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Community Member

Bandwidth usage in SDM

2811 router with SDM.

The bandwidth usage (monitor, interface) for an interface in SDM is reported as a percentage, but of what? The interface is a FastEthernet, but it's set at speed 10, duplex full.

Community Member

Re: Bandwidth usage in SDM

Does anyone know the answer to this? Does the SDM interface monitoring of bandwidth take into account the "bandwidth" command? As the previous post mentions the speed of the interface in most cases will be 10 or 100 full duplex, and so a percentage of this won't accurately reflect the actual bandwidth usage.

Community Member

Re: Bandwidth usage in SDM

Hey, almost a year and no one can yet answer this.

When I do a "show interfaces ..." on the interface to measure, it does respond with a bandwidth value even though it is not configured on the interface (look for a line that begins with "MTU XXXX bytes").

I've since abandoned this particular issue and have had to resort to running a job that logs into a protected interface and records the show interfaces output (and filters down only the 5 minute input and output rates). With this output, I can generate my own usage statistics.

The next question once you really look at it agian is "What bandwidth is being measured, input, output, both, how".

I've compared the 5 minute in/out numbers to the bandwith chart and it doesn't correspond to either or both.

Example: We have a Multilink IF with BW 3088kbit.

The monitor shows about 60%, input is 1,060,000, output is 600,000

A few minutes later, monitor shows 45%, input is 1,350,000, output is 450,000

It's obviously not input or total, and if it's output then the % is out of whack.

Could it be a funked up sum of these such as in% + out%? It almost looks like an average of the two, although again, the % is out of whack--unless for some reason the Serial IFs that make up our Multilink are half duplex (like).

Community Member

Re: Bandwidth usage in SDM

I've discovered that if it is a full duplex interface, then 100% is the combination of transmit and receive bandwidth i.e. 20 Mbps.

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