2950 MLS QoS

[John Blakley]

All,

I was under the impression that a port needed to be trunked in order to have cos marked in the frame. I have the following:

Host --> 2950 --> router

On the router I have:

class-map any

match dscp cs3

match dscp default

match ip precedence 3

policy-map any

class any

int fa0/0

service-policy input any

On the 2950, port fa0/1 (router) and port fa03 (pc) is connected I have:

int fa0/1

switchport mode access

mls qos trust

int fa0/3

switchport mode access

mls qos cos 3

mls qos cos override

I can see hits on cs3 on the router which tells me that the packet is being marked regardless of the port being trunked. Am I missing something?

Thanks,

John

[Reza Sharifi]

John,

It should work fine with an access port as uplink.  You are just using the native vlan or untag frames.

HTH

[John Blakley]

Reza,

I get it now. CS3 is my DSCP marking that's being translated. I wasn't matching on cos 3, but instead was translating from cos3 to dscp cs3 and that was why I was seeing hits.

Thanks!

John

[Joseph W. Doherty]

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Posting

Right.  CoS is only available in VLAN tagged frames.  IP ToS is part of all IP packets.

PS:

BTW, you don't really need to match on both CS3 and IP Prec 3; the latter will also match the former.  (The converse is not true.)