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Catalyst 6509-E VSS Configuration

There are two Catalyst 6509-E switches with two Supervisor 720 modules on each of them. I need both supervisor uplinks to become VSL links, so i have configured Ten5/4 - 5 and Ten6/4 - 5 (these ports are on Supervisor modules) as VSL links, where:

          (SW1)Ten5/4 --> (SW2)Ten5/4;

          (SW1)Ten5/5 --> (SW2)Ten6/4;

          (SW1)Ten6/4 --> (SW2)Ten5/5;

          (SW1)Ten6/5 --> (SW2)Ten6/5;

After configuring all necessary commands for VSS supervisors have rebooted but there is no VSS, switches are still separate. IOS version is 12.2(33)SXI2a. What can be the problem?

VIP Expert

Re: Catalyst 6509-E VSS Configuration

Using ports from the sup module for VSL is fine.

Can you provide the relevant config?

Also did you try following this doc?


Re: Catalyst 6509-E VSS Configuration

I have referred to that doc, I've also watched this video

and have done everything like this guy. It's working for this guy but not for me. Does anyone configured VSS using dual supervisors and Cisco IOS 12.2(33)SXI2a ?

VIP Expert

Re: Catalyst 6509-E VSS Configuration

Quad sup is support starting IOS SXI4 or later.  SXI2a does not.

The first thing I would do is to use one sup per device and see if you can get it working.

With the current version of the IOS 2 sup per box does not provide any extra redundancy anyway.


Re: Catalyst 6509-E VSS Configuration


Are you using a single sup in each chassis? As Reza mentioned, quad supervisors (so two sups in each chassis) is not supported until SXI4. It sounds as though you are just using a single supervisor in each chassis though, for a total of two supervisors in the VSS.

Can you provide the running-config you used, or atleast the VSS related configuration from each switch? If the switches are not coming up in a VSS, it's usually one of two things: 1) One of the switches does not know it's switch number 2) The VSL is down.

The switch number is configured in the initial configuration of the VSS. However, it's actually stored in a ROMMON variable, such as "Switch_Number=1". In a working VSS, you could actually break into the ROMMON when the switch processer is booting, and see that variable. From IOS, you can do the command "switch read switch_num local" and it should show you the switch number.

If you need help, don't hesitate to open a TAC case. We work with VSS day in and day out, so it may  be something where we can spot the issue fairly quickly for you, and could potentially save you some time 

David Kosich

Cisco TAC

LAN Switching


Re: Catalyst 6509-E VSS Configuration

I agree with Reza

Quad sup support is only with SXI4 or later. The concepts of In chassis standby and In chassis active for VSS is brought in SXI4 version...


Re: Catalyst 6509-E VSS Configuration

I have configured VSS with one supervisor engine per switch and it works, so it seems I need to upgrade the IOS. There appeared new problem: now all leds of active supervisor are green and all leds of standby supervisor are amber. When consoling to standby sup it is in ROMMON mode. And when issuing "redundancy force-switchover" command on active sup it doesnt works and the "sh module" command displays "Not applicable" in the line of Module 6 (standby sup). What could be the problem?

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