Segment Protection Models
M Vinod Kumar
Dr. Abhay Karandikar
1
Agenda
•
•
•
•
Definitions and Abbreviations
Prior art
Possible models
Comparison of models
2
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.
3
Prior Arts
•
Eilat (May Interim)
–
Tejas presents SPS as means to solve P2MP protection
•
•
Denver (July Plenary)
–
Jointly with Huawei and Adtran
•
•
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-sultan-fast-reroute-te-0708-v02.pdf
Seoul (Sept Interim)
–
•
ay-Abhay-Protection-Switching-for-P2MP-0508.ppt
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, …
4
Segment Protection Models
• Server Layer Model
– Triple MAC or Mac-in-Mac-in-Mac
– Triple Q or B-VID-in-B-VID or New VIDEthertype
• Segmented Domain Model
– Segmented Q-in-Q
– Segmented PBB-TE (B-B BEB)
5
Server Layer Models
1. Triple MAC
2. Triple Q
6
Triple MAC
7
Triple MAC (SEB in middle)
Work-IS
1
2
3
4
5
SEB
I-tagged
frame
B-tagged
frame
Protect-IS
NMS trace route will be issue: inner
domain is invisible to outer domainwhether it is 1-2-3-4 or 1-2-5-3-4?
IB-BEB
BCB
8
Model Components
When SEB is not at the BEB
S-tagged
frame
I-tagged
MiM frame
I-comp
B-tagged
MiM frame
B-comp
9
Triple MAC (SEB at Edge)
IB-IB-BI-BI
BI-IB
Primary-IS
1
2
3
4
5
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
IB-BEB
BCB
10
Model Component
When SEB is at the BEB
S-tagged
frame
B-tagged
frame
I-comp
B-comp
I-comp
B-comp
11
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-inMAC-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 1-2-3-4 and 12-5-3-4
• 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
12
Final Model Component
When SEB is not at the BEB
S-tagged
frame
I-tagged
MiM frame
I-comp
B-tagged
MiM frame
B-comp
When SEB is at the BEB
S-tagged
frame
B-tagged
frame
I-comp
B-comp
I-comp
B-comp
13
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
1
Single Fault
No Fault
2
3
5
?
4
Backup-IS
?
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
IB-BEB
BCB
14
No Forwarding Ambiguity
IB-IB-BI-BI
BI-IBPrimary-IS
Primary-IS
1
2
3
4
Backup-IS
5
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
There is no forwarding ambiguity as the
3-tuple is different for every segment
IB-BEB
BCB15
Triple Q
16
Triple Q (SEB in Middle)
Primary-IS
1
2
3
4
Additional VLAN tag
for each segment
5
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
IB-BEB
BCB
17
Model Component
When SEB is not at the BEB
B-tagged
QiQ frame
S-tagged
QiQiQ frame
S-comp
New Ethertype?
18
Triple Q (SEB at Edge)
S-S Primary-IS
Primary-IS
1
2
3
S-BI
4
Backup-IS
5
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
IB-BEB
BCB
19
Model Component
When SEB is at the BEB
S-tagged
frame
IB-comp
B-tagged
QiQ frame
S-tagged
QiQiQ frame
S-comp
New Ethertype?
20
Operations and Integrity
• SEB => S-comp + S-comp
• If segment is defined at node 4 instead of node 2 or 3 then Q-in-Qin-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
21
Final Model Component
When SEB is not at the BEB
B-tagged
QiQ frame
S-tagged
QiQiQ frame
S-comp
New Ethertype?
When SEB is at the BEB
S-tagged
frame
IB-comp
B-tagged
QiQ frame
S-tagged
QiQiQ frame
S-comp
New Ethertype?
22
No Forwarding Ambiguity
S-S Primary-IS
Primary-IS
1
2
3
S-BI
4
Backup-IS
5
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
VIDs are different for every cascaded
segments protecting the same service
IB-BEB
BCB 23
Segmented Domain Models
1. Segmented Q
2. Segmented PBB-TE or
BB-BEB
24
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
B-tagged
frame
Backup-IS
IB-BEB
BCB
25
Model Component
Internal point
When SEB is not at the BEB
B-tagged
MiM frame
I-tagged
MiM frame
B-comp
B-tagged
MiM frame
B-comp
26
Segmented Q (SEB at BEB)
B-B
Primary-IS
Primary-IS
1
2
3
New VLAN tag
for each segment
B-I
4
Backup-IS
5
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
IB-BEB
BCB
27
Model Component
When SEB is at the BEB
S-tagged
frame
B-tagged
MiM frame
I-comp
B-comp
28
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
29
Final Model Component
Internal point
When SEB is not at the BEB
B-tagged
MiM frame
I-tagged
MiM frame
B-comp
B-tagged
MiM frame
B-comp
When SEB is at the BEB
S-tagged
frame
B-tagged
MiM frame
I-comp
B-comp
30
No Forwarding Ambiguity
B-B
Primary-IS
Primary-IS
1
2
3
B-I
4
Backup-IS
5
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
B-MAC remains unchanged
so to prevent forwarding
ambiguity VID should
be different
IB-BEB
BCB
31
Segmented PBB-TE or
B-B BEB
32
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
B-tagged
frame
Backup-IS
IB-BEB
BCB
33
Model Component
Internal point
When SEB is at the BEB
B-tagged
MiM frame
I-tagged
MiM frame
B-comp
B-tagged
MiM frame
B-comp
34
Segmented PBB-TE or
BB-BEB (SEB at BEB)
B-B
Primary-IS
Primary-IS
1
2
3
New 3-tupple
for each segment
B-I
4
Backup-IS
5
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
IB-BEB
BCB
35
Model Component
When SEB is at the BEB
S-tagged
frame
B-tagged
MiM frame
I-comp
B-comp
36
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
37
Final Model Component
Internal point
When SEB is not at the BEB
B-tagged
MiM frame
I-tagged
MiM frame
B-comp
B-tagged
MiM frame
B-comp
When SEB is at the BEB
S-tagged
frame
B-tagged
MiM frame
I-comp
B-comp
38
No Forwarding Ambiguity
Primary-IS
1
2
B-I
B-B
Primary-IS
3
4
Backup-IS
5
SEB
I-tagged
frame
B-tagged
frame
Backup-IS
3-tupple differs from segment to
segment so there will never
arise forwarding ambiguity
IB-BEB
BCB
39
Pros and Cons
Triple MAC
Triple Q
Segmented Q
Segmented PBB-TE
or BB-BEB
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,
PBB+VPLS, I-SID
aggregation, ENNI-2)
Protection
Group
1:1
1:1
1:1 (Could be
different VID)
1:1 (and N:M)
Processing in
middle
Highest
High
High
High or highest
Processing at
edge
Highest
High
Same
Same or high
Features
Best of
all ?
40
Questions?
41