I can see why you would be confused because by default queue 1 is not acting as
the priority queue, and needs to be enabled manually with the "priority-queue
out" command
Just to verify
Cat1(config)#do show mls qos int gig0/1 que
GigabitEthernet0/1
Egress Priority Queue : disabled
Shaped queue weights (absolute) : 25 0 0 0
Shared queue weights : 25 25 25 25
The port bandwidth limit : 100 (Operational Bandwidth:100.0)
The port is mapped to qset : 1
Now let's enable to priority queue
Cat1(config-if)#int gig0/1
Cat1(config-if)#priority-queue out
This time it should show as "enabled"
Cat1(config-if)#do show mls qos int gig0/1 que
GigabitEthernet0/1
Egress Priority Queue : enabled
Shaped queue weights (absolute) : 25 0 0 0
Shared queue weights : 25 25 25 25
The port bandwidth limit : 100 (Operational Bandwidth:100.0)
The port is mapped to qset : 1
Here is a blog on 3560 QoS that may help as well
http://blog.ipexpert.com/2010/05/26/introduction-to-catalyst-3560-qos/
Steve Di Bias
________________________________
From: [email protected]
[mailto:[email protected]] On Behalf Of Ryan Jensen
Sent: Wednesday, October 20, 2010 1:22 PM
To: [email protected]
Subject: Re: [OSL | CCIE_RS] 3560 Queueing and srr-queue bandwidth
I found my answer in Cisco's documentation.
http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_50_se/configuration/guide/swqos.html#wp1284809
All four queues participate in the SRR unless the expedite queue is enabled, in
which case the first bandwidth weight is ignored and is not used in the ratio
calculation. The expedite queue is a priority queue, and it is serviced until
empty before the other queues are serviced. You enable the expedite queue by
using the priority-queue out interface configuration command.
On Wed, Oct 20, 2010 at 3:12 PM, Ryan Jensen
<[email protected]<mailto:[email protected]>> wrote:
Hi all,
I have some confusion when it comes to egress queueing on the 3560.
Reading through the study guide, the command format is: srr-queue bandwidth
{share|shape} weight1 weight2 weight3 weight4
I understand that the weightX values are relative, but i have some confusion.
My reading (CCIE Routing and switching Exam Certification Guide 4th Ed) says
"When you configure the priority queue, the switch ignores any bandwidth values
assigned to the priority queue in the share or shape commands." And leaves it
at that. Could I theoretically configure somthing that has weight 0 for Queue
1? Like: srr-queue bandwidth shape 0 20 40 20 under an interface? How does the
switch know how much weight to assign to the PQ on egress? Is this determined
by the queue-set configuration? (mls qos queue-set output 1 buffers 40 20 30
10).What happens if I don't assign a queue-set to an interface? Unfortunately I
don't have any 3560s available to test this with. Can anyone help? Thanks in
advance.
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