I have two VLANs (20 and 21) that are accessing the same resource on a switch. Clients on VLAN 20 access this resource only at schedule times, but when they do, they generate lots of traffic as they're dumping large amounts of data. Clients on VLAN 21 need to access the resource at any time, but when VLAN 20 clients are dumping large data, VLAN 21 has slow access times.
Because I cannot relocate or replace this shared resource, I need to be able to prioritize traffic between these two VLANs. I've read several of the Cisco documents on QoS, but it seems very complicated and many times directed toward QoS for VoIP. To be honest, I'm no switch guru, but I have a good knowledge of networking and how to generally configure a switch.
Is there a simple way of configuring QoS on a Cisco 3560 switch that says "give VLAN 20 20% priority and VLAN 21 80% priority to port X"? If yes, how do you set this up?