Keep in mind, netmon has a list of things to check status on. If you only had
one node discovered, and it was on a 1 second status poll (theoretical, don't
really try that) it would notice much faster than if it were on a 3 minute poll
with 100 nodes.
Netmon would definately notice it up at the next schedule poll of the device.
There is a netmon command to dump the ping list (and the SNMP list) to see if
you are backing up on status polls or whether you've got cycles to spare. The
man page for netmon has the proper flag (netmon -a 11 / 12 are for ping lists)
if you issue netmon -a 12 and then look at the netmon.trace file, it will tell
you how many nodes are in line to be pinged.
We've all observed the behavior you are describing, but it is usually
attributed to being anxious to see the node turn green again. Now, if the
status poll time passes, and the node doesn't turn green, then you do have a
problem. If you want to know when the next status poll for a node occurs, use
ovtopodump -rl <resourcename>.
Hope that helps.
Scott Barr
Distributed Network Engineer
CSG Systems Inc.
Phone: 402-431-7939
Fax: 402-431-7413
scott_barr@csgsystems.com <mailto:scott_barr@csgsystems.com>
________________________________
From: owner-nv-l@lists.us.ibm.com on behalf of Freeman, Michael
Sent: Thu 10/7/2004 7:42 PM
To: nv-l@lists.us.ibm.com
Subject: RE: [nv-l] how does netmon interact with the ARP cache?
If this is the case, then how come in my simulations when I start an agent, and
then netview notices its down, then I turn it back up, if I ping it right away
the object in netview changes status, if not, it will eventually pick it up
when "it feels like it"
________________________________
From: owner-nv-l@lists.us.ibm.com [mailto:owner-nv-l@lists.us.ibm.com] On
Behalf Of Barr, Scott
Sent: Thursday, October 07, 2004 12:52 PM
To: nv-l@lists.us.ibm.com
Subject: RE: [nv-l] how does netmon interact with the ARP cache?
The arp cache will only store the mac address of the local router that is
forwarding packets on behalf of the IP address you are interested. The real mac
address is not present in the arp table on the router (unless by coincidence,
the router has another interface into the subnet where the device actually
resides). I believe the same would be true for the netview box's arp cache -
it's going to reflect the mac address of the device local to the NetView server
(such as the local router) that can reach the end device IP address.
Short answer: I don't think arp cache has anything to do with it. I could be
wrong.
________________________________
From: owner-nv-l@lists.us.ibm.com [mailto:owner-nv-l@lists.us.ibm.com] On
Behalf Of Freeman, Michael
Sent: Thursday, October 07, 2004 12:25 PM
To: nv-l@lists.us.ibm.com
Subject: [nv-l] how does netmon interact with the ARP cache?
I have noticed that if a device goes down, and then comes back up before netmon
"magically notices it", if you ping the device, the object status will change
in NetView. I assume this is because NetView is somehow monitoring the arp
tables? We are using NetView 7.1.3 on Solaris and I am kind of curious to know
how netmon and the arp cache works. It seemed like in my tests with my network
simulator, If I took down 200 nodes, and then brought them up before netmon's
polling cycle kicked in, that if I pinged every one of them (with a script of
course), about only 10 or so nodes would immediately have their object status
changed in NetView. How does netmon divvy up the workload? Helper threads?
Timeslicing ?
*** Note new e-mail address
--
Michael J. Freeman
Netco Government Services
mfreeman@netcogov.com
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