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bandwidth, cir and mincir in FR?

sleepingandrew
Level 1
Level 1

What is the difference among the three in frame-relay configuration? How to properly configure the three? And what are the default values if they are not manually configured? Thanks.

2 Replies 2

bbranch
Level 3
Level 3

CIR

The average rate you want to send traffic out on a given PVC in bps. This is generally higher than the guaranteed rate but less than the access rate (bandwidth)

Default CIR = 56K

Calculated as Tc = Bc / CIR

Tc = Time, Bc = Committed Burst

MinCIR

The actual guaranteed rate obtained from service provider in bps. This value should be the minimum rate you should drop to in the event of congestion (dropping below this rate implies you are not getting the bandwidth you are paying for).

Default MinCIR = 1/2 CIR

There are some good paper on FR Traffic Shaping on CCO at:

http://www.cisco.com/en/US/tech/tk713/tk237/technologies_configuration_example09186a00800942f8.shtml

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_configuration_guide_chapter09186a00800c60d3.html

http://www.cisco.com/en/US/tech/tk713/tk237/technologies_tech_note09186a0080094372.shtml

Thanks for the links.

Say if I have a FR with 128K CIR and 64 EIR given by the telco, then what values of "cir" and "mincir" should I use? What would be the effect if i leave them as default? Is it really important to set these values correctly?

Thanks

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