I’ve done it. Not hard at all
but expensive. Demand Poll takes a lot of cycles. This script is
executed out of the ESE.Automation when an event indicating a failed poll is
received. A ruleset kicks it off as a background action.
goshawk2#cat RouterDP.sh
#!/bin/ksh
Hostname=${1}
Date=`date`
echo ${Date} function off
>>/opt/webmon/RouterDP.log
usr/OV/bin/nmdemandpoll
${Hostname} >>/opt/webmon/RouterDP.log &
One problem is that SNMP doesn’t
really have any better priority or architectural power than ICMP. I
actually used the process when SNMP polling had a problem with late arriving
responses on a slow and overloaded processor. It’s an architectural
fact that ICMP and SNMP are low priority and allowed to be thrown away. NetView
compensates by its geometrically increasing waits on retries and the ability to
customize retries and wait time by device.
I quit using the script once we had the
problem figured out. The overhead of Demand Poll actually made things a bit
worse.
I’d go for solving the root
cause. Manipulate the timeouts and retries for ICMP. Make sure your
NetView box has enough resources. Check the delays at the routers and
switches to see if there’s a bad card tying up traffic. Etc.
The other alternative is to look into the
IBM Tivoli Switch Analyzer. It automates the follow-up of failed polls
and its slightly delayed follow up to the failed ICMP often clears the
condition.
Using an inline action is a VERY BAD
idea. Your entire rules processing waits for the demand poll to finish. The
system can totally bog down; note that my background script spins the demand
poll off as an independent process because it was single threading the
background action processing.
-----Original Message-----
From: owner-nv-l@lists.us.ibm.com
[mailto:owner-nv-l@lists.us.ibm.com] On
Behalf Of Kumar Vanka
Sent: Thursday, June
23, 2005 8:48 PM
To: nv-l@lists.us.ibm.com
Subject: [nv-l] Status Polling
I'm using ICMP for status
polling in our environment. However, due to several factors, we're getting many
false positives. One of these factors is that ICMP has a low priority in our
environment. Is it possible to configure netmon so that if the ICMP status poll
shows that a node is down, it can then do a demand poll using SNMP?
Based on my research, it
appears this is not possible. So, I'm considering modifying my ruleset
to use an inline action to run nmdemandpoll. Is this a good option? Or,
are there other options that I'm not considering?
Thanks.
- Kumar Vanka
ESM Architect
Invenio, Inc.