I’ve seen quite a few issues with VLACP on the Nortel Ethernet Routing Switches but now Nortel has released a technical bulletin documenting a known issue when running VLACP on their stackable switches (ERS2500, ERS4500, ERS5500, ERS5600) with their chassis based ERS8300 and ERS8600 switches.

The bulletin advises users to re-configure the VLACP timeout from a default value of 3 to 5.

5520-48T-PWR(config)#interface fastEthernet 5-6
5520-48T-PWR(config-if)#vlacp timeout-scale 5
5520-48T-PWR(config-if)#show vlacp interface 5-6
===============================================================================
VLACP Information
===============================================================================
PORT ADMIN OPER HAVE FAST SLOW TIMEOUT TIMEOUT ETH MAC
ENABLED ENABLED PARTNER TIME TIME TYPE SCALE TYPE ADDRESS
-------------------------------------------------------------------------------
5 true true yes 500 30000 short 5 8103 00:00:00:00:00:00
6 true true yes 500 30000 short 5 8103 00:00:00:00:00:00

The bulletin also refers to a software fix in ERS 2500 v4.2.1, ERS4500 v5.2.1 and ERS5500/5600 v6.0.2 or later maintenance releases.

We really only use VLACP as a means of detecting FEFI when the switch equipment doesn’t support autonegotiation (example; Nortel Ethernet Switch 470 doesn’t support autonegotiation on the 1000Mbps uplinks).

Cheers!

Update: Friday February 13, 2009

It seems that Nortel has released software 6.0.3 for the Ethernet Routing Switch 5500/5600 series switches. This release is suppose to resolve the VLACP issues that were reported in the earlier bulletin. Here’s an excerpt from the release notes;

A feature enhancement (Q01645430) that changed the VLACP interoperability behavior with Passport 8600 was removed. For further details, please see the Technical Support Bulletin ID. 2008009238, Rev 1, published on 2008-12-12.

Cheers!