link's utilization calculation

[Umesh Prajapati11238]

Hi all,

Its been around a long time but still couldn't find any valid solution for how to calculate interface utilization, let's give you an example -

Last 300 sec input rate = 56792 bits/per sec

Last 300 sec output rate = 146712 bits per sec

input bandwidth utilization = 0.0.2%

Output bandwidth utilization = 0.09%

now let's suppose this is the point-to-point link and we have taken a 10mbps link from the service provider so based on the 10 Mbps link what will be the actual utilization of the link. 

router's interface speed is - 100 Mbps which is configured.

Please help us to calculate it as I'm a little bit confused while calculating it.

Thank you in advance 

[balaji.bandi]

Most cases from in to out 1:4 ratio or more as per i know, you request 1 you get 4 or more results.

in your case depends on how the traffic flowing what the device connected to that port.

• minute input rate 0 bits/sec, 0 packets/sec: The average rate at which we receive packets.
• minute output rate 0 bits/sec, 0 packets/sec: The average rate at which we transmit packets.

[Georg Pauwen]

Hello,

I hope this is what you are after. Basically, you divide the amount of input and output bits by the amount of bits of a 10 or 100Mbps link. In your case, that would be:

Last 300 sec input rate = 56792 bits/per sec -> 10Mbps link --> 56792/10000000 --> 0.0056792%

Last 300 sec output rate = 146712 bits per sec --> 10Mbps link --> 146712/10000000 --> 0.0146712%

Since you have configured 100Mbps links, the actual interface utilization would be even lower:

Last 300 sec input rate = 56792 bits/per sec -> 100Mbps interface --> 56792/10000000 --> 0.00056792%

Last 300 sec output rate = 146712 bits per sec --> 100Mbps interface --> 146712/10000000 --> 0.00146712%

Keep in mind that you are using the default 300 seconds (5 minutes) interval to measure the load. You might want to set the 'load-interval' on the interface(s) to 30 (seconds).

[Giuseppe Larosa]

Hello @Umesh Prajapati11238 ,

the counters are averaged with an exponential formula so that it takes 4 times the load interval to reflect a costant rate  I have seen this this in lab with traffic generator.

so the suggestion from @Georg Pauwen is really wise you should use load interval 30 the minimum value to have more reactive counters.

I think you need to think about the CIR committed rate of 10 Mbps the speed of the physical interface comes into play for other reasons like possible drops caused by bursts of traffic.

Hope to help

Giuseppe

[Joseph W. Doherty]

"now let's suppose this is the point-to-point link and we have taken a 10mbps link from the service provider so based on the 10 Mbps link what will be the actual utilization of the link.

router's interface speed is - 100 Mbps which is configured."

BTW, in a situation, as described above, often it's convenient to use an interface's bandwidth statement to reflect less available bandwidth than the interface physical is capable of.  I.e. you might set the bandwidth statement, in this case, to 10 Mbps.

[Giuseppe Larosa]

Hello @Joseph W. Doherty ,

I was thinking rather of H-QoS with a parent shaper policy-map if the device is a router, the bandwidth command can be useful too it is the reference for QoS and EIGRP so in the end I agree with you !

Have a good day

Hope to help

Giuseppe

[Joseph W. Doherty]

Using a bandwidth statement to "accurately" set bandwidth percentages, in HQF QoS, or determining some IGP metrics, is, agreed, especially valuable!  But, I believe it also impacts an interface's TX and RX load stats, and often SNMP management stations also often use it for graphing/determining "relative" link utilization, I also believe.