Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

3750 QoS - egress interface

Please guide me to understand the 3750 QoS mechanism.

Q1) DOC say "priority-queue out" is ignore shape and share command. is it meaning always give priority to cos=5(or dscp=ef) traffic regardless the shape command?

Q2) I want to give 10% guaranteed bandwidth to voice traffic. what's best command in the 3750 egress interface? shape only or combine with priority-queue?

Q3) Any doc explained the output for the command "show mls qos interface f1/0/1 statistics"? the meaning of the each field.

Thanks in advance,

6 REPLIES
Purple

Re: 3750 QoS - egress interface

Hi,

1. That is correct. The expedite queue is a priority queue, and it is serviced until empty before the other queues are serviced. This has the potential to hog all the bandwidth on an interface....

2. I would use the priorty-queue command as it will give the best jitter and latency characteristics for your voice traffic. If you want to limit this bandwidth, you should do it via policing on ingress interfaces.

3. Check out this link:

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_command_reference_chapter09186a00805023be.html#wp1947019

Hope that helps - pls rate the post if it does.

Regards,

Paresh

New Member

Re: 3750 QoS - egress interface

Thank you for the good information.

The URL only explained the each field but I need the information the column which has five per row.

Another question is why always dscp=0 traffic is encountered much more versus dscp=ef in the following scenario.

- two traffic generators connect to the 3750 switch interface and marked dscp=0 and dscp=ef each

- I can only see the related traffic(dscp=0 or ef) if I run only one traffic generator each by the "show mls qos interface f1/0/1 statistics"

- when I run together the two generator and forwarding together into the egress interface, always dscp=0 traffic is much more than dscp=ef. service-policy command only in the ingress interface to mark the dscp and no qos in the egress interface.

Thanks,

Purple

Re: 3750 QoS - egress interface

Hi,

When looking at the output of the command, you see five columns of statistics per line. Now note that each row starts with a range of numbers. For example, the line starting 10-14 means that the five values in the same row correspond to counts for DSCP 10, 11, 12, 13 and 14.

Could you post the configs of the relevant interfaces that you are using ?

Hope that helps - pls rate the post if it does.

Regards,

Paresh

Purple

Re: 3750 QoS - egress interface

Just another question: when you are using both the traffic generators, how much traffic are you submitting ? Is the sum of both greater than the bandwidth of the egress interface ?

Paresh

New Member

Re: 3750 QoS - egress interface

the two ingress and one egress interfaces are all FastEthernet and generates 50Mbps each via Solawinds "WAN Killer". follows the configuration.

!

access-l 131 perm ip host 172.16.131.100 host 10.10.10.10

access-l 132 perm ip host 172.16.132.100 host 10.10.10.10

!

class-map class-131

match access-group 131

!

class-map class-132

match access-group 132

!

policy-map policy-130

class class-131

set dscp default

class class-132

set dscp ef

!

interface f1/0/47 <-- generator#1

service-policy input policy-130

!

interface f1/0/48 <-- generator#2

service-policy input policy-130

!

interface f1/0/1 <-- egress interface.

Thanks,

Purple

Re: 3750 QoS - egress interface

Hi,

Hi,

Could you first clear the couners, run your test again and then get the output of the following:

show mls qos interface f1/0/47 statistics

show mls qos interface f1/0/48 statistics

show mls qos interface f1/0/1 statistics

Thanks,

Paresh

337
Views
5
Helpful
6
Replies