mls qos queueing-only

[Marco1234]

Hello,

I have a question about the command mls qos queueing-only command on a c6513-E. I see in the global parameters that it trust cos on all ports. I tag all my traffic with DSCP on all of our VOIP devices. If I use that command, does it still map the DSCP value to the right COS value to get in the right queue ? (priority queue). If not, how should I configure it ? I'm not interested in policing or tagging the traffic at the switch level since it's already tagged. I have used also the no mls qos rewrite command also.

Thanks for your help !

Marco.

[Joseph W. Doherty]

Generally on the "older" Cisco L2 devices, if QoS is enabled, you need to trust ingress markings otherwise they will be reset.

Also if possible, avoid working with L2 CoS, instead work with L3 ToS.

Many Cisco device QoS defaults give different treatment based on QoS markings.  With the 6500 series, QoS capabilities vary with line cards.  As you didn't note supervisor, IOS version or line cards, unable to note whether PQ is even an available feature.

[Marco1234]

Hello Joseph,

Here are more info:

ROM: System Bootstrap, Version 12.2(17r)SX5, RELEASE SOFTWARE (fc1)

Mod Ports Card Type Model Serial No.
--- ----- -------------------------------------- ------------------ -----------
1 48 48-port 10/100/1000 RJ45 EtherModule WS-X6148A-GE-TX SAD091104ZT
2 48 48-port 10/100/1000 RJ45 EtherModule WS-X6148A-GE-TX SAD0945031K
3 48 48-port 10/100/1000 RJ45 EtherModule WS-X6148A-GE-45AF SAL09465BDP
4 48 48-port 10/100/1000 RJ45 EtherModule WS-X6148A-GE-45AF SAL1015JL3T
5 48 48-port 10/100/1000 RJ45 EtherModule WS-X6148A-GE-45AF SAL1303GPNN
6 48 48-port 10/100/1000 RJ45 EtherModule WS-X6148A-GE-45AF SAD09470407
7 2 Supervisor Engine 720 (Hot) WS-SUP720-BASE SAL1006CSUR
8 2 Supervisor Engine 720 (Active) WS-SUP720-BASE SAD0817071T
9 16 SFM-capable 16 port 1000mb GBIC WS-X6516A-GBIC SAL08186X00

Mod Sub-Module Model Serial Hw Status
---- --------------------------- ------------------ ----------- ------- -------
3 IEEE Voice Daughter Card WS-F6K-48-AF SAL09465029 2.0 Ok
4 IEEE Voice Daughter Card WS-F6K-48-AF SAL1015JUU5 2.0 Ok
5 IEEE Voice Daughter Card WS-F6K-48-AF SAL1302FZL8 2.3 Ok
6 IEEE Voice Daughter Card WS-F6K-GE48-AF SAD0947029K 1.2 Ok
7 Policy Feature Card 3 WS-F6K-PFC3A SAL1006CRU3 2.5 Ok
7 MSFC3 Daughterboard WS-SUP720 SAL1006CUFT 2.6 Ok
8 Policy Feature Card 3 WS-F6K-PFC3A SAD081709M1 2.3 Ok
8 MSFC3 Daughterboard WS-SUP720 SAD081705N3 2.2 Ok
9 Distributed Forwarding Card WS-F6K-DFC3A SAL0825AG37 2.2 Ok

If i turn on the queueing-only option and I try to trust dscp, it gives me a warning saying that even though I change the trust, the COS is still the trust in application. Does that mean it doesn't take in account my ingress dscp marks ?

Thanks.