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KdgDev
Asked: 2011-01-06 15:26:49 +0800 CST

Cisco router not receiving OSPF updates

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Or at least, that's what I think is happening. There doesn't appear to be a debug command for this, or to see if something is in the routing table.

I'm testing out this setup in Packet Tracer. I have 3 routers and a webserver

From left to right, you have: Webserver -> Router1 -> Router2 -> Router3

Router1 and Router2 can succesfully ping WebServer. Router3 cannot.

Router2 has a default gateway set, to send all not-recognized data through its serial interface to Router1.

Like this: ip route 0.0.0.0 0.0.0.0 Serial 0/0/1 Serial 0/0/1 being the connection to Router1

Router2 and Router3 have OSPF configured. From their "show run":

Router2:

router ospf 1
 log-adjacency-changes
 passive-interface Serial0/0/1
 network 10.1.1.0 0.0.0.3 area 0
 default-information originate
!

Router3:

router ospf 1
 log-adjacency-changes
 network 10.1.1.0 0.0.0.3 area 0
 passive-interface FastEthernet0/0
!

I was under the assumption that setting default-information originate on Router2 would give Router3 the needed information. What's going wrong here?

The interfaces are up. Ip addresses are with mask-range, clock rate is set at correct end. I don't know what else to check.

EDIT: I was going to post a screenshot, but now it's working all of the sudden. I opened the PKT file, repositioned stuff so the labels would be clear, took the screenshot and then ran the test again, to see where the real-time analyzer said the mistake was. And it worked.

I'm sorry to have taken your time over this. I'm flabbergasted over this.

router cisco ospf

1 Answers

  1. Best Answer

    Is FastEthernet0/0 (on Router3) the link to Router2? If so, the "passive-interface FasthEthernet0/0" is the main reason it's not working.

    In OSPF terms, a "passive interface" is an interface that matches one (or more) of the network ranges specified in the "router ospf N" section, but does not send OSPF announcements.

    Sending OSPF announcements is necessary to form OSPF adjacencies between routers on a network (be it a point-to-point link or a broadcast network with multiple routers). Having OSPF adjacencies formed is required for OSPF route exchange to happen.

    As far as debugging OSPF, there's quite a few things under "debug ospf", I don't have an IOS handy, but I am pretty sure you can get the kit to log all LSAs sent as well as received (or, indeed, all OSPF state changes that happen).

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