ATM Interfaces -- Bandwidth command important?

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May 16th, 2007
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Hi all,

Just wondering if setting the bandwidth on ATM interfaces on a Cisco router is important? We have T1 circuits running ATM back to our main site. Right now the routers think the interfaces are capable of 25Mbps.


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sundar.palaniappan Wed, 05/16/2007 - 16:30
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The bandwidth command is used by QOS & routing protocol(s) for metric calculation only. This command alone doesn't do any QOS but when the bandwidth command is configured to reflect the actual bandwidth of the link any QOS performed using policy map QOS works accurately.



Richard Burts Wed, 05/16/2007 - 16:40
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Sundar is pointing you in the right direction in making the point that the bandwidth statement does not change anything about how the interface actually works. So in that sense it is not important. But the bandwidth is used in the application of QOS as he points out. It is also used in calculation of the load on the interface. If you have network management software that reports link utilization, those reports on these interfaces are not accurate and significantly under-report link utilization.




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