09-29-2008 08:57 AM - edited 03-06-2019 01:39 AM
Hello all,
I am trying to do a test of some thin clients internally at my office and I want to emulate T1 bandwidth on a switchport so I can get an idea of how they will perform at the other end of a T1 link.
I have been using a policy-map to achieve the bandwidth policing, but I am not sure it is working. Here is what I have done: (G0/2 is the downlink port to the switch the thin clients are connected to.)
policy-map Test_Limit
class class-default
police 1544000 193000 exceed-action drop
interface GigabitEthernet0/2
description Trunk to test switch
switchport mode trunk
service-policy output Test_Limit
I used one of those bandwidth testers on the Internet and got the 9.3Mb/s result both before and after I applied the policy.
Am I doing this correctly, or is there a better way?
For reference, the switch I am applying the policy on is a C3560-24PS running 12.2(25)SEE and the test switch with the thin clients is a C2960-24TT-L running 12.2(35)SE5.
Thanks,
Chris
09-29-2008 09:12 AM
Hello Chris,
if you want to emulate T1 bandwidth you need to do it in both directions
use a second policy-map for inbound direction
make it similar to the first and apply it inbound
policy-map Test_Limit_IN
class class-default
police 1544000 193000 exceed-action drop
int gi0/2
service-policy output Test_Limit
service-policy input Test_Limit_IN
to verify if the commands are effective use
sh policy-map
if no matches they are bypassed by multilayer switching
there is a limitation on this platform:
Follow these guidelines when configuring policy maps on physical ports:
â¢You can attach only one policy map per ingress port.
see
This would explain your results with and without the policer
if I understand correctly the policer is supported only inbound on a physical interface
Hope to help
Giuseppe
09-29-2008 09:14 AM
". . . or is there a better way?"
The problem with policers, they don't emulate a slower interface which usually also queues overspeed traffic. A shaper would be a better choice for T1 emulation, but don't believe the 3560 supports it. However, the "srr-queue bandwidth limit" command should mimic the queuing better but it might not emulate the speed exactly. For best speed match, set port to 10 Mbps then set "srr-queue bandwidth limit" to 15(%).
09-29-2008 09:27 AM
Thanks for the replies, guys. I think I will try the srr-queue bandwidth limit command. Unfortunately I already tried applying and input and output policy, but the switch would not allow me to apply a policy in the input direction.
Thanks!
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