[Xorp-hackers] OSPF stuck in Exchange state.

[Ben Greear]

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.
>   
Thanks for that info, that makes sense.  Before asking my next 
question:  I did read through
the rfc, but don't see any reason for links to be stuck in the Exchange 
state.  However, after
leaving it overnight, it's still like that.  The connection between the 
routers is an emulated 128kbps
sat link (1.5seconds round-trip), and it drops packets occassionally (or 
more often if sent pkts at rates above
128kbps).   This sat acts like an ethernet bridge to other routers 
connected to it.
Maybe there is some retransmit logic that isn't quite right?

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

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

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

This is for router '2'.

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

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

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


Thanks,
Ben

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