Adding QoS Commands to a Cisco 2940 8 Port Switch

[switchUpswitchDown]

Hi,

I've got an 8 port Cisco 2940-8TF-S switch, which I'm trying to add QoS VLAN settings to one particular port.

The lines of config I'm trying to add are below:

srr-queue bandwidth share 10 10 60 20
srr-queue bandwidth shape 10 0 0 0
priority-queue out
mls qos trust cos
auto qos voip trust
spanning-tree portfast
spanning-tree bpduguard enable

I've entered the 'config t > int fa0/1' command but can't quite figure out what the commands would be for qos entry.

Can anyone lend a helping hand?

Thanks!

[Giuseppe Larosa]

Hello wildcard,

a good starting point can be the following thread that refers to your device

https://community.cisco.com/t5/switching/quality-of-service-on-cisco-2940/td-p/2682393?dtid=osscdc000283

Inside the thread you can find a link to the command reference.

Generally speaking, you need to enable mls qos on global configuration before adding QoS commands under a specific interface.

Edit:

the link to command reference is not working anymore.

Edit2:

Of the commands that you have proposed I would use only the first four

srr-queue bandwidth share 10 10 60 20
srr-queue bandwidth shape 10 0 0 0
priority-queue out
mls qos trust cos

The last two commands refer to spanning-tree and does not support to connect an unwanted switch to the port.

They are not related to QoS but they are recommended to protect STP (bdpu guard) and to make the port fast in coming up (portfast by skipping transitory states it is safe only if the port connects to a end user device like a PC)

Hope to help

Giuseppe

[switchUpswitchDown]

Thanks for your reply Giuseppe.

Do you know the command needed to enable MLS QOS on this model of switch?

Thanks!

[paul driver]

Hello

Why do you need to apply qos just to one specific interface what is it for?

[Giuseppe Larosa]

Hello ,

I would expect to be

mls qos

on global config

WARNING: enabling this command will cause the switch to rewrite DSCP value on all ports to 0 this should be the default.

So think about it and make a careful action plan.

You may need to add

mls qos trust DSCP

on all access ports where important traffic is received.

Hope to help

Giuseppe