QOS over portchannel interface ?

[dclee]

I have a 6509 and 6513 trunked together in the lab currently via a port channel (po2) 4 ethernet ports and LACP.

All seems to be working as advertised.

The 6509 is handling all of the L3 traffic and the 6513 is only L2.

I have a CIC server (VOIP) sitting on a vlan on the 6509 and would like to test a workstation that is in another vlan that is connected on the 6513.

Connectivity works and qos is enabled on all points except the interconnect between the 2 switches which is po2.

Do I turn on QOS on the port channel as well as the four ethernet ports that makeup the port channel ?

Do I even need QOS on this interface if QOS is enabled everywhere else in the path ?

Any help would be appreciated.

Cheers

Dave

[lgijssel]

When implementing qos, it is best practice to do it everywhere.

Perhaps this channel will never become congested, in which case the effects of running qos are marginal.

However, between switches you should always establish a trust. Either trust cos or dscp.

If this is omitted, chances are that existing qos marking are overwritten to cs0.

As you may understand, this will nullify qos operation in the remainder of the path to the destination.

When such a misconfiguration is done before traffic hits a WAN link, you will experience severe degradation of (especially) voice quality.

regards,

Leo

[dclee]

Hey leo, do I need to configure the QOS on the port channel int as well as the physcial interfaces of the portchannel ?

Or just the port channel ?

Cheers

Dave

[lgijssel]

Having an issue with it?

That would not be surprising because qos with etherchannels is less straightforward than one would think.

A lot of my engineers have problems with that as well. The exact config depends on the type of hardware.

Please try to configure auto-qos on the physical ports and put the trust on the channel.

regards,

Leo

[dclee]

I'll do that...I can def autoqos the ports and MLS QOS trust dscp the port channel.

I'll runup a sniffer to ensure the markings make it all the way thru.

Thanks

Dave