LSP Attribute in ERO
draft-margaria-ccamp-lsp-attribute-ero-01

CCAMP                                                   C. Margaria, Ed.
Internet-Draft                                    Nokia Siemens Networks
Intended status: Standards Track                           D. Schroetter
Expires: January 16, 2013                                   NUTS:iX GmbH
                                                           G. Martinelli
                                                                   Cisco
                                                                S. Balls
                                                               B. Wright
                                                              Metaswitch
                                                           July 15, 2012

                          LSP Attribute in ERO
               draft-margaria-ccamp-lsp-attribute-ero-01

Abstract

   LSP attributes can be specified or recorded for whole path, but they
   cannot be targeted to a specific hop.  This document proposes
   alternative ways to extend the semantic for RSVP ERO object to target
   LSP attributes to a specific hop.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   publication of this document.  Please review these documents

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   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Contributing Authors . . . . . . . . . . . . . . . . . . .  3
     1.2.  Requirements Language  . . . . . . . . . . . . . . . . . .  3
   2.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Solutions  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  ERO LSP Attribute Subobject  . . . . . . . . . . . . . . .  5
       3.1.1.  ERO LSP_ATTRIBUTE subobject  . . . . . . . . . . . . .  5
       3.1.2.  Procedures . . . . . . . . . . . . . . . . . . . . . .  6
       3.1.3.  Pros and Cons  . . . . . . . . . . . . . . . . . . . .  6
     3.2.  Information carried in the LSP Attribute object  . . . . .  7
       3.2.1.  Solution overview  . . . . . . . . . . . . . . . . . .  7
       3.2.2.  ERO Hop Info Index Subobject . . . . . . . . . . . . .  7
       3.2.3.  RRO Hop Info Index Subobject . . . . . . . . . . . . .  8
       3.2.4.  LSP Attribute Hop Info TLV . . . . . . . . . . . . . .  8
       3.2.5.  Procedures . . . . . . . . . . . . . . . . . . . . . .  9
       3.2.6.  Pros and Cons  . . . . . . . . . . . . . . . . . . . . 10
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   6.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 13
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 14
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15

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1.  Introduction

   Generalized MPLS (GMPLS) Traffic Engineering (TE) Label Switched
   Paths (LSPs) can be route-constrained by making use of the Explicit
   Route (ERO) object and related sub-objects as defined in [RFC3209],
   [RFC3473], [RFC3477], [RFC4873], [RFC4874], [RFC5520] and [RFC5553].
   This document proposes mechanisms to target LSP attributes at a
   specific hop.  This document present several solutions for
   discussion, final document will contains only one document after WG
   consensus.

1.1.  Contributing Authors

1.2.  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].

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2.  Requirements

   The requirement is to provide a generic mechanism to carry
   information related to specific nodes when signaling an LSP.  This
   document does not restrict what that information can be used for.
   LSP attribute defined [RFC5420] should be expressed in ERO and SERO
   objects.

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3.  Solutions

3.1.  ERO LSP Attribute Subobject

   The ERO LSP Attributes subobject may be carried in the ERO or SERO
   object if they are present.  The subobject uses the standard format
   of an ERO subobject.

3.1.1.  ERO LSP_ATTRIBUTE subobject

   The length is variable and content MUST be the same as for the
   LSP_ATTRIBUTE object with Attributes TLVs.

   The ERO LSP attribute subobject is defined as follows:

      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|    Type     |     Length    |    Reserved                 |R|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      //                      Attributes TLVs                        //
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [RFC3209] for a description of L parameters.  The attributes TLV
   are encoded as defined in [RFC5420] section 3.

   Type  x TBD by IANA.

   Length  The Length contains the total length of the subobject in
      bytes, including the Type and Length fields.  The Length MUST be
      always divisible by 4.

   Reserved  Reserved, must be set to 0 when the subobject is inserted
      in the ERO, MUST NOT be changed when a node process the ERO and
      must be ignored on the node addressed by the preceding ERO
      subobjects

   R  This bit reflects the LSP_REQUIRED_ATTRIBUTE and LSP_ATTRIBUTE
      semantic.  When set indicates required LSP attributes to be
      processed by the node, when cleared the LSP attributes are not
      required as described in Section 3.1.2.

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   Attributes TLVs  as defined in [RFC5420] section 3.

3.1.2.  Procedures

   As described in [RFC3209] and [RFC3473] the ERO is managed as a list
   where each hop information starts with a subobject identifying an
   abstract node or link.  The LSP attribute subobject must be appended
   after the existing subobjects defined in [RFC3209], [RFC3473],
   [RFC3477], [RFC4873], [RFC4874], [RFC5520] and [RFC5553].  Several
   LSP attribute subobject MAY be present.

   If a node is processing an LSP attribute subobject and does not
   support handling of the subobject it will behave as described in
   [RFC3209] when an unrecognized ERO subobject is encountered.  This
   node will return a PathErr with error code "Routing Error" and error
   value "Bad EXPLICIT_ROUTE object" with the EXPLICIT_ROUTE object
   included, truncated (on the left) to the offending unrecognized
   subobject.

   When the R bit is set a node MUST examine the attribute TLV present
   in the subobject following the rules described in [RFC5420] section
   5.2.  When the R bit is not set a node MUST examine the attribute TLV
   present in the subobject following the rules described in [RFC5420]
   section 4.2.  If more than one ERO LSP attribute subobject having the
   R bit set is present, the first one MUST be processed and the others
   SHOULD be ignored.  If more than one ERO LSP attribute subject having
   the R bit cleared is present, the first one MUST be processed and the
   others SHOULD be ignored. [[anchor8: This need to be revised due to
   object length Pb --Ed.]]

3.1.3.  Pros and Cons

   This solution minimize the changes to the ERO object and so
   implementations can access all per-hop information when processing
   the ERO.

   However, per hop ERO sub-objects are limited to 255 bytes in length
   which may limit its extensibility.  Subsequent uses of this mechanism
   may wish to carry large amounts of contiguous information targeted at
   a single hop, which would need to split across multiple sub-objects.

   It also requires the sub-object to be duplicated multiple times in
   the ERO if the same information needs to be targeted at multiple
   nodes.

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3.2.  Information carried in the LSP Attribute object

3.2.1.  Solution overview

   A new ERO/RRO sub-object (Hop info index) is defined to be an index/
   pointer to a new TLV (Hop info) carried in the LSP_ATTRIBUTES object.
   This TLV is formed of sub-TLVs carrying information targeted at a
   specific node.

3.2.2.  ERO Hop Info Index Subobject

   The ERO Hop Info Index subobject may be carried in the ERO or SERO
   object if they are present.  The subobject uses the standard format
   of an ERO subobject.

   The ERO Hop info index subobject is defined as follows:

       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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |L|    Type     |     Length    |R| Res |        Index          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [RFC3209] for a description of L parameters.

   Type  Type x TBD by IANA.

   Length  The Length contains the total length of the subobject in
      bytes, including the Type and Length fields.  The Length MUST be
      always divisible by 4.

   Res  Reserved, must be set to 0 when the subobject is inserted in the
      ERO, MUST NOT be changed when a node process the ERO and must be
      ignored on the node addressed by the preceding ERO subobjects.

   R  If set, the corresponding Hop Info TLV should be handled as
      required and according to the rules of the LSP_REQUIRED_ATTRIBUTE
      object.  If clear, the corresponding Hop Info TLV should be
      handled as optional and according to the rules of the
      LSP_ATTRIBUTE object.  This bit is present in the ERO to allow
      attributes mandatory on some node and optional on others.

   Index  A value used to refer to an LSP Attribute Hop Info TLV
      containing information targeted at the node processing this ERO.

   Each hop on an LSP may have at most two ERO Hop Info Index subobjects
   associated with it.  One for optional attributes, and one for

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   required attributes.  Note that both these attributes are carried as
   separate Hop Info TLVs within the LSP_ATTRIBUTE object as they are
   not Required on the LSP as a whole.

3.2.3.  RRO Hop Info Index Subobject

   The RRO Hop Info Index subobject may be carried in the RRO object if
   it is present.  The subobject uses the standard format of an RRO
   subobject.

   The RRO Hop info index subobject is defined as follows:

     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    |  Res  |        Index          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type  x TBD by IANA.

   Length  The Length contains the total length of the subobject in
      bytes, including the Type and Length fields.  The Length MUST be
      always divisible by 4.

   Res  Reserved, must be set to 0 when the subobject is inserted in the
      ERO, MUST NOT be changed when a node process the ERO and must be
      ignored on the node addressed by the preceding ERO subobjects.

   Index  A value used to refer to an LSP Attribute Hop Info TLV
      containing information targeted at the node processing this ERO.

   Each hop on an LSP may have at most one RRO Hop Info Index subobjects
   associated with it.

3.2.4.  LSP Attribute Hop Info TLV

   The LSP Attribute Hop Info TLV may be carried in the LSP Attribute
   object if present.  It MUST be carried if an ERO Hop Info Index
   subobject is present in an ERO or SERO.

   The LSP Attribute Hop Info TLV is defined as follows:

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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              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Index         |    Reserved                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    //                      Sub-TLVs                               //
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type  x TBD by IANA.

   Length  The Length contains the total length of the subobject in
      bytes, including the Type and Length fields.  The Length MUST be
      always divisible by 4.

   Index  A value referred to by the Index field in the ERO Hop Info
      Index Subobject.

   Reserved  Reserved, must be set to 0 when the subobject is inserted
      in the LSP Attributes, MUST NOT be changed when a node process the
      LSP Attributes and must be ignored on the node processing the Hop
      Info TLV.

   Sub-TLVs  The information that is targeted at the specific hop or
      hops identified by the Index field.

   This document defines 1 sub-TLV type as below.

3.2.4.1.  Per Hop Attribute sub-TLV

   The Per Hop Attribute sub-TLV is defined to be identical to the
   Attributes TLV in [RFC5420].  Thus using this sub-TLV means any
   Attribute TLV can now be targeted at specific nodes using the LSP
   Attribute Hop Info TLV.

   Note that this means the number space for the Type value of
   Attributes for the whole LSP and those that can only ever be targeted
   at specific hops is shared.

3.2.5.  Procedures

   As described in [RFC3209] and [RFC3473] the ERO is managed as a list
   where each hop information starts with a subobject identifying an
   abstract node or link.  The Hop Info Index subobject must be appended

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   after the existing subobjects defined in [RFC3209], [RFC3473],
   [RFC3477], [RFC4873], [RFC4874], [RFC5520] and [RFC5553].  Only one
   Hop Info Index subobject may be added per node or link entry.

   If a node is processing an ERO Hop Info Index subobject and does not
   support handling of the subobject it will behave as described in
   [RFC3209] when an unrecognized ERO subobject is encountered.  This
   node will return a PathErr with error code "Routing Error" and error
   value "Bad EXPLICIT_ROUTE object" with the EXPLICIT_ROUTE object
   included, truncated (on the left) to the offending unrecognized
   subobject.

   If the node does supports the Hop Info Index subobject it will look
   for a corresponding (Both having the same Index field value) LSP
   Attribute Hop Info TLV in the LSP Attribute object.  If one is not
   present it will return a PathErr with error code "Routing Error" and
   error value "Bad EXPLICIT_ROUTE object".

   A node processing the LSP Attribute Hop Info TLV should not alter it.
   It is valid for multiple ERO entries to refer to the same Hop Info
   TLV, thus targeting the same information at multiple nodes.

   The RRO Hop Info Index subobject should be processed according to the
   rules of section 7.3.1 of [RFC5420].  A node inserting an RRO Hop
   Info Index subobject should not also insert an RRO Attributes
   subobject.

3.2.6.  Pros and Cons

   This solution is more complex in term of processing, but addresses
   some of the restrictions in the first solution.  LSP Attribute TLVs
   allow a length of up to 65535 bytes and the indexing system allows
   multiple nodes to target the same information.  The LSP Attribute Hop
   Info TLV may be extended by further sub-TLV types

   Other objects may be candidate to contain the Indexed ERO attribute,
   for instance the ERO object with a new C-Type.

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4.  IANA Considerations

   TBD once a final approach has been chosen.

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5.  Security Considerations

   None.

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6.  Acknowledgments

   The authors would like to thanks Lou Berger for his directions and
   Attila Takacs for inspiring this
   [I-D.kern-ccamp-rsvpte-hop-attributes].

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7.  References

7.1.  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.

   [RFC3477]  Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
              in Resource ReSerVation Protocol - Traffic Engineering
              (RSVP-TE)", RFC 3477, January 2003.

   [RFC4873]  Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
              "GMPLS Segment Recovery", RFC 4873, May 2007.

   [RFC4874]  Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes -
              Extension to Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE)", RFC 4874, April 2007.

   [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.

   [RFC5520]  Bradford, R., Vasseur, JP., and A. Farrel, "Preserving
              Topology Confidentiality in Inter-Domain Path Computation
              Using a Path-Key-Based Mechanism", RFC 5520, April 2009.

   [RFC5553]  Farrel, A., Bradford, R., and JP. Vasseur, "Resource
              Reservation Protocol (RSVP) Extensions for Path Key
              Support", RFC 5553, May 2009.

7.2.  Informative References

   [I-D.kern-ccamp-rsvpte-hop-attributes]
              Kern, A. and A. Takacs, "Encoding of Attributes of LSP
              intermediate hops using RSVP-TE",
              draft-kern-ccamp-rsvpte-hop-attributes-00 (work in
              progress), October 2009.

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Authors' Addresses

   Cyril Margaria (editor)
   Nokia Siemens Networks
   St Martin Strasse 76
   Munich,   81541
   Germany

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

   Dirk Schroetter
   NUTS:iX GmbH
   Langer Weg 88
   Eschborn,   65185
   DE

   Phone: +49 6173 39198411
   Email: dirk.schroetter@nutsix.de

   Giovanni Martinelli
   Cisco
   via Philips 12
   Monza  20900
   IT

   Phone: +39 039 209 2044
   Email: giomarti@cisco.com

   Steve Balls
   Metaswitch
   100 Church Street
   Enfield  EN2 6BQ
   UJ

   Phone: +44 208 366 1177
   Email: steve.balls@metaswitch.com

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   Ben Wright
   Metaswitch
   100 Church Street
   Enfield  EN2 6BQ
   UJ

   Phone: +44 208 366 1177
   Email: Ben.Wright@metaswitch.com

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