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CAR explanation

Hi!

I´ve got an implentation that uses CAR (committed access rate) in order to prioritize traffic. The CAR wants to split 32K of bandwidth between two kinds of traffic. However, since I am not familiar with CAR ( and of course I didnt design the solution) I am not sure how can I change or vary the CAR values (rate-limit command). I want to know what does the 1st, 2nd, 3rd value mean. I read some documentation related to CAR but the explanation was done based on some bucket and tokes theory. I want to have a simple explanation about CAR since my customer wants to vary those CAR values to assign more bandwith to one of the two traffic and I havent been able to explain him how can he do that changing the rate limit values. I am pasting the way I am doing the CAR.

Thanks,

Mario

rate-limit input access-group 120 16000 16000 24000 conform-action transmit exceed-action transmit

rate-limit input access-group 121 16000 16000 24000 conform-action transmit exceed-action drop

access-list 120 permit icmp 10.150.192.0 0.0.63.255 host 133.1.0.20

access-list 120 permit tcp 10.150.192.0 0.0.63.255 host 133.1.0.20

access-list 120 permit ip any host 10.1.128.30

access-list 120 permit ip any host 172.24.2.4

access-list 120 permit ip any host 128.1.100.4

access-list 120 permit ip any host 10.1.128.11

access-list 120 permit ip any host 10.1.128.10

access-list 120 permit ip any host 10.1.1.102

access-list 121 deny icmp 10.150.192.0 0.0.63.255 host 133.1.0.20

access-list 121 deny tcp 10.150.192.0 0.0.63.255 host 133.1.0.20

access-list 121 deny ip any host 10.1.128.30

access-list 121 deny ip any host 172.24.2.4

access-list 121 deny ip any host 128.1.100.4

access-list 121 deny ip any host 10.1.128.11

access-list 121 deny ip any host 10.1.128.10

access-list 121 deny ip any host 10.1.1.102

access-list 121 permit ip any any

1 REPLY
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Re: CAR explanation

The first value is the average rate that you can transmit traffic, the above would be 16K average , the second value is the normal burst size this is the amount of traffic you will be allowed to send prior to exceeding the rate limit , in the above in addition to the 16K you are allowed to send traffic at normally , you can send an additional 16K during any 1 time period. the third value is the extended burst , this is the amount of traffic you can send in addtion to the normal burst you can send during one time period. After these values are exhausted the traffic is dropped in the case of ACL 121 in regards to ACL 120 the traffic is still transmitted but may be dropped by the provider.

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