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Enhancements to Ethernet AIS
David Elie Dit Cosaque, Kamakshi Sridhar,
Maarten Vissers, Tony Van Kerckhove
Introduction
>
Proposals for essential EthAIS functions
>
EthAIS Coalescing
>
EthAIS accurate alarm suppression
IEEE 802.1 July 11-16, 2004 — 2
Problem I: EthAIS cascading
C1
Two EthAIS
received
1
2
3
4
C2
1
2
3
4
PE3
CE1
PE1
P2
1
2
1
2
3
4
3
4
CE2
PE2
Fault2
P1
1
2
3
4
1
2
3
4
CE3
1
2
1
2
3
4
3
4
P3
1
2
1
2
1
2
3
4
3
4
3
4
PE4
Fault1
CE4
1
2
1
2
3
4
3
4
Multiple lower level faults result in multiple EthAIS
>Excessive bandwidth consumption
IEEE 802.1 July 11-16, 2004 — 3
Solution: EthAIS Coalescing
>
Solution: coalesce EthAIS in the MPs.
•
Multiple faults at lower levels are seen as a single fault
by higher levels
• Edge MP’s will generate a new AIS with a different
sequence number.
Benefits:
>The bandwidth taken by EthAIS at each level is
independent of the number of faults at lower levels
>No change in AIS frame format required.
IEEE 802.1 July 11-16, 2004 — 4
Example: EthAIS coalescing
C1
1
2
3
4
PE3
CE1
One EthAIS
received
C2
1
2
3
4
PE1
P2
1
2
1
2
3
4
3
4
CE2
1
3
2
4
PE2
1
Fault2
P1
1
2
3
4
2
3
1
2
3
4
3
2
2
1
2
3
4
3
4
1
2
1
2
3
4
3
4
PE4
4
Fault1
Regenerated
1
P3
1
4
CE3
CE4
LP
CCLoss
MP
Terminated
Effectively solves the cascading problem without
requiring AIS frame format change
IEEE 802.1 July 11-16, 2004 — 5
Problem II: EthAIS Alarm suppression inaccuracies
ME { MP5, MP1}
CCLoss 1
CCLoss suppressed
1
3
C2
MP1
MP2
2
1
4
3
CE1
PE3
PE1
2
1
2
1
4
3
4
3
MP5
P1
2
1
2
1
3
4
3
2
4
Link Fault1
4
MP3
Fabric Fault2
PE4
CCLoss
2 suppressed
CCLoss
2
This must be alarmed
CE3
ME { MP5, MP4}
1
2
1
3
4
3
CE4
2
1
4
3
C1
2
4
MP4
> Link failure alarms raised at server level, so CC loss alarm at any
other level must be suppressed.
>
However, don’t want to suppress a CC loss due to customer
fabric failure, because it is the only way to detect fabric faults.
>
A mechanism to selectively alarm fabric failure CCLoss needed
IEEE 802.1 July 11-16, 2004 — 6
Solution: TLV in AIS frame
ME { MP5, MP1}
CCLoss 1
MP1
MP2
CCLoss suppressed
C2
CE3
PE3
CE1
1
2
1
2
3
4
3
4
MP5
PE1
MP1
1
2
1
3
4
3
4
P1
1
2
1
2
3
4
3
4
Link Fault1
MP3
Fabric Fault2
PE4
CCLoss NOT
suppressed
suppressed
CCLoss 2
2
ME { MP5, MP4}
CE4
C1
1
2
1
2
1
2
3
4
3
4
3
4
MP4
>
>
>
>
EthAIS indicates which upper level MPs (MP1) are affected by a CCLoss
Stored in a data base at edge MP’s (Learning phase)
New TLV in EthAIS containing MP1
MP suppress CCLoss from MEs indicated in the EthAIS TLV (AIS TLV
phase)
IEEE 802.1 July 11-16, 2004 — 7
Implementation: EthAIS database
Indicates which customer MPs are behind provider MPs
>
Provider
Customer MPs behind it
MP
CE1
MP 1
PE1
1
2
1
2
3
4
3
4
MP3
MP 2
--MP 44
MP 24
MP 28
---
---
---
EthAIS database in MP 3
IEEE 802.1 July 11-16, 2004 — 8
How is the TLV (MP1) generated for AIS?
CC Database
CC
CC
MP1->
-----
LP3
LP2
TLV
EthAIS
database
MP2 MP1->
-----
MP2
MP3
MP1
Port 2
PE3
Port 3
1
C1
1
2
3
4
C2
1
3
2
1
2
3
4
CC
3
CE1
PE1
4
P1
1
2
1
2
1
2
3
4
3
4
3
4
2
4
CE3
MP3
MP2
PE4
CE4
1
2
1
2
3
4
3
4
>
MP1 is learnt from green CC.
>
MP1 is installed in blue CC to populate the EthAIS database in MP3
>
Additional
TLV in CC frames
IEEE 802.1 July 11-16, 2004 — 9
Summary
+We propose:
+a new Ethernet Coalescing scheme.
+One AIS generated for multiple lower level faults.
+a scheme for EthAIS accurate alarm
suppression.
+Allows for CC loss due to fabric failures to be
alarmed, inspite of EthAIS.
+EthAIS indicates unreachable upper level end
point MP’s
IEEE 802.1 July 11-16, 2004 — 10
www.alcatel.com
IEEE 802.1 July 11-16, 2004 — 11
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