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Webcast-Catalyst9k
New Member

10720 shaping onto ethernet - CIR value includes all L2 ?

The documentation on 10720 (MQC) shaping says "..CIR is measured in bits of IP packets per second, and includes the IP header and link-specific headers". It only mentions 'headers', not 'trailers'. Does this mean the 4Byte CRC trailer is not included in the CIR figure ? What about .1q headers - are they included already or is special allowance needed ?

Is there anything (else) non-standard about the way 10720 shapes onto gige/fe ?

2 REPLIES
Bronze

Re: 10720 shaping onto ethernet - CIR value includes all L2 ?

The CIR is measured in bytes of IP packets per second, i.e., it includes the IP header, but not link specific headers.

http://www.faqs.org/rfcs/rfc2697.html

New Member

Re: 10720 shaping onto ethernet - CIR value includes all L2 ?

Thanks for the reply.

This turns out to be a classic case of "don't trust the documentation".

In http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/prod_configuration_guide09186a008009d848.html

it says

"CIR is measured in bits of IP packets per second, and includes the IP header and link-specific headers."

then, a few paragraphs further on, it says

"CIR is measured in bits of IP packets per second, and includes the IP header but not link-specific headers."

So take your pick !

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