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New Member

VSS Dual active detection

Does the PAgP mode working with Nortel as access switches.

(The symptom is that when the VSL link is down both switches working as a active , when the vsl came back the switches recognize dual active and the backup switch disable all non vsl ports)

New Member

Re: VSS Dual active detection


The dual active detection you described is supported by enhanced PAgP, which is only supported by newer versions of IOS on certain CISCO switches.

It doesn't work w/ Nortel switches.

Even regular PAgP doesn't work w/ non-Cisco switches.(most of them don't support it)

This should be in the LAN switching section instead of application anyway.

New Member

Re: VSS Dual active detection

Do you have experience with VSS in distributed mode ( Switches placed in different location), mainly about the dual active detection method

New Member

Re: VSS Dual active detection

You mean one VSS member switch in one datacenter, and the other member switch in the second datacenter?

I wouldn't recommend doing VSS across WAN/MAN.

Remember the dual active detection using enhanced PAgP is done through downstream switches that have MEC to the VSS chassis'.

This means one link goes to the local VSS member switch, and the other link would go through the WAN, onto the other VSS member switch.

Also, the main benefit of doing VSS is to cut down your spanning-tree domain.

To really take advantage of that you'd have uplinks from downstream switches to both VSS member switches across WAN/MAN, which just isn't an efficient way to mesh your switches.

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