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New Member

Bandwidth statement for FR-ATM

When working with a full T-1, I am just wondering what is the difference between a bandwidth statement of 1544 and 1536. I understand that 1536 comes from 24 channels of 64k, but I don't understand where the 1544 statement comes in hand. Here is the setup where I'm not sure which statement to put in,

ATM statement:

7204VXR router

interface ATM1/0

atm pvc aa bb cc aal5snap 1536or1544 1536or1544 xx inarp yy

FR statement:

2620 router

interface serial 1/0

bandwidth 1536or1544

Thank you!

2 REPLIES
New Member

Re: Bandwidth statement for FR-ATM

1544 is the theorheitcal bandwidth of a T1. As you stated, the 1536 rating is achieved via 24 channels, or DS0's, that increment @ 64 kbps each. I have seen many configs using both 1536 and 1544 as the bandwidth statements, and I haven't seen any complications with either setting used. To be technically correct, use 1536.

Good luck.

Cisco Employee

Re: Bandwidth statement for FR-ATM

The way you get 1544 is

24 channels x 8 bits = 192 bits

Framing bit 1 bit

Total 193 bits

Frames per second x8000

Rate for T1 = 1544000bps

But if you take out the framing bit, 1536000bps.

So effective rate you get is 1536000bps.

Shajith

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