An Architecture for Multi-Segment Pseudo Wire Emulation Edge-to-Edge draft-bocci-bryant-pwe3-ms-pw-architecture-01.txt

1
An Architecture for Multi-Segment Pseudo Wire
Emulation Edge-to-Edgedraft-bocci-bryant-pwe3-ms-
pw-architecture-01.txt

• Matthew Bocci (Alcatel)
• Stewart Bryant (Cisco)

2
Issues Addressed in new Version

• Terminology
• U-PE is now a T-PE (Terminating PE)
• Added Maintenance Reference Model
• More detail on S-PE functions
• Multiplexing layer at the S-PE
• Additional PW control considerations
• Security section

3
Maintenance Reference Model
For MS-PWs, signalling/maintenance now has an end
to end and a hop by hop context
lt------------- CE (end-to-end)
Signaling ------------gt

lt-------- MS-PW/T-PE Maintenance
-----gt lt---PW
Seg't--gt lt--PW Seg't---gt
Maintenance Maintenance


PSN PSN
lt-Tunnel1-gt lt-Tunnel2-gt
V V V Signaling V V V V
Signaling V V V V ----
----- ---- V
---- TPE1SPE1
TPE2 ----
-------......PW.Seg't1.........PW
Seg't3......------ CE1
CE2
-------......PW.Seg't2.........PW
Seg't4......------ ----
----
---- -----
---- Terminating
Terminating
Provider Edge 1 Provider
Edge 2

PW switching point

lt-------------------
-- Emulated Service -------------------gt
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S-PE Capabilities

• PW Demux Layer at the S-PE
• Demultiplex PWs from ingress PSN tunnels and to
  multiplex them into egress PSN tunnels.
• Each PW may contain multiple native service
  circuits, but S-PEs do not have visibility of
  this
• Do not change this level of multiplexing because
  they contain no NSP
• MS-PW Status
• Service is only up if all segments of both
  directions are up
• S-PE must be able to propagate status
  notifications between concatenated segments of a
  MS-PW
• Misconnection
• S-PEs can use PW type to ensure concatenated
  segments are compatible

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Other Issues

• Security
• Similar to RFC3985, with the addition of
• Security of S-PEs, particularly if dynamically
  selected or transiting multiple providers
• Behave similarly to ASBRs if connecting between
  providers
• S-PE needs to be able to determine authenticity
  of signalling request
• Mechanisms to prevent misconnection of a PW
  segment into a local AC at an S-PE if S-PE also
  incorporates T-PE functions

6
Conclusions

• Architecture is fundamental to the solution
• Would like to move forward to a working group
  draft
• Please provide comments and text to improve the
  draft!