port spanning from multiple source switchports to 1x destination switchport

[donnie]

Hi all,

I like to know if there will be any impact (if it would affect my switch performance or cause my switch to be unstable) to my cisco 6500E core switch if i were to configure port mirroring where traffic is spanned from 8x source switchports to 1x destination switchport. All my switchports are running 1Gbps bandwidth and the traffic utilisation is typically 300Mbps for my source switchports during office hours hence i would expect some drop traffic during port spanning. But will this port spanning activity cause my Cisco 6500E core switch to be unstable? Pls advise. TIA!

[brselzer · Accepted solution]

Hello Donnie,

This should be fine. The thing to take into account here is that you have a backplane between linecards. There are usually 2x20Gbps channels to transfer traffic from linecard to linecard. If you span too much traffic to one linecard (20+ 1gig interfaces or multiple 10gig interfaces), you run the risk of overloading the backplane. You can monitor this with the command "show fabric utilization". 

However, with this setup, the worst you will probably see is some drops on your span destination which won't impact your traffic at all, it just might mean your capture is incomplete.

Hope that helps!