End-To-End Fault Detection And Vlacp - Avaya 8800 Planning And Engineering

event of a single fiber strand break, one of the two devices may not detect a fault, and continues
to transmit data even though the far-end device does not receive it.
Table 18: 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) 2-port SFP GBIC MDA (AL2033016)
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
page 57).

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
Planning and Engineering — Network Design
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)
End-to-end fault detection and VLACP
Physical layer redundancy
on
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