In frame relay traffic shaping;
- is CIR the committed BW from the service provider.
I am contemplating of applying for an FR service but I do not what to ask. I need to connect 2 sites. Maybe I can start off with a 64Kbps between the 2. Would that mean I should apply for a 64 Kbps CIR? What about the Be and Bc?
Any help will be appreciated.
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typically, a Frame Relay provider would guarantee half of the CIR. So, if you ask for a 64K circuit, 32K would be guaranteed, the rest of the traffic would be marked as ‘discard eligibible, or DE’, which means that in case of congestion, the traffic would be dropped.
Regarding the Be and Bc values: the Bc value is related to the configured CIR. If you want to apply FR Traffic Shaping for your 64K circuit, it would look like this:
frame-relay cir 64000
frame-relay bc 8000
The value 8000 is derived from the formula:
Bc=CIR*Tc
The default TC is 0,125, which equals 1/8 of a second. You might want to check the following document for an excellent explanation of the different values, and how they interact:
Frame Relay Traffic Shaping
http://www.internetworkexpert.com/resources/01700368.htm
By the way, once you have your circuit in place, you can use the ‘show frame-relay map’ command to verify that you are actually getting the bandwidth that you have ordered. In the output of that command, look for the line ‘BW=’, that is the bandwidth configured.
ISP’s sometimes ‘forget’ to set that bandwidth correctly…
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