RE: [nv-l] OSPF route change detection

["Barr, Scott" <Scott_Barr@csgsystems.com>]

I would not recommend even trying that unless you have a VERY small network.

 

If I understand OSPF correctly, what is going to happen is that when a route change occurs, ALL routers in the OSPF area will reflect the route change. This would mean that as soon as the first router changes, the rest will begin to change and then basically you are duplicating your efforts across many routers.

 

OSPF route changes happen for LOTS of reasons. For instance, if a segment on the back of the router goes down, that triggers an ospf update. When a circuit in a redundant environment fails, that can trigger ospf updates, these happen all the time. Detecting route changes with NetView could get ugly.

 

It's not really an OSPF mib either, it's the IP route table that gets updated through either the OSPF process on the router or someone typing in a static route. There is not that I know of, an OSPF mib you can query, only the MIB-II IP mib. Here is a sample:

 

ip.ipRouteTable.ipRouteEntry.ipRouteNextHop.10.10.54.0 : IpAddress: 192.168.10.21

ip.ipRouteTable.ipRouteEntry.ipRouteNextHop.10.10.55.0 : IpAddress: 192.168.10.21

ip.ipRouteTable.ipRouteEntry.ipRouteNextHop.10.10.60.0 : IpAddress: 192.168.10.21

ip.ipRouteTable.ipRouteEntry.ipRouteNextHop.10.10.61.0 : IpAddress: 192.168.10.21

ip.ipRouteTable.ipRouteEntry.ipRouteNextHop.10.10.62.0 : IpAddress: 192.168.10.21

 

Whether it is OSPF or statically routed or EIGRP or RIP or whatever, it is this table that gets updated and the only way I can think of to track changes is to somehow store these routes locally and check them against the next update when you query the router's IP route table again. Also note that OSPF routing tables are significantly larger because they contain all known routes in the OSPF area. Proceed with caution here. Other comments welcomed since I am not a routing protocol guru, I just play one on TV.

 

-----Original Message-----
From: owner-nv-l-digest@lists.us.ibm.com [mailto:owner-nv-l-digest@lists.us.ibm.com]On Behalf Of Brian Kraftchick
Sent: Wednesday, October 15, 2003 3:01 PM
To: NVList (E-mail)
Subject: [nv-l] OSPF route change detection

Does anybody have a suggestion on what OID to query within an OSPF configured router to determine/notify when a route changes.  I am quite new to understanding the MIB world and Netview for that matter and have the task of setting up a notification system (using Netview as either a "poll"er or trap receiver, along with TEC) to notify our WAN dept. when routes change.  Any ideas ?

 

Thanks in advance !!!

 

Brian Kraftchick

Network Administrator

Old Dominion Freight Line

Ph: (336) 822-5938

Fax: (336) 822-5149

E-mail: brian.kraftchick@odfl.com

Web Site: www.odfl.com