End-To-End Fault Detection And Vlacp - Avaya 8800 Planning And Engineering, Network Design

Table 17: Ethernet switching devices that do not support autonegotiation
Switch name / Part number
Ethernet Switch 470-48T (AL2012x34) Ethernet Switch
470-24T (AL2012x37)
Ethernet Switch 460-24T-PWR (AL20012x20)
OM1200 (AL2001x19)
OM1400 (AL2001x22)
OM1450 (AL2001x21)
If you must connect the switch to a device that does not support autonegotiation, you can use
Single-fiber Fault Detection (SFFD). SFFD can detect single fiber faults and bring down faulty links
immediately. If the port is part of a multilink trunk (MLT), traffic fails over to other links in the MLT
group. Once the fault is corrected, SFFD brings the link up within 12 seconds. For SFFD to work
properly, both ends of the fiber connection must have SFFD enabled and autonegotiation disabled.
A better alternative to SFFD is VLACP (see

End-to-end fault detection and VLACP

A major limitation of the RFI and FEFI functions is that they terminate at the next Ethernet hop.
Therefore, failures cannot be determined on an end-to-end basis over multiple hops.
To mitigate this limitation, Avaya has developed a feature called Virtual LACP (VLACP), which
provides an end-to-end failure detection mechanism. With VLACP, far-end failures can be detected.
This allows MLT to properly failover when end-to-end connectivity is not guaranteed for certain links
in an aggregation group.
VLACP allows you to switch traffic around entire network devices before Layer 3 protocols detect a
network failure, thus minimizing network outages.
VLACP operation
Virtual Link Aggregation Control Protocol (VLACP) is an extension to LACP used for end-to-end
failure detection. VLACP is not a link aggregation protocol, but rather a mechanism to periodically
check the end-to-end health of a point-to-point connection. VLACP uses the Hello mechanism of
LACP to periodically send Hello packets to ensure an end-to-end communication. When Hello
packets are not received, VLACP transitions to a failure state, which indicates a service provider
failure and that the port is disabled.
The VLACP only works for port-to-port communications where there is a guarantee for a logical port-
to-port match through the service provider. VLACP does not work for port-to-multiport
communications where there is no guarantee for a point-to-point match through the service provider.
You can configure VLACP on a port.
June 2016
Port or MDA type / Part number
SX GBIC (AA1419001)
LX GBIC (AA1419002)
XD GBIC (AA1419003)
ZX GBIC (AA1419004)
2-port SFP GBIC MDA (AL2033016)
2-port SFP GBIC MDA (AL2033016)
2-port SFP GBIC MDA (AL2033016)
2-port SFP GBIC MDA (AL2033016)
End-to-end fault detection and VLACP
Planning and Engineering — Network Design
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Physical layer redundancy
on page 57).
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