2960 QoS policy

[warendondon]

Hi,

We have to configure QoS on 2960 LAN Base switch for Voice, considering https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/12-2_53_se/configuration/guide/2960scg/swqos.html#20651

We set DSCP from Voice devices, and trust dscp on ports. Howerver, we cannot find what is the default policy for bandwith. Does it mean that with "only" mls qos activation and trust dscp on port, traffic is not priorized ?

Thanks for help,

Regards,

[Reza Sharifi]

Hi,

We set DSCP from Voice devices, and trust dscp on ports. Howerver, we cannot find what is the default policy for bandwith. Does it mean that with "only" mls qos activation and trust dscp on port, traffic is not priorized ?

With DSCP, the traffic is prioritized for voice traffic (CoS=5) and data traffic gets low priority, which is default (CoS=0).

HTH

[warendondon]

Hi,

Thanks for reply. But after configuring DSCP, we should see somewhere what policy is applied to priorize packets ?

Where could we see such configuration ? Doc speaks about policies or policer, but none is configured. Is there any defaut config about this ?

Regards,

[Reza Sharifi · Accepted solution]

Hi,

we should see somewhere what policy is applied to priorize packets ?

Configuring policy is optional. You configure policy for shaping, queening, marking, etc... but that is not always needed.

If you want a simple qos config for VoIP phones, you can configure Auto-QOS or manually configure qos for access ports and trunk ports. After qos is configures, you should be able to see the marking using wireshark.

HTH

[Joseph W. Doherty]

"We set DSCP from Voice devices, and trust dscp on ports. Howerver, we cannot find what is the default policy for bandwith. Does it mean that with "only" mls qos activation and trust dscp on port, traffic is not priorized ?"

Yes, the default QoS configuration does NOT prioritize any traffic (in your reference, see table 34-9). What it does it activate four egress queues, each given a equal minimum 25% bandwidth guarantee, and the DSCPs are split into/across the four egress queues. For default DSCP to egress mapping, see table 34-11.

If you add the interface command, "priority-queue out", the first egress queue will be serviced before the other three. Normally you would direct VoIP bearer traffic to this queue (if marked DSCP EF, the defaults listed in table 34-11 should accomplish this).