From: wim.depauw@getronics.com
Date: Fri Dec 28 2007 - 10:08:33 ART
Hi,
We're testing policing and shaping on 3750 ME switch so our customers BW is limited to the bw he orders.
I did some testing with the above options and came to the following :
test setup:
PC------------------SW( fa0/1)
On my PC I have a FTP/TFTP server running and I downloaded a file of 500KByte to flash and back
1) Command : SRR-queue bandwidth shape 56000
- Advantage :Doesn't loose any packets UDP/TCP but just delays it ,
- Disadvantage : You can only configure it on a egress queue so when you upload a file to the PC your bw gets a lot higher then configured .This is because you only send ACK back to the SW which are very small in size.
2) Command : service-police input test
policy-map test
class class-default
police 56000 8000 exceed-action drop
-disadvantage : Only configured on input direction , output is not supported
UDP traffic is dropped so a lot of retries are sended which leads to the not required perfomance ( instead of 56 Kb/s I had 1 Kb/s for UDP traffic )
-Advantage : For TCP traffic I got around 40 Kb/sec without any drops.I think for a bigger file it will give me my required speed.
3)Command Storm-control unicast level 56000
Advantage : It limits as well my UDP/TCP traffic with minimal drops
Disadvantage: Speed goes very irregular( fast then slow ) , also I noticed when I upload to the PC my limitation is not working as it supposed to be.
I tried it with a bigger file of 5 MB and I got a upload speed of 2,4Mb/s.
Most likely storm-control is also working only on the inbound direction of your switch.
So there are 3 methods to limit your traffic and they all got their disadvantages and to be honest they don't give us the results we want.
Do you know any other possibilities ?
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