FAQ:Applications 07

The agent worked for a while, then stopped responding. Why?

There are three basic possibilities:

• the agent has crashed
• it is hanging
• it is temporarily overloaded

Detecting whether the agent has crashed should be fairly straighforward. If you can reliably reproduce this crash (e.g. by sending a particular SNMP request), then contact the coders list for advice. It's the other two cases that are probably more significant.

To tell the difference between these two, try leaving the agent undisturbed for a while, and then probe it using a single 'snmpget' request, specifying a longer timeout (e.g. '-t 120'). If it now responds, then something was probably sending requests (including duplicate retries) faster than the agent could process them, and it was building up a backlog. Try adjusting the timeout period and retry frequency of these client requests, or look at improving the efficiency of the implementation of the relevant MIB objects.

If the agent remains unresponsive (particularly if the load on the system is steadily climbing), then it's probably hanging, and all you can really do is restart the agent. If you can identify what causes this to happen, then contact the coders list for advice.

   FAQ:Applications
   

1. How do I add a MIB?
2. How do I add a MIB to the tools?
3. Why can't I see anything from the agent?
4. Why doesn't the agent respond?
5. I can see the system group, but nothing else. Why?
6. Why can't I see values in the <ENTERPRISE> tree?
7. The agent worked for a while, then stopped responding. Why?
8. Requesting an object fails with "Unknown Object Identifier" Why?
9. Why do I get "noSuchName" when asking for "sysUpTime" (or similar)?
10. Why do I sometimes get "End of MIB" when walking a tree, and sometimes not?
11. How do I use SNMPv3?
12. Why can't I set any variables in the MIB?
13. Variables seem to disappear when I try to set them. Why?
14. Why can't I change sysLocation (or sysContact)?
15. I get an error when trying to set a negative value - why?
16. I get an error when trying to query a string-indexed table value - why?
17. How should I specify string-index table values?
18. How do I send traps and notifications?
19. How do I receive traps and notifications?
20. How do I receive SNNMPv1 traps?
21. Why don't I receive incoming traps?
22. My traphandler script doesn't work when run like this - why not?
23. How can the agent receive traps and notifications?
24. How big can an SNMP request (or reply) be?
25. How can I monitor my systems (disk, memory, etc)?
26. Applications complain about entries in your example 'snmp.conf' file. Why?
27. OK, what should I put in snmp.conf?
28. How do I specify IPv6 addresses in tools command line arguments?