VSS SVI Utilisation

[patrick.roche]

Hello,

I was wondering if someone could answer the following question for me:

I'm seeing SVI interfaces hit 160% utilisation on some of our 6509 switches.

As these switches are in a VSS setup, is the utilisation effectively divided by the two VSS switches and if so, would it be good practise to say configure the SVI interfaces
with 2Gb bandwidth statements as opposed to the default of 1Gb?

Regards,

Pat

[Reza Sharifi]

Hi Pat,

Watch out for high CPU utilization, specially if you are running a modular code.  In VSS the 6500 logically become one switch and the config applies  to the entire system not to one switch.  So, I don't think changing SVI bandwidth has any effect.  Monitor  the CPU, and if it is not high, you should be fine.

HTH

[Rahul Kachalia]

Hello Pat,

VSS only divides forwarding-plane for optimal switching. Logically it is a single switch to control and manage which is handled by SSO-ACTIVE supervisor that may be current on Switch-1 or Switch-2.

VSS solves technical challenge by virtualizing two physical systems deployed in same common network layer and in common role. When it is deployed with best practices, you should not see increase on interfaces compared to Standalone design. I recommend you reading Chapter 2 of following Design Guide that shares best practices to minimize control-plane usage, improve forwarding-plane capacity and build more resilient network design independent of network tier - Core or Aggregation :

Borderless Campus 1.0 Design Guide

SVI is an logical interface, capacity is derived from where the VLAN is associated to physical interface and not the logical...

thanks,

rahul.