09-19-2008 06:31 AM - edited 03-15-2019 01:24 PM
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..
09-19-2008 11:14 AM
Your concern makes sense to me, afaik SRR bandwidth shape is for egress queues.
Can we see the following:
show mls qos
show mls qos interface (interface #)
show mls qos interface [interface #] queueing
and the sh run and sh ver.
Which COS value the file is set to? 0, 3 ?
If you remove mls qos trust cos or add mls qos trust dscp? same behaviour?
Thanks
09-21-2008 11:18 PM
gogasca, thanks for your reply.
I don't do anything with the CoS/DSCP value, so it hits Q4, 1/120 of the total bandwidth.
I've included a txt with all of the requested show commands.
09-21-2008 11:27 PM
09-23-2008 09:07 PM
Well, SRR is set up in the inverse proportion. So you have set up "10" for the first queue, which means 1/10, or 10%. 10% of 1 gigabit is 100 Mbps...
So, isn't everything working correctly?
Also, did you check your settings with show mls qos commands? Do you have mls qos enabled globaly?
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