4500x VSS Dual-Active detection

[fgasimzade]

Hello,

We have a test environment with 2 4500-x switches in VSS.

We have not configured any dual-active detection, however if we shutdown VSL links, Active switch goes to recovery mode and Standby switch becomes Active

How is it possible if no dual-active detection mechanism is configured?

[Mark Malone]

Hi

VSS failover works without the dual-active detection as you seen all that's require in VSL setup between pair   , dual active detection just prevents bot sups frm becoming active , if the VSL fails it initiates a failover but if the chassis is ok and dual-active is not in place you could end up with 2 active chassis causing an issue rather than an active standby which is whats expected after a failover

[fgasimzade]

The thing is that Active switch goes into recovery when I shutdown ALL VSL links, it does not stay in active mode. So I dont really understand how both switches can become active

[Mark Malone · Accepted solution]

The docs say it can go into active /active mode it doesn't say it always will but with dual enabled it will protect it from that , its a good thing it has not gone onto active /active that means switch was able to work correctly in VSS mode though VSL without it enabled but I would still enable it as its best practice before it goes prod