Any implication using ACL to classify ALL traffic?

[Anonymous]

Been given a requirement to implement a QoS configuration that I will be prioritising Voice and Video via an ACL on certain ports numbers.

My query is that I would then use a permit all on all remaining traffic to mark it with CS1 (DSCP  and then put this into QP2.

The idea I believe is that anything quantified as 'bad' traffic can then be put into best effort, QP1, if required.

So my question is, all though I know ACL's are done in hardware I'm not sure if using an ACL for this purpose on every single packet would over burden the switch in some manner?

The switch is an X440, but interested if the outcome should this be a G2 or any other model be the same?

Many thanks in advance.

[Erik_Auerswald]

It might work better to change the default dot1p and DSCP QP to QP2, and use ACLs to classify only special traffic (higher or lower priority than standard).
configure dot1p type dot1p_priority {qosprofile} qosprofile
configure diffserv examination code-point code_point {qosprofile} qosprofileYou can find additional ideas and information in RFC 4594.

[Erik_Auerswald]

As a start, you could match on the dot1p tag and dscp (or ip-tos) and change only frames with a value of 0 in both to QP2. That should leave anything already marked in the respective traffic class, and anything non-marked or non-IP in QP1. That of course assumes that network control is correctly marked and no traffic is incorrectly marked for a QoS class it is not supposed to use. You might need to add ARP to QP2 as well.

[Erik_Auerswald]

Hi Martin,

packet editing via ACL should be implemented in hardware and not affect forwarding performance. ACLs are applied to every single packet anyway. As long as the switch has sufficient resources to apply the ACL you should be fine.

Erik

[Erik_Auerswald]

As an aside, you should ensure that you do not downgrade QoS of network control traffic.