Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
Community Member


hi! I've a stack of 4 cisco3524(IOS) switches with 2 of these switches (the bottom and the top) connected to the 2 core switches (6509-CatOS) by fiber link.

I noticed that both of these interfaces connected to the core switches are in forwarding state. I would like to have one of them as a standby and not forwarding traffic for both. The reason is because i noticed that one of the link is not that stable, there are intermittent packet lost. So, i would like all the traffic to go to the other fiber link and the one with problem as standby.

What need to be done to achieve this? Btw how do i check whether the link with intermittent problem is it caused by the hardware or something else. From the interface it will show link and protocol up, but when i do a continous ping to other devices outside of the 4 edge switches, there's intermittent timeout.

Please advise. Thanks.

Hall of Fame Super Blue

Re: switching


Are your 6500 core switches connected to each other via L2 trunk ?

If they are and the vlans are the same across all your 3524 switches then if both links are forwarding they must be being blocked somewhere else. Have you set STP root and secondary for your vlans on the 6500 switches ?

Attached is a troubleshooting doc on interface problems which may give you some pointers.


CreatePlease to create content