no response from the host :snmpwalk

Question

I have implemented AgentX using mib2c.create-dataset.conf ( with cache enabled) In my snmd.conf :: agentXTimeout 15

In testtable.h file I have changed cache value as below...

#define testTABLE_TIMEOUT        60

According to my understanding It loads data every 60 second. Now my issue is if the data in data table is exceeds some amount it takes some amount of time to load it.

As in between If I fired SNMPWALK it gives me “no response from the host” If I use SNMPWALK for whole table and in between testTABLE_TIMEOUT occurs it stops in between and shows following error (no response from the host). Please tell me how to solve it ? In my table large amount of data is present and changing frequently.

I read some where: (when the agent receives a request for something in this table and the cache is older than the defined timeout (12s > 10s), then it does re-load the data. This is the expected behaviour. However the agent does not automatically release the local cache (i.e. call the 'free' routine) as soon as the timeout has expired. Instead this is handled by a regular "garbage collection" run (once a minute), which will free any stale caches. In the meantime, a request that tries to use that cache will spot that it's expired, and reload the data.)

Is there any connection between these two ?? I can’t get this... How to resolve my problem ???

Answer 1

Unfortunately, if your data set is very large and it takes a long time to load then you simply need to suffer the slow load and slow response. You can try and load the data on a regular basis using snmp_alarm or something so it's immediately available when a request comes in, but that doesn't really solve the problem either since the request could still come right after the alarm is triggered and the agent will still take a long time to respond.

So... the best thing to do is optimize your load routine as much as possible, and possibly simply increase the timeout that the manager uses. For snmpwalk, for example, you might add -t 30 to the command line arguments and I bet everything will suddenly work just fine.