Posted on November 9, 2020 9:31 pm
 |  Asked by Kevin Malone
 |  131 views
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Is there application built in bash that will allow you to monitor live throughput of an interface?  I know you can do a “sh int ethX” within eos to show the 5 minute average throughput of an interface.  But if i’m making changes to routing it would be nice to see live values instead of waiting for a 5 minute average.

I’ve tried installing the epel repo under bash and installing a couple applications but they show so many missing dependancies, getting them installed seems like a pita.  Is there something built-in that will doing something like nload?

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Posted by Shawn Rogers
Answered on November 9, 2020 10:05 pm

Hi Kevin,

Would you be able to set the load-internal to 2 seconds on the interface(s) you would like to monitor then use the EOS CLI watch command to refresh the output of the command "show interfaces counters rates | egrep -i 'etX|port'?

In the example below I set the load interval on interface et3/1 to 2 seconds then I used the watch command to monitor the input/output

conf
int eth 3/1
load-interval 2
exit
watch 1 diff show interfaces counters rates | egrep -i 'et3/1|port'

Every 2.0s: CliShell -s ar -p 15 -c show interfaces counters rates | egrep -i 'et3/1|port' Mon Nov 9 21:51:00 2020

Port Name Intvl    In Mbps    %            In Kpps  Out Mbps   %        Out Kpps
Et3/1           0:01     985.6         10.0%   81             23.0            0.3%   41

If you need to monitor more than 1 interface we just need to change the load internal on the other interface(s) and add the new interface(s) to the egrep

For example, if we would also like to monitor interface et3/4

conf
int eth 3/4
load-interval 2
exit

watch 2 diff show interfaces counters rates | egrep -i 'et3/1|et3/4|port'

Every 2.0s: CliShell -s ar -p 15 -c show interfaces counters rates | egrep -i 'et3/1|et3/4|port' Mon Nov 9 22:01:05 2020

Port Name   Intvl    In Mbps    %            In Kpps  Out Mbps   %           Out Kpps
Et3/1           0:01       1048.3      10.6%    86            24.2              0.3%    43
Et3/4           0:01       0.0            0.0%      0              390.3           4.0%    32

 

 

 

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Posted by Roberto
Answered on November 9, 2020 10:07 pm

Hello,

You can change the load-interval of any interface from 5 minute load-interval to as low as 5 seconds.

I'm not sure if you also tried "show interface counter rate | nz" >> this command will show you the incoming and outgoing traffic rate of all the interfaces.  You can "watch show interface counter rate | nz" to see the counters increment as it occurs.

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Posted by Kevin Malone
Answered on November 9, 2020 10:56 pm

Thanks for the help.  I think "watch 1 diff show interfaces counters rates | nz" will give me what i'm looking for with lower load intervals.  My question being what is the downside to haveing lower load intervals?  Does this put more pressure on the management plane cpu?

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Posted by Roberto
Answered on November 9, 2020 11:18 pm

Hello,

 

Lowering the load-interval will not add additional CPU load nor it would have any CPU affect at all.

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Posted by Kevin Malone
Answered on November 10, 2020 5:48 pm

if load interval has no affect on system resources then why is the default set to 5 minutes?  Wouldn't lower load intervals provide more granular results and be the prefered default?

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Posted by Alexis Dacquay
Answered on November 17, 2020 6:31 pm

Kevin,
Maybe rephrasing what Kevin said, it has an impact: the agents have to interrogate the hardware more often.
It is fine, it can deal with it. But it is unnecessary load, even if it's minimal. We are trying to stay optimal and frugal so that the switch gets more cycle for other things.
Personally I do like to set it from 5 minutes to 5 seconds too, but on large scale devices (over thousand port per switch), it can make more sense to economise resources and set it low only where necessary.
On devices with fewer ports it might not make a difference.

Have you considered Telemetry, to stream yo statistics out of the switch to a collector?

Regards,
Alexis

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