LSP Stitching with Generalized MPLS TE draft-ietf-ccamp-lsp-stitching-01.txt

1
LSP Stitching with Generalized MPLS
TEdraft-ietf-ccamp-lsp-stitching-01.txt

• Arthi Ayyangar (arthi_at_juniper.net)
• Jean Philippe Vasseur (jpv_at_cisco.com)

2
Changes from 00 version

• Editorial cleanup and rewrite
• Incorporated comments from WG
• relevance of signaling adjacency between LSP
  segment end points
• label allocation procedure over LSP segment for
  bidirectional LSPs
• teardown procedures for e2e LSP over LSP segment
• relationship between regions based on switching
  capabilities and LSP stitching
• triggers for dynamic setup of LSP segment for LSP
  stitching

3
Discussion on list

• Are the control plane procedures for LSP
  stitching REQUIRED for PSC and non-PSC LSPs ?
• Yes
• Should we allow LSP stitching procedures (control
  data planes) while traversing region boundaries
  ?
• PSC-n to PSC-(n1) NO
• Non-PSC NO/YES ?
• Different opinions on this
• Why not simply use LSP hierarchy in this case ?
• Is there any specific benefit of using LSP
  stitching instead of LSP hierarchy for this case
  (control data plane) ?
• Would such nodes even use LSP stitching control
  plane procedures as described in this ID or
  would they simply use LSP hierarchy procedures
  in control plane but stitch in data plane?
• Does it affect anyone if LSP stitching between
  different SCs were disallowed ?

4
Issue of Bidirectional LSPs

• Jean Louis brought up this point
• GMPLS nodes use Upstream Label to detect
  bi-directionality of the LSP
• When no Upstream Label is exchanged over the LSP
  segment hop, the information conveying
  bi-directionality is lost
• Solution options
• Some flag set by head end of e2e LSP to be used
  as an alternative to Upstream Label, when
  Upstream Label is missing
• Two different signaling parameters to mean the
  same thing
• Not compatible with existing procedures
• Some flag/object set by the stitching node, only
  along the LSP segment hop
• Continue to send Upstream Label in Path and Label
  in Resv over the LSP segment hop, but choose a
  unique label value to denote stitching
• How does this affect Generalized Labels that have
  no restriction on value to be used ? E.g. Port
  Numbers
• Should we even allow bidirectional LSP to
  traverse two different unidirectional LSP
  segments ?
• OR
• Any label value (no need for unique value) and
  simply place the onus on the receiver to ignore
  any Label/Upstream Label in case of stitching
• This is already stated in the ID. Stricter rules.

5
Next steps

• LSP stitching signaling procedures are currently
  optional for non-PSC
• Make this a requirement, similar to PSC?
• Resolve rules for stitching between different SCs
• Fix the issue of absence of Upstream Label for
  bidirectional LSPs based on options listed before
• There has been more discussion/comments on list
  after version 01
• Adopt additional comments and publish early
  revision