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2950 MLS QoS

John Blakley
VIP Alumni
VIP Alumni

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

HTH, John *** Please rate all useful posts ***
3 Replies 3

Reza Sharifi
Hall of Fame
Hall of Fame

John,

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

HTH

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

HTH, John *** Please rate all useful posts ***

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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.)