VSS Redundancy Question VSL Link

Unanswered Question
Apr 23rd, 2010

The question I have is related to VSS redundancy.

Setup:

2 6509 VE Chassis with SUP 720.

We have 2 10 Gigabit links to each switch for VSS/VSL traffic.

One connection is on the SUP itself and the other is on a WS-X6716-10G-3C module.

We have connections on etherchannels on both switches going to other Cisco devices via 10 Gigabit.

The question is, if we removed one of the reduandant connections going to a edge switch, would VSS/VSL act funny?

I have this problem too.
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Bobby Thekkekandam Fri, 04/23/2010 - 08:03

If I understand you correctly, you have your edge devices dual homed to the VSS pair via a Multichassis EtherChannel (MEC).

If you remove one of the links, the VSS will not be affected, but you do lose redundancy as well as cutting your bandwidth between the VSS pair and the edge switch in half.

The best practice, of course, is to dual home all devices to the VSS pair, but it is certainly valid to single home devices as well, though not ideal.

Hope that helps,

Bobby

carl.wertz Tue, 04/27/2010 - 08:50

The edges are dual homed to the VSS cores.

The question I have is, if we remove one of the links from the edges to the cores, would the other VSS chassis cause some issue on the network?

Reza Sharifi Tue, 04/27/2010 - 09:10

carl.wertz wrote:

The edges are dual homed to the VSS cores.

The question I have is, if we remove one of the links from the edges to the cores, would the other VSS chassis cause some issue on the network?

Carl,

That would not cause any issues with VSS.  You only loose one of your uplinks from the Etherchannel bundle.

HTH

Reza

carl.wertz Tue, 04/27/2010 - 09:11

OK, have you tested this or how confident are you?  Trying to get people to beleive

this is not an issue.

Reza Sharifi Tue, 04/27/2010 - 09:20

I have tested this meany times. It will not cause any issue with VSS.  As a matter of fact if you are using that specific port for forwarding traffic and you disconnected, the only data you loose is what is already on the wire.

HTH

Reza

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