Limit-Bandwidth

Bandwidth command won't do you much good. it's only used for metrics, not actual limiting.

You're going to have to do some QoS with shaping commands. Here's a sample from one of my switches. You will have to do it on your router, and the router has more capabilities than my switch, but here's a start for you.

It'll probably be better for you to do a nested QoS. Limit the whole interface for 5Mb, then do another QoS layer with your important VLAN as priority, then leave the class default as is.

Anyways, check out my config below so you can see how I'm shaping my traffic, but then create one yourself by following the guide below.

http://www.cisco.com/en/US/docs/ios/12_2/qos/configuration/guide/qcfpolsh.html


interface GigabitEthernet0/0
 bandwidth 4096
 service-policy output VZ-traf-shaping


policy-map VZ-traf-shaping
 class Voice-Traffic
   set dscp ef
    priority
    police cir 512000 bc 640
 class OracleTraffic
    shape average 1536000
   set dscp af31
 class class-default
    queue-limit 3000
    shape average 2048000

class-map match-all OracleTraffic
  match access-group 103

class-map match-any Voice-Sig
  match  dscp af31
  match  dscp cs3

class-map match-any Voice-Traffic
  match access-group 100
  match  dscp ef
  match  dscp af41