How LMS 2.5.1 calculate Broadcast Rate??

[kyawzawhtut]

Hi

I am curious about how LMS calculate Broadcast Rate?

Supposing I set 50% threshold and if I get alert for 1GB link, can I say at that time of moment 500MB amount of packets are broadcasted??

That is hell a lot and description given by Cisco manaul not so useful and I only manage to interpret in that way.

Pleae advice me...

Thank You!!

Regards

Kyaw

[Joe Clarke · Accepted solution]

You are correct in your assumption. The broadcast rate is expressed as a percent of total bandwidth. So, on a 1 Gbit/s link, if the broadcast traffic rate exceeds 500 Mbit/s, then an event would be recorded.

[kyawzawhtut]

Hi jclarke

Thanks again for your confirmation. You have been so resourceful in one way or another!!

So now, customer need to worry why so much broadcast going through in their network.

Have a greate day!!

Cheers

Kyaw

[kyawzawhtut]

Hi JClarke and community

Sorry to ask again. I am now a little bit confused( again :( ).

As the BroadcastRate is read from device MIB and compared agaist the threshold setting, I would like to understand the following

1. how often the value in MIB is updated for BroadcastRate

2. how the value is calculated?

e.g 500Mbit/s at that time or for 1 min timeframe?

Please help me. Thank you.

Best Regards

Kyaw

[Joe Clarke]

The rate the MIB objects are updated depends on interface type. In general, assume that interface counters update no frequently than every 10 seconds. This is not true for all interfaces, but you will be safe with this assumption.

The value is calculated using deltas. The polling interval is configurable within DFM. So the rate is calculated over the last polling interval.

[kyawzawhtut]

Thanks for your answer!

But if somebody clear the counter at network device, will there be any effect at LMS as it is using delta value?

Can LMS be able to understand the counter reset and also reset its delta value? I believe there must have some mechanism there to tackle such situation.

So the baseline is that

1. interface packet counter is updated at every 10sec or more

2. LMS pick the value at polling time and calculate the value using deltas

3. if broadcast pkt percentage is more than total pkt set in threshold, DFM will generate alarts.

Is my understanding correct? :D

Cheers!!

[Joe Clarke]

No, clear counters does not affect SNMP counters. Those can only be reset if the device is reloaded. This is per RFC. Counters can wrap, though, and DFM is capable of dealing with that.

Other than that, your understanding is correct.

[kyawzawhtut]

now I really have crystal clear view. thanks for taking time to answer my questions.

Have a Great day!

Cheers.