8800/8600 Switch Fabric HA vs Non-HA Configuration

[Stefan Herbst]

I was reading another post that led me to this topic...

Configuring the 8800/8600 CPU's in HA vs Non-HA (warm standby). Here is my take on the two modes;
1. HA - Both CPU's are in an active/active state, protocol convergence and forwarding tables are synced real time.
2. Non-HA (warm standby) - The primary CPU is the only 'active' CPU. If a fail-over occurs the backup CPU will boot, protocols and forwarding tables will be relearned.

I know in the past (older code versions) a number of feature sets were not supported. I had a look at the admin guide for 7.1.1 and the feature support is much better. I was wondering how many people are running in HA mode vs. Non-HA? If anyone has run into issues/nuances/bugs related to a CPU HA config? Reasons for configuring one over another (other than the obvious)?


Stefan
@exactnetworks

[Dave]

We have like 20 8800/8600 chassis aat the moment and we are running them with HA-mode enabled.

I would advise running 5.1.7.x or 7.1.1.x though. I was told that in pre 5.1.5 releases there were some issues with the backup CPU not realizing that the primary was malfunctioning and was not taking over at all, but personally I was not working with avaya/nortel tech back then...

We run both 5.1.7 and 7.1.1 in our productive networks without issues....

[Dominik]

The non-HA config for 2 CPU modules was first introduced, to have a failover in one chassis.

Down sides:
-long failover time , in fact the stanby makes a complete boot during a failover event.
Upsides:
-all features are enabled, in fact both CPU modules work seperatly.

Later the HA mode was introduced, in the 3.7.x 4.0.x and 4.1 there where not the full feature support
in the HA mode. Not 100% sure, but I think in 7.1 sw release there are no limitations for HA mode.

Downside:
-some features does not work on older SW version

Upside:
-fast failover
-no coldstart is needed for the stanby CPU module

I think if you run 7.1.x SW it is the better choice to run HA mode instead of non-HA.

Good Luck

[ChesTrulson]

We haven't played with HA for some time now, but it was nothing but trouble when we did.  Lots of core dumps.  The loss of reliability greatly out-weighed the benefits.  I have heard that HA mode on the VSP9000s is much better though, and it sounds like HA in 7.1 might be a bit better too.  It might be time to have another look.

[Dominik]

@Ches

since SW 5.1 the HA mode works pretty stable and support all features.
I had also bad expirience with old SW versions and HA, but the devollopers made here a big step forward.