[Xorp-hackers] OSPF stuck in Exchange state.

[Atanu Ghosh]

Hi,

If you think that the retransmission code has failed then in the method
"doit()"

    bool doit() {
	debug_msg("retransmission: %s\n", str().c_str());
	return  _rcb->dispatch();

    }

Change the debug_msg to "fprintf(stderr," while an adjacency is in the
state Exchange the master side should be retransmitting every second.

     Atanu.

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

    Ben> Atanu Ghosh wrote:
    >> Hi,
    >> 
    >> This behaviour is correct.
    >> 
    >> Interfaces of type broadcast and NBMA will elect a DR and BDR if
    >> there are enough neighbours. In this case only the DR and BDR
    >> need to form full adjacencies with all neighbours, the other
    >> neighbours will stay in the 2-Way (TwoWay) state.
    >> 
    Ben> Thanks for that info, that makes sense.  Before asking my next
    Ben> question: I did read through the rfc, but don't see any reason
    Ben> for links to be stuck in the Exchange state.  However, after
    Ben> leaving it overnight, it's still like that.  The connection
    Ben> between the routers is an emulated 128kbps sat link (1.5seconds
    Ben> round-trip), and it drops packets occassionally (or more often
    Ben> if sent pkts at rates above 128kbps).  This sat acts like an
    Ben> ethernet bridge to other routers connected to it.  Maybe there
    Ben> is some retransmit logic that isn't quite right?

    Ben> If I restart Xorp a few times, it will eventually come up with
    Ben> all in 'full' state (on router 12, which appears to be the
    Ben> master) . I see hellos from the nodes in Exchange state, so it
    Ben> seems they should be able to communicate.

    Ben> [root at lf1016-55 lanforge]# tcpdump -n -i 2.16.2 tcpdump:
    Ben> verbose output suppressed, use -v or -vv for full protocol
    Ben> decode listening on br0, link-type EN10MB (Ethernet), capture
    Ben> size 96 bytes 09:04:32.113138 IP 99.1.1.12 > 224.0.0.5: OSPFv2,
    Ben> Hello, length: 68 09:04:32.493651 IP 99.1.1.11 > 224.0.0.5:
    Ben> OSPFv2, Hello, length: 68 09:04:32.506866 IP 99.1.1.10 >
    Ben> 224.0.0.5: OSPFv2, Hello, length: 68 09:04:32.541082 IP
    Ben> 99.1.1.2 > 224.0.0.5: OSPFv2, Hello, length: 68 09:04:32.911437
    Ben> IP 99.1.1.6 > 224.0.0.5: OSPFv2, Hello, length: 68

    Ben> 5 packets captured 10 packets received by filter 0 packets
    Ben> dropped by kernel

    Ben> This is for router '2'.

    Ben> [root at lf1016-55 lanforge]# xorpsh Welcome to XORP on lf1016-55
    Ben> root at lf1016-55> show ospf4 neighbor Address Interface State ID
    Ben> Pri Dead 99.1.1.12 2.16.2/2.16.2 Exchange 127.1.0.12 128 38
    Ben> 99.1.1.10 2.16.2/2.16.2 TwoWay 127.1.0.10 128 39 99.1.1.11
    Ben> 2.16.2/2.16.2 Exchange 127.1.0.11 128 39 99.1.1.6 2.16.2/2.16.2
    Ben> TwoWay 127.1.0.6 128 39 99.1.1.9 2.16.2/2.16.2 TwoWay 127.1.0.9
    Ben> 128 34 99.1.1.3 2.16.2/2.16.2 TwoWay 127.1.0.3 128 37 10.1.2.1
    Ben> 1.2.2/1.2.2 Full 127.1.0.1 128 34 10.2.3.3 2.3.2/2.3.2 Full
    Ben> 127.1.0.3 128 35 10.2.4.4 2.4.2/2.4.2 Full 127.1.0.4 128 32
    Ben> 10.2.5.5 2.5.2/2.5.2 Full 127.1.0.5 128 37 10.2.6.6 2.6.2/2.6.2
    Ben> Full 127.1.0.6 128 38 10.2.9.9 2.9.2/2.9.2 Full 127.1.0.9 128
    Ben> 33 10.2.10.10 2.10.2/2.10.2 Full 127.1.0.10 128 38
    Ben> root at lf1016-55> quit [root at lf1016-55 lanforge]#

    Ben> Here is the 'show ospf neighbor' for router '12':

    Ben> Welcome to XORP on lf1016-55 root at lf1016-55> show ospf4
    Ben> neighbor Address Interface State ID Pri Dead 99.1.1.3
    Ben> 12.16.12/12.16.12 Full 127.1.0.3 128 34 99.1.1.10
    Ben> 12.16.12/12.16.12 Full 127.1.0.10 128 34 99.1.1.2
    Ben> 12.16.12/12.16.12 Exchange 127.1.0.2 128 34 99.1.1.11
    Ben> 12.16.12/12.16.12 Full 127.1.0.11 128 34 99.1.1.6
    Ben> 12.16.12/12.16.12 Full 127.1.0.6 128 34 99.1.1.9
    Ben> 12.16.12/12.16.12 Full 127.1.0.9 128 31 10.1.12.1
    Ben> 1.12.12/1.12.12 Full 127.1.0.1 128 30 10.9.12.9 9.12.12/9.12.12
    Ben> Full 127.1.0.9 128 39 10.10.12.10 10.12.12/10.12.12 Full
    Ben> 127.1.0.10 128 33 10.11.12.11 11.12.12/11.12.12 Full 127.1.0.11
    Ben> 128 33 10.12.13.13 12.13.12/12.13.12 Full 127.1.0.13 128 34
    Ben> 10.12.14.14 12.14.12/12.14.12 Full 127.1.0.14 128 33
    Ben> 10.12.15.15 12.15.12/12.15.12 Full 127.1.0.15 128 34
    Ben> root at lf1016-55>


    Ben> Thanks, Ben

    Ben> -- Ben Greear <greearb at candelatech.com> Candela Technologies
    Ben> Inc http://www.candelatech.com