1. Segment Protection Models
M Vinod Kumar
Dr. Abhay Karandikar

2. Agenda Definitions and Abbreviations Prior art Possible models
Comparison of models

3. Definitions and Abbreviations
Segment: A logical management entity defined over transitive closure of bridges and LANs or linear/open chain of connected bridges
Segment Edge Bridge (SEB): The bridge that defines end point of a segment
Infrastructure Segment (IS):
Data-path Segment (DS):
BB-BEB: 3-tupple translation bridge that translates incoming TESI to outgoing TESI. At finer granularity is may also do I-SID grooming.

4. Prior Arts Eilat (May Interim) Denver (July Plenary)
Tejas presents SPS as means to solve P2MP protection
ay-Abhay-Protection-Switching-for-P2MP-0508.ppt
Denver (July Plenary)
Jointly with Huawei and Adtran
new-sultan-fast-reroute-te-0708-v02.pdf
Seoul (Sept Interim)
Huawei presents interpretations
new-sultan-segment-protection-scaling-0908-v01.pps
Nortel presents issues to address
new-martin-PBB-TE-segment-prot-0908-v01.pdf
Tejas presents case for SPS
new-Protection-Vinod-Case-for-Segment-Protection-0908-v1.pps
Dallas (Nov Plenary)
Tejas uploads document on case for SPS
new-Vinod-SegmentProtectionSwitching-1108-v01.doc
No new work prez due to Lack of time
new-martin-PBB-TE-segment-prot-1108-v00.pdf
new-sultan-segment-protection-requirements-1108-v02.pdf
New Orleans (Jan Interim)
Tejas, Nortel, Huawei, ZTE, Adtran, …

5. Segment Protection Models
Server Layer Model
Triple MAC or Mac-in-Mac-in-Mac
Triple Q or B-VID-in-B-VID or New VID-Ethertype
Segmented Domain Model
Segmented Q-in-Q
Segmented PBB-TE (B-B BEB)

6. Server Layer Models
Triple MAC
Triple Q

7. Triple MAC

8. Triple MAC (SEB in middle)
Work-IS 1 2 3 4 5
SEB
I-tagged frame
Protect-IS
IB-BEB
NMS trace route will be issue: inner
domain is invisible to outer domain-
whether it is or ?
B-tagged frame
BCB

9. Model Components When SEB is not at the BEB S-tagged frame I-comp
I-tagged
MiM frame
B-comp
B-tagged
MiM frame

10. Triple MAC (SEB at Edge)
IB-IB-BI-BI
BI-IB
Primary-IS 1 2 3 4 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB

11. Model Component When SEB is at the BEB S-tagged frame I-comp B-comp
B-tagged
frame

12. Operations and Integrity
SEB => I-comp + B-comp (Can we avoid I-comp? No)
If SEB is defined at node 4 instead of node 2 or 3 then MAC-in-MAC-in-MAC function is needed at node 4
New and complex Chip
Integrity breaks or is not applicable as original M-i-M frame acts as client layer to the Segment Server layer
1:1 PG integrity is not same as e2e service integrity
NMS trace route function has to maintain two valid routes and
Throughput decreases
Provisioning over segment cannot be done independently of e2e provisioning
This is contrary to Client and Server layer principle which assumes that provisioning in client and server are independent

13. Final Model Component When SEB is not at the BEB S-tagged frame I-comp
I-tagged
MiM frame
B-comp
B-tagged
MiM frame
When SEB is at the BEB
S-tagged
frame
I-comp
B-comp
I-comp
B-comp
B-tagged
frame

14. Forwarding Ambiguity Problem
Forwarding Ambiguity arises in the two segments given below because
forwarding in Datapath segments is based on end-to-end DA+B-VID
node 5 cannot know if fault is in link 2-3 or 3-4
Primary-IS
Primary-IS
Single Fault 1 ? 2 3 4
No Fault
Backup-IS 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB

15. No Forwarding Ambiguity
BI-IB
IB-IB-BI-BI
Primary-IS
Primary-IS 1 2 3 4
Backup-IS 5
SEB
I-tagged frame
Backup-IS
IB-BEB
There is no forwarding ambiguity as the
3-tuple is different for every segment
B-tagged frame
BCB

16. Triple Q

17. Triple Q (SEB in Middle)
Primary-IS 1 2 3 4
Additional VLAN tag
for each segment 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB

18. Model Component When SEB is not at the BEB B-tagged QiQ frame S-comp
S-tagged
QiQiQ frame
New Ethertype?

19. Triple Q (SEB at Edge) S-S S-BI Primary-IS Primary-IS 1 2 3 4
Backup-IS 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB

20. Model Component When SEB is at the BEB S-tagged frame IB-comp B-tagged
QiQ frame
S-comp
S-tagged
QiQiQ frame
New Ethertype?

21. Operations and Integrity
SEB => S-comp + S-comp
If segment is defined at node 4 instead of node 2 or 3 then Q-in-Q-in-Q function is needed
New and complex Chip
Integrity breaks or is not applicable as original M-i-M frame acts as client layer to the Segment Server layer
1:1 PG integrity is not same as e2e service integrity
Throughput decreases
NMS trace-route issue just as in Triple-MAC

22. Final Model Component When SEB is not at the BEB B-tagged QiQ frame
S-comp
S-tagged
QiQiQ frame
New Ethertype?
When SEB is at the BEB
S-tagged
frame
IB-comp
B-tagged
QiQ frame
S-comp
S-tagged
QiQiQ frame
New Ethertype?

23. No Forwarding Ambiguity
S-S
S-BI
Primary-IS
Primary-IS 1 2 3 4
Backup-IS
VIDs are different for every cascaded
segments protecting the same service 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB

24. Segmented Domain Models
Segmented Q
Segmented PBB-TE or
BB-BEB

25. Segmented Q (SEB in Middle)
Even though Segment
is not defined between 3-4
new VLAN is needed
Primary-IS 1 2 3 4
New VLAN tag
for each segment 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB

26. Model Component Internal point When SEB is not at the BEB B-tagged
MiM frame
B-comp
I-tagged
MiM frame
B-comp
B-tagged
MiM frame

27. Segmented Q (SEB at BEB)
B-I
B-B
Primary-IS
Primary-IS 1 2 3 4
New VLAN tag
for each segment
Backup-IS 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB

28. Model Component When SEB is at the BEB S-tagged frame I-comp B-comp
B-tagged
MiM frame

29. Operations and Integrity
Maintaining same end-to-end ESP-VID is impossible sometimes
B-VLAN translation => B-comp + B-comp
I-SID shall not be multiplexed or looked into
B-MAC remains same end-to-end; only VID changes
Blue VID terminates at 2 on to a protection group: PG(cyan, Red)
PG(cyan, Red) terminates on Brown VID (or on Blue to maintain ESP-VID requirements)
Integrity breaks or is not applicable as VID in original M-i-M frame changes within the Segment Domain
1:1 PG integrity is not same as e2e service integrity
Throughput does not decrease as frame size is same

30. Final Model Component Internal point When SEB is not at the BEB
B-tagged
MiM frame
B-comp
I-tagged
MiM frame
B-comp
B-tagged
MiM frame
When SEB is at the BEB
S-tagged
frame
I-comp
B-comp
B-tagged
MiM frame

31. No Forwarding Ambiguity
B-B
Primary-IS
Primary-IS 1 2 3 4
Backup-IS 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-MAC remains unchanged
so to prevent forwarding
ambiguity VID should
be different
B-tagged frame
BCB

32. Segmented PBB-TE or B-B BEB

33. Segmented PBB-TE or BB-BEB (SEB in Middle)
Irrespective of Segment
defined between 3-4
new VLAN is needed
Primary-IS 1 2 3 4
New 3-tupple
for each segment 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB

34. Model Component Internal point When SEB is at the BEB B-tagged
MiM frame
B-comp
I-tagged
MiM frame
B-comp
B-tagged
MiM frame

35. Segmented PBB-TE or BB-BEB (SEB at BEB)
B-I
B-B
Primary-IS
Primary-IS 1 2 3 4
New 3-tupple
for each segment
Backup-IS 5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB

36. Model Component When SEB is at the BEB S-tagged frame I-comp B-comp
B-tagged
MiM frame

37. Operations and Integrity
SEB => B-comp + B-comp
TESI translation, incoming TESI is mapped to outgoing TESI
At finer granularity I-SID mux-demux can also be done
Smaller PBB-TE segments interacting as peers
Integrity is not applicable as original M-i-M frame terminates and new M-i-M frame starts
PG function is same as defined in e2e service
N:1 PG to be defined
Throughput remains same

38. Final Model Component Internal point When SEB is not at the BEB
B-tagged
MiM frame
B-comp
I-tagged
MiM frame
B-comp
B-tagged
MiM frame
When SEB is at the BEB
S-tagged
frame
I-comp
B-comp
B-tagged
MiM frame

39. No Forwarding Ambiguity
B-B
Primary-IS
Primary-IS 1 2 3 4
Backup-IS 5
SEB
I-tagged frame
Backup-IS
IB-BEB
3-tupple differs from segment to
segment so there will never
arise forwarding ambiguity
B-tagged frame
BCB

40. Pros and Cons Features Triple MAC Triple Q Segmented Q
Segmented PBB-TE or BB-BEB
Best of all ?
Throughput
Lowest
Low
Same
same
Feasibility
New Chip
S-Comp
B-B comp
Forwarding Ambiguity No
Integrity issue
Not applicable
Not Applicable
Standards compliant
May be
PBB
PBB, PBB-TE
Applications
Only SPS
Yes (SPS, PBB+VPLS, I-SID aggregation, ENNI-2)
Protection Group
1:1
1:1 (Could be different VID)
1:1 (and N:M)
Processing in middle
Highest
High
High or highest
Processing at edge
Same or high

41. Questions?