IETF- 56

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IETF- 56 TE WG- SAN FRANCISCO
Inter-AS MPLS Traffic Engineering
draft-vasseur-inter-AS-TE-00.txt 
Jean-Philippe Vasseur Cisco Systems
Raymond Zhang - Infonet
draft-vasseur-inter-AS-TE-00.txt
IETF-56 San Francisco
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• Inter-AS MPLS Traffic Engineering requirements
  draft draft-zhang-mpls-interas-te-req-02.txt (TE
  WG)
• Inter-AS MPLS Traffic Engineering (solution
  draft)
• draft-vasseur-inter-AS-te-00.txt (WG to be
  decided once inter-AS reqs draft adopted as a WG
  doc)

Scenario 1 per-AS TE LSP Path computation
Scenario 2 distributed path computation server
draft-vasseur-inter-AS-TE-00.txt
IETF-56 San Francisco
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Scenario 1 per-AS TE LSP Path Computation
ASBR2
ASBR1
ASBR5
ASBR6
B
ASBR4
ASBR3
A
AS2
ASBR8
ASBR7
AS2
AS1
TE LSP defined as a set of loose hops Pref1
A-ASBR1(L)-ASBR2(L)-ASBR7(L)-ASBR8(L)-B(L) Pref2
A-ASBR3(L)-ASBR4(L)-ASBR7(L)-ASBR8(L)-B(L)
Semi-dynamic path computation HE crankback in
case of Call admission failure Option for ASBR
discovery
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• Scenario 1 additional drafts .
• Inter-AS TE LSP reoptimization (MUST in the
  requirement draft)
• draft-vasseur-mpls-loose-path-reopt-01.txt
  proposes a set of mechanisms allowing
• A TE LSP Head-End LSR to trigger on every LSR
  (whose next hop is a loose hop) the re
  evaluation of the current path in order to detect
  a potential more optimal path (performed via
  signalling)
• An LSR whose next hop is a loose-hop to signal,
  upon request or not, to the TE LSP head-end
  whether or not a better (lower cost) path exists
• If and only if at least a better path exist in
  an area/AS, the HE LSR triggers a non disruptive
  TE Reroute (Make before break).
• ASBR Node protection (with MPLS TE Fast Reroute
  facility backup (MUST in the requirements
  draft)
• draft-vasseur-mpls-nodeid-subobject-00.txt
  proposes to specify an additional flag of the
  RRO IPv4/IPv6 sub-object used for the backup
  tunnel selection for inter-AS TE LSP protected
  by MPLS TE Fast Reroute (Facility backup) in
  case of ASBR node failure

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Scenario 2 distributed path computation server


ASBR2
ASBR1

ASBR5
ASBR6
B
ASBR4
ASBR3
A
ASBR8
ASBR7
AS3
AS2
AS1
ASBR1 build a virtual SPT (the shortest path is
built using a backward recursive computation)
Virtual SPT
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Summary

• Scenario 1 per-AS TE LSP Path computation
• - No impact on RSVP/IGP scalability,
• Semi-dynamic,
• Small set of protocol extensions required,
• No optimal end to end path
• Diverse path computation not always possible
  (Path protection, load balancing)
• Call set up failure,
• Support of end to end reoptimization
  (timer/event driven)
• Support of FRR Bypass for ASBR protection

• Scenario 2 distributed path computation server
• No impact on RSVP/IGP scalability,
• Dynamic,
• - Implementation more complex,
• Optimal end to end path
• Diverse path computation always possible (Path
  protection, load balancing)
• No call set up failure
• Support of end to end reoptimization
• Support of FRR Bypass for ASBR protection
• TE LSP local protection recommended

Both scenario 1 and 2 are compliant with the set
of requirements defined in draft-zhang-mpls-intera
s-te-req-02.txt
draft-vasseur-inter-AS-TE-00.txt
IETF-56 San Francisco
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Conclusion

• Next step start discussion