Impact of SNMP polling

Unanswered Question
Oct 5th, 2007

I'm currently using a Cisco 7613 for aggregation of customer T1 circuits. I am terminating approximately 36 DS3s on this device. We use an MRTG type solution for providing a graphical representation of interface utilization for the individual T1 circuits.

This setup has prompted a discussion of whether it better to poll (SNMP) the 7613 for all the interface data or the T1 interfaces on each of the customer T1 routers.

That said, my questions are:

1. What is the standard practice in this situation?

2. Is there a significant impact to 7613 when performing heavy SNMP polling?

3. Is the increase in network traffic significant when polling a large number of remote devices?

Any thoughts or experience with this would be appreciated.

Thanks,

Mike

I have this problem too.
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vijayasankar Fri, 10/05/2007 - 21:46

Hi,

In your scenario, polling the 7613 router for gathering statistics shouldn't cause any problem/overload to the router.

Usually for traffic statistics gathering the nms tools will be polling the device with a constant interval( for example every 5 minutes).

This shouldn't be overhead for the router.

If you are going to poll the customer routers to get the T1 statistics, you are going to carry the polling traffic also over the T1 link to reach the customer to get these statistics.

When you are going to poll all the remote routers, every individual poll is going to traverse via the respective T1 links only. Hence the traffic is load per T1 links is not going to be huge.

The only catch here is, During heavy traffic load over the T1 link, you will be missing the SNMP polls to the customer router.

For traffic statistics the mrtg is just going to query and retrieve very small counter values per interface. This shouldn't be causing any network load or performance impact in your 7613 Router.

Hence It would be better if you poll your 7613 to get these statistics.

Hope this helps

-VJ

mcallahan313 Sat, 10/06/2007 - 08:21

Thank's for the reply. Those were my feelings as well. You've helped to solve an internal debate. :)

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