[Xorp-hackers] OSPF doesn't deal well with changing interfaces/neighbors if not currently in state FULL.

Atanu Ghosh atanu at ICSI.Berkeley.EDU
Fri Oct 12 00:51:02 PDT 2007

>>>>> "Ben" == Ben Greear <greearb at candelatech.com> writes:

    Ben> I notice that if I run xorpsh commands too soon after starting
    Ben> xorp, the OSPF routers get stuck in ExStart state.  However,
    Ben> if I wait till they go to Full state, then it seems to work properly
    Ben> when interfaces & neighbours are changed.

    Ben> Here is output of two stuck routers:


This is how OSPF works, when OSPF is first enabled on an interface the
interface goes into state Waiting for time RouterDeadInterval (default
40 seconds). No DR election or attempt to form adjancies will occur
until this time has expired. The only shortcut is if one of the
neigbhours has choosen itself as the DR and the BDR is zero, or if a
neighbour selects this router as the DR. This delay is to stop any
unnecessary changes of the DR or BDR. Once this initial Waiting state
has passed OSPF will become much more reactive.

I noticed from your trace that there is a hello packet missing at time
[ 2007/10/11 18:44:26 ], so you seem to have some other problems. Plus I
suspect the other router has lost a number of hello messages.

On the bright side from looking at your trace I now understand what is causing
this warning:
[ 2007/10/11 18:44:35  WARNING xorp_ospfv2:19127 OSPF peer.cc:1891 event_neighbour_change ] Unexpected state Waiting


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