol-Traffic Engineering (RSVP-TE) to support automatic
   collection of Shared Risk Link Group (SRLG) Information for the TE
   link formed by a LSP.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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Copyright Notice

   Copyright (c) 2014 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

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   (http://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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  RSVP-TE Requirements  . . . . . . . . . . . . . . . . . . . .   3
     3.1.  SRLG Collection Indication  . . . . . . . . . . . . . . .   3
     3.2.  SRLG Collection . . . . . . . . . . . . . . . . . . . . .   3
     3.3.  SRLG Update . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Encodings . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  SRLG Collection Flag  . . . . . . . . . . . . . . . . . .   3
     4.2.  SRLG sub-object . . . . . . . . . . . . . . . . . . . . .   4
   5.  Signaling Procedures  . . . . . . . . . . . . . . . . . . . .   5
     5.1.  SRLG Collection . . . . . . . . . . . . . . . . . . . . .   5
     5.2.  SRLG Update . . . . . . . . . . . . . . . . . . . . . . .   7
     5.3.  Compatibility . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Manageability Considerations  . . . . . . . . . . . . . . . .   7
     6.1.  Policy Configuration  . . . . . . . . . . . . . . . . . .   7
     6.2.  Coherent SRLG IDs . . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  RSVP Attribute Bit Flags  . . . . . . . . . . . . . . . .   8
     8.2.  ROUTE_RECORD Object . . . . . . . . . . . . . . . . . . .   8
     8.3.  Policy Control Failure Error subcodes . . . . . . . . . .   9
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   It is important to understand which TE links in the network might be
   at risk from the same failures.  In this sense, a set of links may
   constitute a 'shared risk link group' (SRLG) if they share a resource
   whose failure may affect all links in the set [RFC4202].

   On the other hand, as described in [RFC4206] and [RFC6107], H-LSP
   (Hierarchical LSP) or S-LSP (stitched LSP) can be used for carrying
   one or more other LSPs.  Both of the H-LSP and S-LSP can be formed as

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   a TE link.  In such cases, it is important to know the SRLG
   information of the LSPs that will be used to carry further LSPs.

   This document provides an automatic mechanism to collect the SRLG for
   the TE link formed by a LSP.  Note that how to use the collected SRLG
   information is out of scope of this document

2.  Requirements Language

   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 RFC 2119 [RFC2119].

3.  RSVP-TE Requirements

3.1.  SRLG Collection Indication

   The ingress nodes of the LSP must be capable of indicating whether
   the SRLG information of the LSP should be collected during the
   signaling procedure of setting up an LSP.  SRLG information SHOULD
   NOT be collected without an explicit request for it being made by the
   ingress node.

3.2.  SRLG Collection

   If requested, the SRLG information should be collected during the
   setup of an LSP.  The endpoints of the LSP may use the collected SRLG
   information and use it for routing, sharing and TE link configuration
   purposes.

3.3.  SRLG Update

   When the SRLG information of an existing LSP for which SRLG
   information was collected during signaling changes, the relevant
   nodes of the LSP must be capable of updating the SRLG information of
   the LSP.  This means that that the signaling procedure must be
   capable of updating the new SRLG information.

4.  Encodings

4.1.  SRLG Collection Flag

   In order to indicate nodes that SRLG collection is desired, this
   document defines a new flag in the Attribute Flags TLV, which is
   carried in an LSP_REQUIRED_ATTRIBUTES or LSP_ATTRIBUTE Object:

   o  Bit Number (to be assigned by IANA, recommended bit 12): SRLG
      Collection flag

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   The SRLG Collection flag is meaningful on a Path message.  If the
   SRLG Collection flag is set to 1, it means that the SRLG information
   should be reported to the ingress and egress node along the setup of
   the LSP.

   The rules of the processing of the Attribute Flags TLV are not
   changed.

4.2.  SRLG sub-object

   This document defines a new RRO sub-object (ROUTE_RECORD sub-object)
   to record the SRLG information of the LSP.  Its format is modeled on
   the RRO sub-objects defined in RFC 3209 [RFC3209].

       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    |            Reserved           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 SRLG ID 1 (4 bytes)                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                           ......                              ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 SRLG ID n (4 bytes)                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

   The type of the sub-object, to be assigned by IANA, which is
   recommended 34.

   Length

   The Length field contains the total length of the sub-object in
   bytes, including the Type and Length fields.  The Length depends on
   the number of SRLG IDs.

   Reserved

   This 2 byte field is reserved.  It SHOULD be set to zero on
   transmission and MUST be ignored on receipt.

   SRLG ID

   This 4 byte field contains one SRLG ID.  There is one SRLG ID field
   per SRLG collected.

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   As described in RFC 3209 [RFC3209], the RECORD_ROUTE object is
   managed as a stack.  The SRLG sub-object SHOULD be pushed by the node
   before the node IP address or link identifier.  The SRLG-sub-object
   SHOULD be pushed after the Attribute subobject, if present, and after
   the LABEL subobject, if requested.

   A node MUST NOT push a SRLG subobject in the RECORD_ROUTE without
   also pushing a IPv4, IPv6 or Unnumbered Interface ID sub-object.

   The rules of the processing of the LSP_REQUIRED_ATTRIBUTES,
   LSP_ATTRIBUTE and ROUTE_RECORD Objects are not changed.

5.  Signaling Procedures

5.1.  SRLG Collection

   Per RFC 3209 [RFC3209], an ingress node initiates the recording of
   the route information of an LSP by adding a RRO to a Path message.
   If an ingress node also desires SRLG recording, it MUST set the SRLG
   Collection Flag in the Attribute Flags TLV which MAY be carried
   either in an LSP_REQUIRED_ATTRIBUTES Object when the collection is
   mandatory, or in an LSP_ATTRIBUTES Object when the collection is
   desired, but not mandatory

   When a node receives a Path message which carries an
   LSP_REQUIRED_ATTRIBUTES Object and the SRLG Collection Flag set, if
   local policy determines that the SRLG information is not to be
   provided to the endpoints, it MUST return a PathErr message with
   Error Code 2 (policy) and Error subcode "SRLG Recording Rejected"
   (value to be assigned by IANA, suggest value 108) to reject the Path
   message.

   When a node receives a Path message which carries an LSP_ATTRIBUTES
   Object and the SRLG Collection Flag set, if local policy determines
   that the SRLG information is not to be provided to the endpoints, the
   Path message SHOULD NOT be rejected due to SRLG recording restriction
   and the Path message SHOULD be forwarded without any SRLG sub-
   object(s) in the RRO of the corresponding outgoing Path message.

   If local policy permits the recording of the SRLG information, the
   processing node SHOULD add local SRLG information, as defined below,
   to the RRO of the corresponding outgoing Path message.  It then
   forwards the Path message to the next node in the downstream
   direction.

   Following the steps described above, the intermediate nodes of the
   LSP can collect the SRLG information in the RRO during the processing

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   of the Path message hop by hop.  When the Path message arrives at the
   egress node, the egress node receives SRLG information in the RRO.

   Per RFC 3209 [RFC3209], when issuing a Resv message for a Path
   message which contains an RRO, an egress node initiates the RRO
   process by adding an RRO to the outgoing Resv message.  The
   processing for RROs contained in Resv messages then mirrors that of
   the Path messages.

   When a node receives a Resv message for an LSP for which SRLG
   Collection is specified, if local policy determines that the SRLG
   information is not to be provided to the endpoints, if the SRLG-
   recording request was in a LSP_REQUIRED_ATTRIBUTES object, then a
   ResvErr with Error code 2 (policy) and Error subcode "SRLG Recording
   Rejected" (value to be assigned by IANA, suggest value 108) MUST be
   sent.  If the request was in a LSP_ATTRIBUTES object, then a ResvErr
   SHOULD NOT be generated, but SRLG information MUST NOT be added in
   the RRO.  When local policy allows recording SRLG information, the
   node SHOULD add SRLG information, as defined below, to the RRO of the
   corresponding outgoing Resv message.  When the Resv message arrives
   at the ingress node, the ingress node can get the SRLG information
   from the RRO in the same way as the egress node.

   Note that a link's SRLG information for the upstream direction cannot
   be assumed to be the same as that in the downstream.

   o  For Path and Resv messages for a unidirectional LSP, a node SHOULD
      include SRLG sub-objects in the RRO for the downstream data link
      only.

   o  For Path and Resv messages for a bidirectional LSP, a node SHOULD
      include SRLG sub-objects in the RRO for both the upstream data
      link and the downstream data link from the local node.  In this
      case, the node MUST include the information in the same order for
      both Path messages and Resv messages.  That is, the SRLG sub-
      object for the upstream link is added to the RRO before the SRLG
      sub-object for the downstream link.

   Based on the above procedure, the endpoints can get the SRLG
   information automatically.  Then the endpoints can for instance
   advertise it as a TE link to the routing instance based on the
   procedure described in [RFC6107] and configure the SRLG information
   of the FA automatically.

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5.2.  SRLG Update

   When the SRLG information of a link is changed, the LSPs using that
   link should be aware of the changes.  The procedures defined in
   Section 4.4.3 of RFC 3209 [RFC3209] MUST be used to refresh the SRLG
   information if the SRLG change is to be communicated to other nodes
   according to the local node's policy.  If local policy is that the
   SRLG change should be suppressed or would result in no change to the
   previously signaled SRLG-list, the node SHOULD NOT send an update.

5.3.  Compatibility

   A node that does not recognize the SRLG Collection Flag in the
   Attribute Flags TLV is expected to proceed as specified in RFC 5420
   [RFC5420].  It is expected to pass the TLV on unaltered if it appears
   in a LSP_ATTRIBUTES object, or reject the Path message with the
   appropriate Error Code and Value if it appears in a
   LSP_REQUIRED_ATTRIBUTES object.

   A node that does not recognize the SRLG RRO sub-object is expected to
   behave as specified in RFC 3209 [RFC3209]: unrecognized subobjects
   are to be ignored and passed on unchanged.

6.  Manageability Considerations

6.1.  Policy Configuration

   In a border node of inter-domain or inter-layer network, the
   following SRLG processing policy should be capable of being
   configured:

   o  Whether the SRLG IDs of the domain or specific layer network can
      be exposed to the nodes outside the domain or layer network, or
      whether they should be summarized, mapped to values that are
      comprehensible to nodes outside the domain or layer network, or
      removed entirely.

6.2.  Coherent SRLG IDs

   In a multi-layer multi-domain scenario, SRLG ids may be configured by
   different management entities in each layer/domain.  In such
   scenarios, maintaining a coherent set of SRLG IDs is a key
   requirement in order to be able to use the SRLG information properly.
   Thus, SRLG IDs must be unique.  Note that current procedure is
   targeted towards a scenario where the different layers and domains
   belong to the same operator, or to several coordinated administrative
   groups.  Ensuring the aforementioned coherence of SRLG IDs is beyond
   the scope of this document.

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   Further scenarios, where coherence in the SRLG IDs cannot be
   guaranteed are out of the scope of the present document and are left
   for further study.

7.  Security Considerations

   This document builds on the mechanisms defined in [RFC3473], which
   also discusses related security measures.  In addition, [RFC5920]
   provides an overview of security vulnerabilities and protection
   mechanisms for the GMPLS control plane.  The procedures defined in
   this document permit the transfer of SRLG data between layers or
   domains during the signaling of LSPs, subject to policy at the layer
   or domain boundary.  It is recommended that domain/layer boundary
   policies take the implications of releasing SRLG information into
   consideration and behave accordingly during LSP signaling.

8.  IANA Considerations

8.1.  RSVP Attribute Bit Flags

   IANA has created a registry and manages the space of attributes bit
   flags of Attribute Flags TLV, as described in section 11.3 of
   [RFC5420], in the "Attributes TLV Space" section of the "Resource
   Reservation Protocol-Traffic Engineering (RSVP-TE) Parameters"
   registry located in https://www.iana.org/assignments/rsvp-te-
   parameters/rsvp-te-parameters.xhtml.  It is requested that IANA makes
   assignments from the Attribute Bit Flags.

   This document introduces a new Attribute Bit Flag:

   o  Bit number: TBD (early allocation requested)

   o  Defining RFC: this I-D

   o  Name of bit: SRLG Collection Flag

   o  The meaning of the SRLG Collection Flag is defined in this I-D.

8.2.  ROUTE_RECORD Object

   IANA has made the following assignments in the "Class Names, Class
   Numbers, and Class Types" section of the "RSVP PARAMETERS" registry
   located at http://www.iana.org/assignments/rsvp-parameters.  We
   request that IANA make assignments from the ROUTE_RECORD RFC 3209
   [RFC3209] portions of this registry.

   This document introduces a new RRO sub-object:

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             Type          Name                       Reference
             ---------     ----------------------     ---------
             TBD (early    SRLG sub-object            This I-D
             allocation
             requested)

8.3.  Policy Control Failure Error subcodes

   IANA has made the following assignments in the "Error Codes and
   Globally-Defined Error Value Sub-Codes" section of the "RSVP
   PARAMETERS" registry located at http://www.iana.org/assignments/rsvp-
   parameters.  We request that IANA make assignments from the Policy
   Control Failure Sub-Codes registry.

   This document introduces a new Policy Control Failure Error sub-code:

   o  Error sub-code: TBD (early allocation requested)

   o  Defining RFC: this I-D

   o  Name of error sub-code: SRLG Recording Rejected

   o  The meaning of the SRLG Recording Rejected error sub-code is
      defined in this I-D

9.  Acknowledgements

   The authors would like to thank Igor Bryskin, Ramon Casellas, Lou
   Berger and Alan Davey for their useful comments and improvements to
   the document.

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.

   [RFC3473]  Berger, L., "Generalized Multi-Protocol Label Switching
              (GMPLS) Signaling Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.

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   [RFC5420]  Farrel, A., Papadimitriou, D., Vasseur, JP., and A.
              Ayyangarps, "Encoding of Attributes for MPLS LSP
              Establishment Using Resource Reservation Protocol Traffic
              Engineering (RSVP-TE)", RFC 5420, February 2009.

10.2.  Informative References

   [RFC4202]  Kompella, K. and Y. Rekhter, "Routing Extensions in
              Support of Generalized Multi-Protocol Label Switching
              (GMPLS)", RFC 4202, October 2005.

   [RFC4206]  Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP)
              Hierarchy with Generalized Multi-Protocol Label Switching
              (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.

   [RFC5920]  Fang, L., "Security Framework for MPLS and GMPLS
              Networks", RFC 5920, July 2010.

   [RFC6107]  Shiomoto, K. and A. Farrel, "Procedures for Dynamically
              Signaled Hierarchical Label Switched Paths", RFC 6107,
              February 2011.

Authors' Addresses

   Fatai Zhang (editor)
   Huawei
   F3-5-B RD Center
   Bantian, Longgang District, Shenzhen  518129
   P.R.China

   Email: zhangfatai@huawei.com

   Oscar Gonzalez de Dios (editor)
   Telefonica Global CTO
   Distrito Telefonica, edificio sur, Ronda de la Comunicacion 28045
   Madrid  28050
   Spain

   Phone: +34 913129647
   Email: oscar.gonzalezdedios@telefonica.com

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   Dan Li
   Huawei
   F3-5-B RD Center
   Bantian, Longgang District, Shenzhen  518129
   P.R.China

   Email: danli@huawei.com

   Cyril Margaria
   Suite 4001, 200 Somerset Corporate Blvd.
   Bridgewater, NJ  08807
   US

   Email: cyril.margaria@gmail.com

   Matt Hartley
   Cisco

   Email: mhartley@cisco.com

   Zafar Ali
   Cisco

   Email: zali@cisco.com

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