best frts bc value?

[pottebm]

We have a router with a 256kb circuit going into an mpls cloud and are using frame-relay traffic shaping. Our current settings are cir=250000 and bc=2500. We are not running voip traffic over the circuit or doing any fragmenting. Is a bc of 2500 (Tc=10ms) appropriate or should it be higher?

[smahbub]

Bc=2500 is correct.Tc is obtained by dividing Bc with Cir.So naturally Tc multiplied by Cir gives Bc.Refer the following URL

http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_feature_guide09186a00800e955b.html#wp1071185.

[sundar.palaniappan]

Hi,

CIR * TC = Bc

250000 * .125ms = 31250

As you can see above you Bc is 31250. If you are wondering why the Tc is .125 ms. In Cisco world, the Tc is 1/8th of a second or .125 ms for up to 768k CIR. Hence, you have to configure the Bc accordingly on the router to make sure you do not exceed the CIR at any interval. The Bc is 1/100th of CIR is good for voice traffic to avoid serialization delay. As you do not do voice you can safely use 31250 as your Bc.

HTH

Sundar