Discussion on:

Limit bandwidth on a Cisco Catalyst switch port

Both use wrr-queues not srr-queues.

You say, "However, you probably won't get the same level of performance from the 10-Mb Ethernet port." Is this because if you hard code the port speed to 10-Mb, duplex is disabled?

quite helpful!

thanks.

Can this be done to say limit the badnwidth used by local lan users and limit their badnwidth utilization for surfing the net?

Thanks,
razorack--

You state the following:

"Switch(config-if)# srr-queue bandwidth limit 90
The 90 sets the outbound bandwidth limit on the port to 90 percent of the port speed. Since this is a 100-Mb port, this should limit the outbound traffic from the port to 10 Mb."

Actually, according to the Cisco command reference, this would result in a traffic limit of 90Mbps, not 10Mbps. Good reminder of a useful command, however. Thanks.

Yep, your right, I checked the cisco documentation as below:-

Usage Guidelines
If you configure this command to 80 percent, the port is idle 20 percent of the time. The line rate drops to 80 percent of the connected speed. These values are not exact because the hardware adjusts the line rate in increments of six.

This example shows how to limit a port to 800 Mb/s:

Switch(config)# interface gigabitethernet0/1

Switch(config-if)# srr-queue bandwidth limit 80

I don't seem to have this command. I am running version 12.2(25) but I don't see the wrr-queue or srr-queue.

This is a great command to have. Thanks for the info.

Can this be applied to a switch-mod that is on-board a 2800 rtr (NM-16ESW)..?

I disagree with this statement:

The 90 sets the outbound bandwidth limit on the port to 90 percent of the port speed. Since this is a 100-Mb port, this should limit the outbound traffic from the port to 10 Mb

90 percent of the port speed (100MB) is not 10MB but 90MB.

Anyone know if this is a capability using CATOS?

I've always wanted to know how admins configure this. Turning up a clients bandwidth or connections speed is extremely useful. However, I have an inquiry. It's obvious that there are instant benefits from have increased speed; however, what are the down sides? Would there be instances where turning it down would be a better option(for instance a hardware problem or reduction in noise on the line type stuff?)? Thanks for posting.

Would it not be limit 10, since you want 10 megs on a 100 meg port?

In the example above it states that the 90 sets the outbound bandwidth limit on the port to 90 percent of the port speed. Therefore wouldn't the client bandwidth be 90 meg?

Based on the link David Davis refers to, http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/software/release/12.2_37_se/command/reference/cli3.html#wp1947391, and the example he proposes, "srr-queue bandwidth limit 90", would give an outbound of 90Mb. The correct syntax would be "srr-queue bandwidth limit 10" (without quotes) in order to get an outbound of 10Mb.

this was exactly what I was looking for. Now, you mentioned that if I wanted to limit the speed to something less than 10Mb, the I would have to adjust the physical port speed ...

why couldn't I just say: srr-queue bandwidth limit 2
for a 2MB connection?

Because by default the minimum is 10%

this command is not work in my cisco router (2950)
please reply me why its not work my mail id is mohammedismailahmed@yahoo.com please mail me Sir

I think the discussion is focused on outbound traffic. How do I limit the download / inbound bandwidth for my Cisco 3550?

Does it really do the limitation coz i did the same in my cisco 2960 but it didnt seem to work or how am i suppose to see is its working or not .... coz after the comment the bandwidth seems same to me

According to the Cisco command reference (and according to my results), setting the srr-queue bandwidth limit to 90 limits throughput TO 90% - not BY 90%. "srr-queue bandwidth limit 90" sets interface idle time to 10%, while permitting traffic 90% of the time, so the result is an effective 90 Mbps on a 100 Mbps port. Note that although this command accepts any value between 10 and 90 inclusive, the interface idle time is adjusted only in increments of 6. Rather than rounding to the nearest multiple of 6, it appears to truncate. So, "srr-queue bandwidth limit 10" actually results in 6% throughput, but "srr-queue bandwidth limit 12" results in 12% throughput.

Sir i want to limit the bandwith in kilobits how can i configure on fast ethernet port.... By bandwith command what happens is the speed doesnt changes.....please help us as we have to give lease line in kilobits and 2Mb ,4Mb,and in multiples of 2