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We just bought two HP 5500-24G-4SFP beasts and I'd like to properly integrate the switches into Nagios. Most of our current monitoring polls actively via SNMP so I figured it would be wise and use the occasion to get snmptrapd/snmptt working so we can receive SNMP traps in Nagios.

Now I read this in the device's Network Management and Monitoring Configuration Guide:

Enable SNMP traps only if necessary. SNMP traps are memory-intensive and may affect device performance.

My question is, while the statement might be true, why would one not use SNMP traps on such a core device of one's network and what kind of performance impact is to be expected? I'm struggling to find a sane definition of "necessary" in this context.

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1 Answer 1

up vote 2 down vote accepted

Traps trade consuming memory and processing resources on the switch for reduced network usage.

  1. Counters, status registers etc on network gear
  2. Polling and tracking the above
  3. Taking actions

Doing (2) and part of (3) on the switch means less network traffic querying SNMP MIBs. This would be a win if you have one piece of network gear at a remote location over an expensive link and you want to monitor things that don't trigger actions often.

For a local network a few traps for things that rarely trigger events can be a win as well when the underlying counter or registers are not already being queried for other purposes.

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I understand that but this doesn't explain why HP basically advises against properly monitoring your core equipment which seems weird for a device that costs 3500ish USD. If their point is more like "only enable those traps which you are actually interested in as traps consume memory and CPU and might negatively affect the device's performance" then I would have understood, but it reads like they generally discourage the use of all SNMP traps. I'll accept your answer since I must assume that this is not the case and my interpretation of their ambiguous statement is wrong :-) –  Adrian Frühwirth Jun 17 at 7:21

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