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New Member

I seek knowledge: QoS, multi-vlan, multi-switch environment


I'm trying to get my head around QoS.. I have this situation:

3750X (switch1)

3750G (switch2) (VOD, vlan 2)

3750 (switch3) (Controllers, vlan 3)

switch2 and switch3 are linked to the switch1, which is doing routing.

I need to prioritize the traffic of the the Controllers, so that however much traffic is produced by the VOD, the controlling packets of the controllers to the VOD have always precedence.

I've read about the LLQ.. but how can one apply that to the situation above?

I have experience with cisco IOS for routers and switches, but QoS is new to me.

pointers are welcome..



  • LAN Switching and Routing
Everyone's tags (2)
Cisco Employee

I seek knowledge: QoS, multi-vlan, multi-switch environment

Hi Thomas,

In this you need to make sure that you controllers control traffic is basically either mapped to Priority queue or has a higher drop threshold if they are mapped to the same queue. If controllers control plane traffic is in a different queue than VOD, you have to make sure that you have a higher drop threshold for it in a specific queue.

I have used Campus Medianet QOS design guide in the past to design QOS policies for customers. Please have a look at it.

Hope this helps.


-amit singh

New Member

I seek knowledge: QoS, multi-vlan, multi-switch environment

Hi Amit..

Thank you for that link.. very interesting read, although quite complex.. I'll have to go through there a few times, wrap my head around it..