6500 QOS policing question

[Jon Marshall]

I am very rusty on QOS in general and 6500 QOS in particular so would appreciate it if someone could give a definitive answer on the following. 

Pair of 6500s running 12.2(33)SXI with multiple SVIs, using vlan based QOS and applying service policies for policing traffic both inbound and outbound on the SVIs. 

My question is, if we use the same policy map name across mutiple SVIs does the 6500 still police on a per vlan basis or does it aggregate the traffic for all the SVIs using the same policy map name eg. 

a policy map called "50mbps" which policies traffic to 50mbps. 

If the same policy map is applied to 5 SVIs does this mean each vlan gets 50Mbps or does it mean that the 50Mbps is split between 5 vlans ? 

Jon

[Joseph W. Doherty]

Jon, that IOS is for a sup720, correct?

it should be per VLAN interface, if that's where the policy, with policer, is applied. (I'm also assuming all VLAN interfaces have a "mls qos vlan-based" applied on them too.)

[Jon Marshall]

Hi Joe

Yes it's a sup720 and as you say the "mls qos vlan-based" is configured on physical ports and policer is applied to SVI. 

Obviously when I do a "sh mls qos" and see policed packets for that policy I have no way of knowing which vlan(s) the traffic has been policed for, bit like using same acl for multiple SVIs and looking at hit counters, which is fine as long as I can be sure each vlan is getting 50mbps dedicated (as per previous example). 

I was just wondering that because the statistics will be shared across all vlans using the same policy map in terms of show commands etc. whether that would affect the actual bandwidth allocated to each vlan if you see what I mean. 

Jon

[Joseph W. Doherty]

Yea, something like a shared ACL will accumulate stats for however it's used, but policy stats should be per interface instance.