P2MP MPLSTE Fast Reroute with P2MP Bypass Tunnels draftietfmplsp2mptebypass01'txt

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P2MP MPLS-TE Fast Reroute
with P2MP Bypass Tunnels
draft-ietf-mpls-p2mp-te-bypa
ss-01.txt


J.L.
Le Roux (France Telecom)
R. Aggarwal (Juniper)
J.P. Vasseur (Cisco
Systems)
M. Vigoureux (Alcatel-Lucent)

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Document Overview

• Limitations of P2P bypass tunnels to protect a
  P2MP LSP gt Traffic duplication
• To overcome these limitations this draft defines
  extensions to the FRR procedures to support P2MP
  Bypass tunnels
• Retain scalability advantages of MPLS label
  stacking
• Avoids sending multiple copies of a packet on
  some links during failure
• During failure the traffic is tunneled within one
  or more P2MP bypass towards the set of Merge
  Points thanks to label stacking
• Inner label backup LSP Label, used on the MP to
  forward traffic to the protected LSP
• Outer label P2MP Bypass tunnel Label
• To avoid data replication on the PLR, a same
  inner label is assigned by the PLR to all MPs on
  a given P2MP bypass
• following RSVP-TE Upstream Label Assignment
  procedure
• draft-ietf-mpls-rsvp-upstream

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Changes since last version

• Draft adopted as WG document in May
• No PHP on the bypass tunnel to allow for context
  identification
• Bypass signaled with the No-PHP desired bit, as
  specified in
  draft-ali-mpls-rsvp-te-no-php-oob-mapping
• Reversion Entirely rely on procedures defined in
  RFC4090
• global and local revertive modes
• Clarifications on PLR location local or remote
• Combination of P2P and P2MP Bypass tunnels for
  backward comp
• Bypass tunnel selection options clarified
• Link protection procedures clarified
• Procedures for Partial protection
• Some rewordings for the sake of clarity

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Combination of P2P and P2MP Bypass
No Up Label capable
P2P Bypass

• P2MP bypass and P2P bypass can be used in
  conjunction
• For MP on P2P bypass gt follow procedures in 4875
• For MP on P2MP Bypass gt follow procedures in
  this doc
• No upstream label assignment for MP leaves of P2P
  bypass
• Allows for backward compatibility with MP that do
  not support upstream label assignment

P2MP Bypass
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P2MP Bypass Tunnel selection options

• Various options to protect a P2MP LSP with P2MP
  bypass
• 1 A single P2MP Bypass tunnel whose leaves
  exactly match the set of MPs
• 2 A single P2MP Bypass tunnel whose leaves are a
  superset of the set of MPs
• Leaves that are not MP drop the traffic
• 3 Several P2MP bypass tunnels whose combined
  leaves cover all MPs
• These options differ in terms of bandwidth
  consumption and number of P2MP bypass to be
  maintained
• P2MP Hierarchy gt Tension between control plane
  and data plane optimization
• The choice depends on the desired state/bandwidth
  tradeoff, and the operational complexity

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Link protection with P2P Bypass

• Default procedure (defined in RFC4875)
• May lead to traffic duplication on some links
  during failure
• When the bypass follows another downstream link
  on the P2MP LSP

Protected P2MP TE-LSP
P2P Bypass tunnel
Duplication
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Link Protection with P2MP Bypass
No Duplication
Protected P2MP TE-LSP
P2MP Bypass tunnel

• OPTIONAL procedure A link MAY be protected by A
  P2MP bypass
  that tunnels traffic towards MPs downstream to
  the PLR
• Some MPs are downstream to the PLR but not
  downstream to the failed element (not impacted by
  the failure)
• The PLR must stop sending traffic to these MP
  within the protected P2MP LSP
• Allows avoiding sending twice the traffic on a
  downstream link

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P2MP Partial Protection
Uncovered MP
P2MP Primary Partial prot allowed

• In some cases the PLR may not be able to find a
  set of P2P and/or P2MP Bypass Tunnels that cover
  all merge points
• "P2MP Partial Protection" Only a subset of MP
  are covered
• upon failure, traffic will not be delivered to
  all leaf LSRs
• Default PLR behavior Full protection if feasible
  else no protection
• The Ingress LSR may request for "P2MP Partial
  Protection", such that if a P2MP LSP cannot be
  fully protected it is partially protected

P2MP Bypass
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Next Steps

• Need to align with the mpls-upstream draft gt The
  PLR assigns upstream labels from a single label
  space
• WG feedback required
• A new revision to be submitted before Vancouver
  meeting
• figures, examples, clarifications

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ThanksQuestions?
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Appendix
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Limitations of the P2P Bypass approachnode
protection

• Using P2P bypass tunnels for P2MP LSP node
  protection leads to traffic duplication on some
  links during failure

Protected P2MP TE-LSP
P2P Bypass tunnel
Duplication
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Link protection with P2P Bypass

• Default procedure (defined in RFC4875)
• May lead to traffic duplication on some links
  during failure
• When the bypass follows another downstream link
  on the P2MP LSP

Protected P2MP TE-LSP
P2P Bypass tunnel
Duplication
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Protection with P2MP Bypass
Protected P2MP TE-LSP
P2MP Bypass tunnel
P2MP tunnel B
P2MP tunnel P
P2MP tunnel B ILM (label 21) 50 -gt 28, R6

P2MP tunnel B ILM (label 23) 50 -gt 37, R7

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P2MP Bypass Tunnel SelectionOption 1
Protected P2MP TE-LSP
P2MP Bypass tunnel
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P2MP Bypass Tunnel SelectionOption 2
Protected P2MP TE-LSP
P2MP Bypass tunnel
drop
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P2MP Bypass Tunnel SelectionOption 3
Protected P2MP TE-LSP
P2MP Bypass tunnel