CIR on MPLs link

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May 5th, 2008
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hi have MPLS link at site.

Telco says they have CIR of 2748KB on there router.

I check my router it shows


MTU 4470 bytes, BW 3000 Kbit, DLY 20000 usec,

ATM0/0/0 is up, line protocol is up

MTU 4470 bytes, sub MTU 4470, BW 1544 Kbit, DLY 20000 usec,

ATM0/0/1 is up, line protocol is up

MTU 4470 bytes, sub MTU 4470, BW 1544 Kbit, DLY 20000 usec,

so 3 ATM int have 3 different BW.

which should i look for


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mahesh18 Tue, 05/06/2008 - 10:30
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Any body can answer my question please



soray Tue, 05/06/2008 - 13:06
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Hello Mahesh18 ~

When they say CIR. They are talking about the committed rate that is guranteed. That means if any of your traffic exceeds that isn't guranteed.


murphymd Wed, 05/07/2008 - 08:18
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It appears they have the 2 subinterfaces created into one IMA group. BW 1544 x 2. IMA BW = 3000..

mahesh18 Wed, 05/07/2008 - 10:51
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thanks for reply

so atm0/0 and atm 0/1 are subinterfaces?

Pravin Phadte Thu, 05/08/2008 - 05:59
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BW which is show in the ineterface output depends on the clocking.

For ex if you have T1 link on S0/0 and you give show int se0/0 you will see the BW as 1544k This is default for T1.

Now if you want to change the bw on the ser0/0

go to

config t

int ser0/0

bandwidth ?

and apply the rate you need.

check the running configuration on the ATM interface.

if you can paste it in would be better.

mahesh18 Thu, 05/08/2008 - 06:43
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Hi tahnks for reply

so i pasted the running-config let me know

what it is?

Also when we do sh int it always show default

config no matter it is serial line or ATM interface.In order to check bandwidth getting from telco we should always see running config?

Thanks a lot

Pravin Phadte Thu, 05/08/2008 - 07:24
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HI mahesh,

The reason why you are seeing the bandwidth while giveing the show command is because of the configuration on the interface with the command Bandwidth.

This command does not make any diffrence with the bandwith provided by the telco. You can set it to 64 also. This can be used mostly to calculate the bandwith in 2 ways.

You have 2 ATM links ATM0/0/0 and ATM0/0/1 each have T1 bandwidth 1544.

In simple words they are been bundled just like a multilink. The interface you need to look for bandwith is ATM0/IMA0.777.

This interface will carry two T1 Bandwidth ATM0/0/0 and ATM0/0/1.

total bandwith is not seen in the running config but in the show output. Do not change the configuration on the router for badnwith command if you are running EIGRP one reason why it is configued is because EIGRP metric are BW.

This command will help you in inetrface output.

mahesh18 Sat, 05/10/2008 - 11:18
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Thanks for reply,

so running config for ATM0/IMA0.777.

shows bandwidth 3000

so thats the bandwidth link is using now?

please answer


waleed_amer Sat, 05/10/2008 - 11:45
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the BW configured for the interface or for the ima not used for data transmission, the data will transfer with physical layer rate (ex. DSL speed that the telecom company provide you and this BW configuration for some calculations on the router like EIGRP, QoS.

Regards, W.Amer

Pravin Phadte Mon, 05/12/2008 - 01:43
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if the command BW is not available still you will have 3 MB. Its used for EIGRP as said and for monitroring purpose.

The command Bandwidth does not make any deffrence in the BW on the link.


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