Monitor router interfaces

[sbaviswa]

Hi

We have a set of cisco routers being monitored via snmp v3. The routers have a couple of E1 Serial cards & a couple of ISDN backup interfaces.

Using the cfgmaker command, we are able to get all the interface details of the cisco router & configure them manually in nagios core config manager for the port status using the OID = ifOperStatus.<i/f no.> equivalent to .1.3.6.1.2.1.2.2.1.8.<i/f no.>

Everything seems to be in order until there is any restart of the router which shuffles the interface numbers.

Has anyone come across this issue.

To put it in another way, while configuring a cisco router using snmp v3, what interfaces to consider for getting the status persistently. Also is there any way where the interface nos. realigns itself to the changed values.

Regards
SBA-Viswa

[abrist]

You should contact Cisco, as this should not happen with their devices. The only way that these should change is when you are physically changing the number of interfaces which will force the device to re-poll the interfaces and assign oids. It could be related to a configuration error, or possibly a bug.

As this issues is directly related to the Cisco hardware and its snmp support, they *should* have the answers for such a strange problem.

[sbaviswa]

Thanks for your reply
The fact is when we use cfgmaker for a router for example having 2 BRI interfaces w/2 channels, 2 serial interface cards, we will get something like this

Interface 1
Target[192.168.0.10_1] Gigabit Ethernet 0/0
Interface 2
Target[192.168.0.10_2] Gigabit Ethernet 0/1
Interface 3
Target[192.168.0.10_3] Serial 0/0/0
Interface 4
Target[192.168.0.10_4] BRI 1/0
Interface 5
Target[192.168.0.10_5] BRI 1/0:1
Interface 6
Target[192.168.0.10_6] BRI 1/0:2
Interface 4
Target[192.168.0.10_4] BRI 1/1
Interface 5
Target[192.168.0.10_5] BRI 1/1:1
Interface 6
Target[192.168.0.10_6] BRI 1/1:2
Interface 7
Target[192.168.0.10_7] Null 0
Interface 9
Target[192.168.0.10_9] Loopback 0
Interface 10
Target[192.168.0.10_10] Serial 3/0:1
Interface 11
Target[192.168.0.10_11] Serial 3/0:2
Interface 12
Target[192.168.0.10_12] Serial 3/0:3
Interface 13
Target[192.168.0.10_13] Serial 3/0:4
Interface 14
Target[192.168.0.10_14] Dialer1
Interface 15
Target[192.168.0.10_15] Dialer2
Interface 16
Target[192.168.0.10_16] Dialer3
etc
etc

The physical serial interfaces like Serial 0/0/0, etc are consistant. But the interfaces like Serial 3/0:1, 3/0:2, etc are changing.
From the router diagnosis end, the network people say, it is the common phenomenon when the router restarts, the interface nos. of virtual interfaces like :1, :2, etc will change.
Hence this trouble in configuring nagios in a stable way.

Request your help & suggestion.

Regards
SBA-Viswa

[slansing]

As Andy had mentioned this is out of the ordinary, this is not the normal behavior for a device like this, unless it has been modded to do so, or there is something else going on. What model is the router? We may not be able help beyond that as Nagios XI is not meant to dynamically find the new name of a router's interfaces, and then come back and change it's own configuration files on the fly.

[sbaviswa]

I do understand that configurations cannot be changed dynamically, but one thing I would like to understand is --> "Is my way of configuring a router for monitoring CORRECT?" ie., by running cfgmaker, noting the interfaces & creating the services for the required ports.I had to do this manually because nagios has not yet provided a way to add snmp-v3 enabled switches/ routers in the wizard provided.

However for your information the router's model is Cisco 3845.

Regards
SBA-Viswa

[slansing]

Yes that looks like a okay method, are you able to monitor them correctly in this fashion? On a side note, I believe one of our developers is working snmp v3 into the wizard/plugins for a future release!

[sbaviswa]

Good to hear on development progress of snmpv3 integration into the wizard.

Yes, as I said earlier, until otherwise there is a restart of router causing the shuffling of interfaces, this method seems to be good enough.

Thanks
SBA-Viswa