I would imagine that your netmon queues are clogged with the 3800
entries in the seed file for awhile. Discover is database and network
access intensive. All the discovery going on is competing with your
regular status polling. But that's only the start.
I suspect that the "!@OID 0" slows things down as well. The netmon
daemon will try an SNMP query on every IP address it finds in the ARP
caches (as I understand it) in order to identify which items are not
SNMP capable. It cuts down on the size of the database but adds
discovery overhead. Hopefully it will only be trying it on the contents
of the 10.*.*.* and 130.*.*.* networks found in the ARP caches of your
routers but that can be a lot of addresses. Without negative entries it
will try every IP address it encounters for SNMP. It depends on what
order the filters are applied and my failing memory says the last test
applied is for the positive range. (Someone please correct me if I'm
wrong. The chart I once prepared on this is lost in the disk clutter.)
The recommended way to do this is to tightly control your seed file
with* negative address ranges*. For example, in my installation we do
not monitor the workstations and all workstation addresses are assigned
by DHCP between xx.xx.xx.135 and xx.xx.xx.254. The routers, switches
and servers we monitor are between xx.xx.xx.1 and xx.xx.xx.134. If the
rules were followed strictly we should be able to start with the
entries !1-9.*.*.*, !10.*.*.135-254 !11-145.*.*.*, !146.*.*.135-254
and !147-255.*.*.* to exclude all workstations. (Reality is that I have
about 100 entries to just exclude the various DHCP ranges by subnet.)
The best recommendation you can find in the archives is to discover the
network in stages (and with patience). Once you're sure of your address
ranges you can add the "!@OID 0" to cut down the size of the database
and rediscover. The ultimate seed file blocks everything except the
specific devices you know you want to monitor by address range. You pay
in initial configuration time and overhead and save in daily operation.
Javier Morate Guerrero wrote:
Hi,
NetView 7.1.4 FP2 AIX 5.1
I have a seedfile as:
@limit_discovery
10.*.*.*
130.*.*.*
.....
.....
10.71.203.241 #router cisco
10.71.203.242 #router cisco
.....
.....
!@oid 0
.....
(about 3800 lines)
I have active the option: DISCOVERY NEW NODES
My problem:
Netmon is delayed enough, although the machine is to less of
50% of CPU. If I quit DISCOVERY NEW NODES, netmon is precise. What's
happening?
Un saludo,
Francisco Javier Morate Guerrero
Dpto. Gestión de Sistemas
Carrefour España
jmorate@carrefour.com
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