Encoding of Objective Functions in PCEP draft-ietf-pce-of-01.txt

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Encoding of Objective Functions
in PCEP
draft-ietf-pce-of-01.txt



J.L. Le Roux (France
Telecom) J.P.
Vasseur (Cisco Systems)
Y. Lee (Huawei)
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Background

• The computation of one or a series of TE-LSPs is
  subject to an objective function (OF)
• Unsynchronized computation Minimum cost path,
  shortest widest path, widest shortest path, etc.
• Synchronized computation Minimize the load on
  the most loaded link, minimize the global
  bandwidth consumption, etc.
• This drafts covers
• the discovery of objective function supported by
  a PCE
• the indication, in a request/response, of the
  objective function required/used

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Changes since last version

• Draft adopted as WG document in Chicago
• Moved OF discovery from PCED to PCEP
• Factorized the OF in the reply for a set of
  synchronized requests
• Rewordings for the sake of clarity

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Discovery of objective functions

• Used to rely on PCE Discovery (OSPF/ISIS) A new
  sub-TLV, OF-List, carried in the OSPF/ISIS PCED
  TLV
• Carried the list of supported objective functions
• For scalability consideration, the IESG requested
  to close the OSPF/ISIS PCED TLV gt no new sub-TLV
  can be added
• So OF Discovery can no longer rely on the PCED
  TLV
• Moved OF discovery from ISIS/OSPF to PCEP
• This follows requirements set forth in 4657 and
  4674 regarding the discovery of detailed
  capabilities
• A new PCEP TLV has been defined, the OF-List TLV,
  to be carried within the OPEN object
• This allows discovering the OF supported by a PCE
  during PCEP session setup phase

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OF Factorization in PCRep

• The OF object in a PCRep for a set of
  synchronized requests MUST directly follow the
  corresponding SVEC object and MUST NOT be
  repeated for each elementary request

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Next Steps

• Straightforward PCEP extension
• Stable specification
• Running code
• Need for WG feedback
• A new revision accounting for WG comments to be
  submitted before end December
• Then ready for WG last call

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ThanksQuestions?