MPLS Generic Associated Channel draft-bocci-mpls-tp-gach-gal-00.txt

1
MPLS Generic Associated Channeldraft-bocci-mpls-t
p-gach-gal-00.txt

• Matthew Bocci (ALU) Martin Vigoureux (ALU)
  (Eds.)
• George Swallow (Cisco), David Ward (Cisco), Rahul
  Aggarwal (Juniper)

2
Objective

• Objective is to generalise the PW associated
  channel to LSPs and MPLS sections
• Allow a common set of OAM and other FCAPs
  functions
• Allow future extensibility of such functions for
  MPLS in general, including MPLS-TP

3
Background

• Two drafts introduced in Dublin
• draft-bocci-pwe3-mpls-tp-ge-ach-00.txt
• Generalise PW ACH to LSPs and MPLS sections
  (GE-ACH)
• draft-vigoureux-mpls-tp-gal-00
• Created a new Generic Alert Label (GAL) to
  indicate the presence of ACH immediately after
  BoS on a LSP or section
• Differentiate specific packets (e.g. OAM) from
  others, such as normal user-plane ones,
• Proposed Label 13
• Comments in Dublin that the context of the GAL
  and GE-ACH needed to be better explained

4
Generic Associated Channel Header

• Identical to the existing PW ACH of RFC 4385

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
-------------------------
------- 0 0 0 1Version
Reserved Channel Type
------------------------
--------
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Generic Alert Label

• Example label stack for LSPs

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
-------------------------
------- LSP Label
TC S TTL
-------------------------
------- GAL
TC S TTL
-------------------------
-------
Generic-ACH
-------------------------
-------
. .
MPLS-TP OAM packet
. .

-------------------------
-------

• GAL is NOT used for PWs (existing control word
  mechanisms apply)
• GAL and G-ACH ONLY present on LSP OAM packets
• No need for control word on LSP user packets

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Generic Alert Label

• Example label stack for MPLS Sections

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
-------------------------
------- GAL
TC S TTL
-------------------------
-------
Generic-ACH
-------------------------
-------
. .
MPLS-TP OAM packet
. .

-------------------------
-------

• No need for LSP label

7
draft-bocci-mpls-tp-gach-gal-00Merger of two
original drafts

• Updated terminology (G-ACH GE-ACH)
• Clarified use of IP demux of MPLS OAM packets by
  default in MPLS in general, but G-ACH used where
  IP demux not available
• Addressed requests for flexible use of ACH
  channels for experimentation and testing by
  allocating range of experimental code points
• 0 - 32751 IETF Consensus
• 32752 - 32767 Experimental (as per RFC3692)

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draft-bocci-mpls-tp-gach-gal-00

• CompatibilityLSR or PE MUST discard G-ACH
  packets if
• Not G-ACH capable,
• Cannot process packets on indicated G-ACH channel
• Has not agreed to process packets on indicated
  channel
• and MAY increment a counter and issue
  system/SNMP notification
• This updates RFC5085 behaviour for MPLS PWs
• Added more detailed security considerations.

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Next Steps

• Consensus to move to working group draft
• Some comments already received
• GAL always BoS in MPLS-TP, but not necessarily so
  in other MPLS applications
• Other comments from the list?
• Update draft to draft-ietf-mpls-tp-gach-gal-00.txt