rate-limit on GSR router

[massipace]

Hi,

I want to limit input and output rate to a gigabitethernet interface at 200Mb/s.

So, following the rule:

bc=(rate/8)*1,5 secs

be=2*bc

the command look like this

rate-limit input access-group <ACL> 200000000 37500000 75000000 conform-action transmit exceeded-action drop

rate-limit output access-group <ACL> 200000000 37500000 75000000 conform-action transmit exceeded-action drop

but when I configure this command on GSR it shows the following messages:

"Adjusting normal burst to match hardware limit of 16777215 bytes"

"Adjusting exceed burst to match hardware limit of 16777215 bytes"

the bc and be value in final configuration are automatically set to 16777215 lower than the correct value from the formula.

Does the value imposed by the GSR limit the traffic lower than 200 Mbit/s?

Wath can I do to set bc and be value according with the formula?

Thanks

Massimiliano

[jackyoung]

I think it is the limitation of the line card or the GSR. However, did you try to use the generic traffic shaping ? It should work w/ Ethernet but don't know will it work w/ GSR.

[massipace]

I tried but GTS is not supported on GSR...

Are there more options to configure a rate-limit?

[jackyoung]

Sorry, I have no idea and need Cisco to explain the limitation of the BE BC.... Or the final solution to add an external box to limit the bandwidth, but it is not preferred.

However, did you test the throughput when the box modify the parameter itself ?

[massipace]

do you mean using default values?

the command need to input manually the burst value

only remain to check the configuration with a smartbit.

[jackyoung]

What I mean due to there may be limitation on the BE, BC, so can try to test the throughtput w/ current setting. Or add external box to make it work. I did not try to rate-limit as high as 200M, so I cannot prove it by my experience.

[wochanda]

It sounds like you're using an E3 linecard, which does all policing in hardware. Since this is the case, there are limited values the ASIC supports for CIR/BC/BE. The limit you're running into is the BC/BE cannot go higher than 16777215 bytes.

Although you're hitting this limitation, it shouldn't affect the average rate going through the interface, unless the traffic you're pushing is VERY bursty.

Read here to see how the dual leaky-bucket algorithm works, and how BC and BE relate to each other:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_reference_chapter09186a0080087f42.html#wp1064737