An%20Architecture%20for%20Multi-Segment%20Pseudo%20Wire%20Emulation%20Edge-to-Edge%20draft-bocci-bryant-pwe3-ms-pw-architecture-00.txt

1
An Architecture for Multi-Segment Pseudo Wire
Emulation Edge-to-Edgedraft-bocci-bryant-pwe3-ms-
pw-architecture-00.txt

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

2
Objectives Key Issues

• Objectives
• Document the main network scenarios for MS-PW
  applicability
• Define architectural framework
• Specify which protocol functions that we need
• Key Issues
• Applicability of MS-PWE3 vs. L2VPN
• Protocol Layering Model
• Network reference Models
• PE Reference Model
• Protocol Stack Reference Model
• Gaps

3
Applicability Domain of MS PWE3

• A MS-PW is a single PW that for technical or
  administrative reasons is segmented into a number
  of concatenated hops.
• From perspective of U-PE, MS-PW is
  indistinguishable from SS-PW.
• MS-PW abstracts complex PWs from the construction
  of a L2VPN
• PWE3 does not do PSN tunnel setup, PSN tunnel
  maintenance and routing, U-PE discovery
• PWE3 does do S-PE selection to reach a U-PE

4
Protocol Layering Model

• Same as RFC 3985 except
• Pseudo-wires may be considered to be a separate
  layer to the PSN tunnel.
• Independent of the PSN tunnel routing,
  operations, signalling and maintenance.
• Design of PW domains should not imply the
  underlying PSN routing domains are the same.
• MS-PW will reuse protocols of the PSN

5
Network Reference Models

• Intra-provider inter-provider

• Native lt-----------Pseudo
  Wire-----------gt Native
• Service
  Service
• (AC) lt-PSN1--gt lt-PSN2--gt
  (AC)
• V V V V V
  V
• ---- -----
  ----
• ---- UPE1SPE1
  UPE2 ----
• -------....PW.Seg't1........PW
  Seg't3.....----------
• CE1
  CE2
• -------....PW.Seg't2.......PW
  Seg't4.....----------
• ----
  ----
• ---- -----
  ----
• Provider Edge 1
  Provider Edge 2
• 
  
• 
  
• PW switching point
  
• 
  
• lt------------------- Emulated Service
  ------------------gt

6
PE Reference Model

• Pre-processing in U-PEs as RFC 3985
• Processing in S-PEs
• No native service processing
• Egress PW label mapping based on ingress label
• Static or dynamic config
• 11 mapping between ingress and egress PW

----------------------------------
-------- S-PE
Device
------------------------------------------
Ingress
Egress PW instance Single
Single PW Instance
ltgtX PW Instance Forwarder PW
Instance Xltgt

------------------------------------------
7
Protocol Stack Reference Model
Remove PSN1 demuxAdd PSN2 demuxApply policies

• ----------------
  ----------------
• Emulated Service
  Emulated Service
• (e.g., TDM, ATM)lt Emulated Service
  gt(e.g., TDM, ATM)
• ----------------
  ----------------
• Payload
  Payload
• Encapsulation lt Multi-segment Pseudo Wire
  gt Encapsulation
• ---------------- --------
  ----------------
• PW DemultiplexerltPW SegmentgtPW DemuxltPW
  SegmentgtPW Demultiplexer
• ---------------- --------
  ----------------
• PSN Tunnel, ltPSN Tunnelgt PSN ltPSN
  Tunnelgt PSN Tunnel,
• PSN Physical Physical
  PSN Physical
• Layers Layers
  Layers
• --------------- --------
  ----------------
• .......... ..........
  
• / \ / \
  
• / PSN \/ PSN
  \
• \ domain 1 / \ domain 2
  /
• \__________/ \__________/
  

8
Other Issues

• Control Plane
• Can be static or dynamic
• Gaps in current version of the draft
• Maintenance reference model
• Security issues

9
Conclusions

• Architecture is fundamental to the solution
• Would like to achieve consensus as early as
  possible
• Please provide comments and text to improve the
  draft!