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Beginner

How to see the bandwidth usage of router interfaces in real time?

Hello everyone, I want to see the bandwidth usage of router interfaces Cisco 7200 in real time is there a command to see this or maybe a calculation method? I try with SNMP and Netflow but I need the value of bandwidth usage in real time.

 

Thank you veyr much for your help! 

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VIP Advisor

Re: How to see the bandwidth usage of router interfaces in real time?

the sh int xyz command would give you the thru put.  network management platforms typically poll like every 1 or 5 minutes and graph accordingly. alternatively you can run a on demand snmp poller, because snmp can definitely give you the correct thruput OID. what networks management platform are you using/?

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VIP Advisor

Re: How to see the bandwidth usage of router interfaces in real time?

as suggested other post you need monitoring system in place to monitor the intercface using SNMP / Netflow depends your requirement, you want to in real time, you can set the time to poll how soon you want to results, standard to 60secm you can reduce this one, but you see other issue, monitoring system keep polling to busy device. if this is high processing traffic device you see other issues here.

 

what is the reason you looking this in real time ? 

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Hall of Fame Cisco Employee

Re: How to see the bandwidth usage of router interfaces in real time?

You can set load-interval to 30 seconds on the interfaces (default is five minutes), and then you can see the 30 second bandwidth values in the "show interface" output:

  30 second input rate 0 bits/sec, 0 packets/sec
  30 second output rate 0 bits/sec, 0 packets/sec

It's not real-time, but there is nothing that will give you true real-time.  You can also use the txload and rxload meters to determine the bandwidth usage percentage for that same 30 second interval.  You can then use a small tclsh script to calculate that:

 

set res [exec "show int Fa0/0 | inc load"]

regexp "txload (\d+).*rxload(\d+)" $res -> txload rxload

set tx [expr ${txload}.0 / 255.0]

set rx [expr ${rxload}.0 / 255.0]

puts "TX bandwidth percentage is [expr ${tx} * 100.0]%"

puts "RX bandwidth percentage is [expr ${rx} * 100.0]%"

Beginner

Re: How to see the bandwidth usage of router interfaces in real time?

My answer would have been the same as Joe's, as he's correct. One thing I utilize is LibreNMS which can actually poll real-time traffic as quickly as every 0.25 seconds! 
This is a link for reference to one of the guys over there showing how it's done as evidence:

https://community.librenms.org/t/how-to-monitoring-the-interface-in-real-time-librenms-centos7/1084

 

 

Hall of Fame Cisco Employee

Re: How to see the bandwidth usage of router interfaces in real time?

The problem is many of our devices don't update their interface counters except every 5 or 10 seconds.

Beginner

Re: How to see the bandwidth usage of router interfaces in real time?

Oh, this is a good point, fair enough then, I didn't realize this, but at least you can get better than the 30seconds then? Or does cisco only poll every 30seconds making any third party product not be able to do it quicker? :)
Hall of Fame Cisco Employee

Re: How to see the bandwidth usage of router interfaces in real time?

You can poll more frequently with SNMP, understanding that that has an impact on the network element resources.  With the adoption of streaming, model-driven telemetry, this is improving.  Devices are beginning to support on-change telemetry updates for counters so you can have the device push that data to you.  The ASR9K is an example of such a device.  MDT is going to greatly enhance network monitoring operations as the streams can be multiplexed to different consumers thus reducing overall resource impact to the network elements themselves.

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