Hi there,

I am learning the basics of QoS on the 3560 platform. To begin I applied the "auto qos voip trust" command on two interfaces. This command enabled some basic mls qos statements in the config.

The specific interface looked like this:

interface GigabitEthernet0/20

srr-queue bandwidth share 10 10 60 20

srr-queue bandwidth shape 10 0 0 0

queue-set 2

mls qos trust cos

auto qos voip trust

end

Then, I wanted to understand the SRR shaping command. So what i did was, configure two interfaces, with two hosts, and removed the SRR share commands. The two interfaces, with the two hosts (same VLAN), now look like this:

interface GigabitEthernet0/1

duplex full

speed 100

queue-set 2

mls qos trust cos

auto qos voip trust

spanning-tree portfast

end

!

interface GigabitEthernet0/2

duplex full

speed 100

srr-queue bandwidth shape 10 100 220 120

queue-set 2

mls qos trust cos

auto qos voip trust

spanning-tree portfast

end

With this config i did some bandwidth tests, by copying a big file between G0/1 and G0/2. Copying a file from G0/1 to G0/2 resulted in a speed of 0.83mbit

Copying a file from G0/2 to G0/1 resulted in a full speed bandwidth of 100mbit.

This behavior is exactly the opposite of what i expected to get with this config. Apparently the "srr-queue bandwidth shape" statement on G0/2 did reduce the inbound traffic (download). From what I've learned from the docs, SRR shaping applies to the egress queues, also called outbound, so from port G0/2 to G0/1 and not vice versa?

Any hints will be appreciated..