Segment Protection Models

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)
• 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-0
  908-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-v0
  2.pdf

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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

1. Triple MAC
2. Triple Q

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Triple MAC
8
Triple MAC (SEB in middle)
Work-IS
1
4
3
2
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 1-2-3-4
or 1-2-5-3-4?
B-tagged frame
BCB
9
Model Components
When SEB is not at the BEB
I-comp
B-comp
S-tagged frame
I-tagged MiM frame
B-tagged MiM frame
10
Triple MAC (SEB at Edge)
IB-IB-BI-BI
BI-IB
Primary-IS
1
4
3
2
5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB
11
Model Component
When SEB is at the BEB
I-comp
B-comp
S-tagged frame
B-tagged frame
I-comp
B-comp
12
Operations and Integrity

• SEB gt 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
• 11 PG integrity is not same as e2e service
  integrity
• NMS trace route function has to maintain two
  valid routes 1-2-3-4 and 1-2-5-3-4
• 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
I-comp
B-comp
S-tagged frame
I-tagged MiM frame
B-tagged MiM frame
When SEB is at the BEB
I-comp
B-comp
S-tagged frame
B-tagged frame
I-comp
B-comp
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Forwarding Ambiguity Problem

• Forwarding Ambiguity arises in the two segments
  given below because
• forwarding in Datapath segments is based on
  end-to-end DAB-VID
• node 5 cannot know if fault is in link 2-3 or 3-4

Primary-IS
Primary-IS
1
4
3
2
Backup-IS
5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB
15
No Forwarding Ambiguity
Primary-IS
Primary-IS
1
4
3
2
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
4
3
2
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
S-comp
B-tagged QiQ frame
S-tagged QiQiQ frame
New Ethertype?
19
Triple Q (SEB at Edge)
Primary-IS
Primary-IS
1
4
3
2
Backup-IS
5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB
20
Model Component
When SEB is at the BEB
IB-comp
S-comp
S-tagged frame
S-tagged QiQiQ frame
B-tagged QiQ frame
New Ethertype?
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Operations and Integrity

• SEB gt 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
• 11 PG integrity is not same as e2e service
  integrity
• Throughput decreases
• NMS trace-route issue just as in Triple-MAC

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Final Model Component
When SEB is not at the BEB
S-comp
B-tagged QiQ frame
S-tagged QiQiQ frame
New Ethertype?
When SEB is at the BEB
IB-comp
S-comp
S-tagged frame
S-tagged QiQiQ frame
B-tagged QiQ frame
New Ethertype?
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No Forwarding Ambiguity
S-BI
Primary-IS
Primary-IS
1
4
3
2
Backup-IS
5
SEB
I-tagged frame
Backup-IS
IB-BEB
B-tagged frame
BCB
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Segmented Domain Models

• Segmented Q
• Segmented PBB-TE or
• BB-BEB

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Segmented Q (SEB in Middle)
Even though Segment is not defined between
3-4 new VLAN is needed
Primary-IS
1
4
3
2
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-comp
B-comp
B-tagged MiM frame
I-tagged MiM frame
B-tagged MiM frame
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Segmented Q (SEB at BEB)
B-I
B-B
Primary-IS
Primary-IS
1
4
3
2
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
I-comp
B-comp
S-tagged frame
B-tagged MiM frame
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Operations and Integrity

• Maintaining same end-to-end ESP-VID is impossible
  sometimes
• B-VLAN translation gt 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
• 11 PG integrity is not same as e2e service
  integrity
• Throughput does not decrease as frame size is same

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Final Model Component
Internal point
When SEB is not at the BEB
B-comp
B-comp
B-tagged MiM frame
I-tagged MiM frame
B-tagged MiM frame
When SEB is at the BEB
I-comp
B-comp
S-tagged frame
B-tagged MiM frame
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No Forwarding Ambiguity
B-I
B-B
Primary-IS
Primary-IS
1
4
3
2
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
4
3
2
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-comp
B-comp
B-tagged MiM frame
I-tagged MiM frame
B-tagged MiM frame
35
Segmented PBB-TE or BB-BEB (SEB at BEB)
B-I
B-B
Primary-IS
Primary-IS
1
4
3
2
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
I-comp
B-comp
S-tagged frame
B-tagged MiM frame
37
Operations and Integrity

• SEB gt 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
• N1 PG to be defined
• Throughput remains same

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Final Model Component
Internal point
When SEB is not at the BEB
B-comp
B-comp
B-tagged MiM frame
I-tagged MiM frame
B-tagged MiM frame
When SEB is at the BEB
I-comp
B-comp
S-tagged frame
B-tagged MiM frame
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No Forwarding Ambiguity
B-I
B-B
Primary-IS
Primary-IS
1
4
3
2
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
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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 New Chip S-Comp B-B comp
Forwarding Ambiguity No No No No
Integrity issue Not applicable Not applicable Not Applicable Not applicable
Standards compliant No May be PBB PBB, PBB-TE
Applications Only SPS Only SPS Only SPS Yes (SPS, PBBVPLS, I-SID aggregation, ENNI-2)
Protection Group 11 11 11 (Could be different VID) 11 (and NM)
Processing in middle Highest High High High or highest
Processing at edge Highest High Same Same or high
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Questions?