link utilization

Answered Question
Sep 18th, 2008
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hi every body!

I just want to know if following is correct method to find link utilization:

considering only transmission link i.e tx


link speed= 100 Mb

Number of bit traveling down the transmission line at certain time T1=10Mb

utilization= 10/100= 0.01 or 10 percent

so link utilization is 10 percent at T1

thanks a lot!

Correct Answer by Joseph W. Doherty about 8 years 10 months ago

You can't send 10 Mbps down a 100 Mbps link (running at 100 Mbps). Bits are logically modulated at 100 Mbps. What happens is 90% of the time 10 Mbps isn't transmitted. However, physical link utilization would be 10%.


To further confuse, link utilization is often measured by bits contained within packets or frames. A link could be running at 100% physical utilization, but packet or frame bit counting would likely show less than 100%. For instance, on Ethernet, due to frame preambles and interframe gaps, you can't possibly transfer at 100%.

Correct Answer by glen.grant about 8 years 10 months ago

If you look at the show interface command cisco uses the metrics of a percentage of 255 for the link. If it says 65/255 then it is running approx. 25% of the link capacity.

Correct Answer by satish_zanjurne about 8 years 10 months ago


1.It is correct..!!!!


2.Also you can use loading of the interface in "show interface " command.


3.Also see the input rate & output rate in "show interface " command


HTH..rate if helpful...

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Correct Answer
satish_zanjurne Thu, 09/18/2008 - 23:38
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1.It is correct..!!!!


2.Also you can use loading of the interface in "show interface " command.


3.Also see the input rate & output rate in "show interface " command


HTH..rate if helpful...

Correct Answer
glen.grant Fri, 09/19/2008 - 03:31
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If you look at the show interface command cisco uses the metrics of a percentage of 255 for the link. If it says 65/255 then it is running approx. 25% of the link capacity.

Correct Answer
Joseph W. Doherty Fri, 09/19/2008 - 03:39
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You can't send 10 Mbps down a 100 Mbps link (running at 100 Mbps). Bits are logically modulated at 100 Mbps. What happens is 90% of the time 10 Mbps isn't transmitted. However, physical link utilization would be 10%.


To further confuse, link utilization is often measured by bits contained within packets or frames. A link could be running at 100% physical utilization, but packet or frame bit counting would likely show less than 100%. For instance, on Ethernet, due to frame preambles and interframe gaps, you can't possibly transfer at 100%.

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