1. Pseudo-Wire Protection
Ping Pan
IETF 65

2. Why? Tunnel-1 (BW1) Node 2 Node1 Tunnel-2 (BW2), backup Tunnel-1
PW (Important traffic)
Tunnel-1 (BW1)
Node 2
Node1
PW (Best effort)
Tunnel-2 (BW2), backup Tunnel-1
Switch-over
Conventional mechanism (e.g. MPLS FRR) would work, if
Tunnel-1 and Tunnel-2 have the same bandwidth (i.e.,BW1 = BW2)
All PW’s are equally important
Otherwise, if BW2 < BW1,
Important traffic may get dropped/delayed during network failure
PW protection:
Each PW needs to have its own “importance” and QoS level
During switch-over, preempt others if necessary

3. Design Considerations (1)
Need to work in single and multi-segment environment
Work with Generic ID FEC only
Working and protection PW’s must be uniquely identified
But make the use of AII/AGI may not be a good idea
working
protection
Need to know what to process

4. Design Considerations (2)
On Backup Path Determination
Carrying “ERO” should be optional
Use hop-by-hop forwarding for the working PW
Get “RRO” information from “PW Switching Point TLV (SP-TLV)”
Build the protection PW base on SP-TLV
May use SP-TLV for loop-detection
On CAC at each hop
Should be optional depending on traffic type
Other relevant protection information:
1:1 or 1:N: need to validate the need of 1:N
Fate-sharing: useful in multi-hop applications
Hot-standby vs. cold-standby

5. Protocol Extension Protection-TLV PW Status: Everything else:
Setup and Holding Preference Levels
Protection Type: hot or cold standby
Schemes: 1:1 or 1:N
Flags:
Fate-sharing allowed
Per-hop BW CAC required
Reference ID: unique identify working and protecting PW’s
PW Status:
Bad message, no bandwidth etc.
Everything else:
Keep as it is
AII/AGI must be the same on all working and protecting PW’s

6. How does it work? Protecting PW Working PW Node1 Node 2 Node 3
Run MHOP PW for working and protection PW setup
Use SP-TLV for loop detection
Use Protection-TLV and SP-TLV to forward working and protection PW’s
Forward failure status if not working
Run the Generic FEC procedure to setup the working PW
Run the Generic FEC procedure to setup the protection PW
When working, pointing user traffic to the protecting PW
During failure (learned from BFD etc.), switch over
Preempt traffic when needed…
Send out Label Mapping and setup the working PW
When working, setup the protecting PW (base on SP-TLV…)
When working, pointing user traffic to the protecting PW
During failure (learned from BFD etc.), switch over
Preempt traffic when needed…

7. Next Step
This proposal works in both single-segment and multi-segment cases
Like to
Continue to gather feedback
Iron out the details with others
Make this into a WG Working Document
THANK YOU ALL