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Versions: (draft-zhang-ccamp-srlg-fa-configuration) 00 01 02 03 04 05 06 07 08 09 draft-ietf-teas-rsvp-te-srlg-collect

Network Working Group                                      F. Zhang, Ed.
Internet-Draft                                                     D. Li
Intended status: Standards Track                                  Huawei
Expires: April 04, 2014                         O. Gonzalez de Dios, Ed.
                                                          Telefonica I+D
                                                             C. Margaria
                                                  Nokia Siemens Networks
                                                              M. Hartley
                                                                   Cisco
                                                        October 01, 2013


           RSVP-TE Extensions for Collecting SRLG Information
                draft-ietf-ccamp-rsvp-te-srlg-collect-03

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.

   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 http://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 April 04, 2014.

Copyright Notice

   Copyright (c) 2013 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   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.  RSVP-TE Requirements  . . . . . . . . . . . . . . . . . . . .   3
     2.1.  SRLG Collection Indication  . . . . . . . . . . . . . . .   3
     2.2.  SRLG Collection . . . . . . . . . . . . . . . . . . . . .   3
     2.3.  SRLG Update . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  RSVP-TE Extensions (Encoding) . . . . . . . . . . . . . . . .   3
     3.1.  SRLG Collection Flag  . . . . . . . . . . . . . . . . . .   3
     3.2.  SRLG sub-object . . . . . . . . . . . . . . . . . . . . .   4
   4.  Signaling Procedures  . . . . . . . . . . . . . . . . . . . .   5
     4.1.  SRLG Collection . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  SRLG Update . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Manageability Considerations  . . . . . . . . . . . . . . . .   7
     5.1.  Policy Configuration  . . . . . . . . . . . . . . . . . .   7
     5.2.  Coherent SRLG IDs . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     7.1.  RSVP Attribute Bit Flags  . . . . . . . . . . . . . . . .   8
     7.2.  ROUTE_RECORD Object . . . . . . . . . . . . . . . . . . .   8
       7.2.1.  SRLG sub-object Flags . . . . . . . . . . . . . . . .   9
     7.3.  Policy Control Failure Error subcodes . . . . . . . . . .   9
   8.  Contributing Authors  . . . . . . . . . . . . . . . . . . . .   9
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   10. Normative 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
   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.






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   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.  RSVP-TE Requirements

2.1.  SRLG Collection Indication

   The head 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 head
   node.

2.2.  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.

2.3.  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.

3.  RSVP-TE Extensions (Encoding)

3.1.  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

   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 head and tail node along the setup of the
   LSP.

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




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3.2.  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     |    Flags      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 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 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.

   Flags

   The Flags are used to indicate properties of the SRLG-list contained
   in the sub-object.

      0x01 = SRLG-list edited

      If set, this flag indicates that the SRLG-list contained in the
      RRO sub-object has been edited in some way by a node during
      signaling in accordance with that node's policy.

      0x02 = Partial SRLG-list

      If set, this flag indicates that the SRLG-list contained in this
      RRO sub-object is known to be incomplete.

   SRLG Id




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   The 32-bit identifier of the SRLG.

   Reserved

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

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

4.  Signaling Procedures

4.1.  SRLG Collection

   Typically, the head node gets the route information of an LSP by
   adding a RRO which contains the sender's IP addresses in the Path
   message.  If a head node also desires SRLG recording, it sets the
   SRLG Collection Flag in the Attribute Flags TLV which can be carried
   either in an LSP_REQUIRED_ATTRIBUTES Object if the collection is
   mandatory, or in an LSP_ATTRIBUTES Object if 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 is set,
   if local policy determines that the SRLG information should not 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 is set, if local policy
   determines that the SRLG information should not 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 the SRLG sub-object(s) in the Path RRO.

   If local policy permits the recording of the SRLG information, the
   processing node SHOULD add an SRLG sub-object to the RRO to carry the
   local SRLG information.  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 forwarding
   of the Path message hop by hop.  When the Path message arrives at the
   tail node, the tail node can get the SRLG information from the RRO.





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   Before the Resv message is sent to the upstream node, the tail node
   adds the SRLG subobject with the SRLG value(s) associated with the
   local hop to the Resv RRO in a similar manner to that specified above
   for the addition of Path RRO sub-objects by midpoint nodes.

   When a node receives a Resv message for an LSP for which SRLG
   Collection is specified, if local policy determines that the SRLG
   information should not 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.  Otherwise, if local policy allows to provide the SRLG
   informatin, it MUST add an SRLG sub-object to the RRO to carry the
   SRLG information in the upstream direction.  When the Resv message
   arrives at the head node, the head node can get the SRLG information
   from the RRO in the same way as the tail 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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   It is noted that a node (e.g. the edge node of a domain) may edit the
   RRO to remove the route information (e.g. node, interface identifier
   information) before forwarding it due to some reasons
   (e.g.confidentiality or reduce the size of RRO).  A node MAY edit
   SRLG information within the RRO of a Path or Resv message if dictated
   by its local policy.  If a node makes such an alteration to an
   existing RRO object, it SHOULD set the "SRLG-list edited" flag in the
   edited RRO sub-object to indicate to other nodes that this has been
   done.

4.2.  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 need not send an update

5.  Manageability Considerations

5.1.  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 or removed entirely.

   o  If SRLGs are summarized or removed, whether the "SRLG-list edited"
      flag is set in affected SRLG RRO-sub-objects and .

   o  If SRLGs are summarized or removed, whether the "SRLG-list edited"
      and "Partial SRLG-list" flags are set in affected SRLG RRO-sub-
      objects.

5.2.  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



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   groups.  Ensuring the aforementioned coherence of SRLG IDs is beyond
   the scope of this documen

   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.

6.  Security Considerations

   This document does not introduce any additional security issues above
   those identified in [RFC5920][RFC3209][RFC3473]

7.  IANA Considerations

7.1.  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 (10)

   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

7.2.  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:

          Type       Name                       Reference
          ---------  ----------------------     ---------
          TBD (34)   SRLG sub-object            This I-D




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7.2.1.  SRLG sub-object Flags

   It is requested that the IANA ceates a registry to manage the space
   of bit flags of the SRLG sub-object defined in this document.  It is
   requested that IANA makes assignments from the SRLG sub-object Flags.

   This document introduces two new SRLG sub-object Flags.

            +------------+-------------------+---------------+
            | Bit Number |        Name       |   Reference   |
            +------------+-------------------+---------------+
            |     1      |  SRLG-list edited | This document |
            |     2      | Partial SRLG-list | This document |
            +------------+-------------------+---------------+


7.3.  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 (108)

   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

8.  Contributing Authors

      Zafar Ali
      Cisco Systems
      zali@cisco.com

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.





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10.  Normative References

   [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.

   [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.

   [RFC5150]  Ayyangar, A., Kompella, K., Vasseur, JP., and A. Farrel,
              "Label Switched Path Stitching with Generalized
              Multiprotocol Label Switching Traffic Engineering (GMPLS
              TE)", RFC 5150, February 2008.

   [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


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

   Email: danli@huawei.com



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   Oscar Gonzalez de Dios (editor)
   Telefonica I+D
   Don Ramon de la Cruz
   Madrid  28006
   Spain

   Phone: +34 913328832
   Email: ogondio@tid.es


   Cyril Margaria
   Nokia Siemens Networks
   St Martin Strasse 76
   Munich  81541
   Germany

   Phone: +49 89 5159 16934
   Email: cyril.margaria@nsn.com


   Matt Hartley
   Cisco

   Email: mhartley@cisco.com



























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