QoS - DSCP Tagging

[chrislisser]

I'm configuring QoS to priortize our voice traffic. This is the first time I've set up QoS so I'm a little confused.

I have identified my VoIP traffic class and am tagging the packets coming into the Ethernet port with DSCP ef. My question is: Will the tagged packets be automatically priortized or do I also have to add something like this:

access-list 100 permit ip any any dscp ef

class-map VoIP

match access-group 100

policy-map QoS-VoIP

class VoIP

priority 128

class class-default

fair-queue

interface s0

service-policy output QoS-VoIP

[lgijssel]

You do need to configure the QoS on the router as well. If you don't, the router will use it's queuing mechanism to forward the traffic and this is likely not giving the desired priority to your voice traffic.

What you propose looks more or less ok to start with.

Regards,

Leo

[tdrais]

Yes you must apply a outbound service policy to get the QoS to work properly. Although the serial line runs fair-queue by default that is not good enough to run voice.

You can use MATCH DSCP rathen than a access list if you want to.