Prioritizing switch resources per VLAN

fdouble08 · ‎11-20-2009

I have seen a lot of documentation and most of what I've read is somewhat confusing. Hopefully someone here can explain or direct me to helpful documentation that will help me accomplish my desired config.

I have several VLANs in my network, one particular VLAN is critical to production and should have priority ( cpu resource, trunk bandwidth, and switching ) over all other VLANs. My switches are all Cisco 3560G's. The critical VLAN has no L3 interface. This is to prevent any external networks from introducing traffic. The trunks between switches carry all VLANs, so I need to configure them to give the critical VLAN priority over all other VLANs. I also need to make sure that the switch's CPU resources can not get consumed by traffic on another VLAN (broadcast storm, ping of death, etc.) that could result in a denial of service for the critical VLAN.

Can someone provide an example of how to do this or direct me to where I can find an example of this configuration?

Thanks!

Giuseppe Larosa · ‎11-25-2009

Hello,

unfortunately it is not possible to dedicate resources to a specific Vlan traffic or to give it priority to its frames only because they belong to a specific vlan-id.

However, you can use QoS with the diffserv approach: if you are able to mark frames belonging to the critical vlan with a specific DSCP and 802.1p values you can give a better treatment to these frames on all trunk ports in your campus.

regarding protection from possible bridging loops combining STP loop guard, broadcast storm-control and eventually UDLD helps but it is not a guarantee that this kind of events will never happen.

Hope to help

Giuseppe