[Xorp-users] bug: OSPF designated router holds routes from disconnected router

[Mellen, Ivan]

Hi,

 

I'd like to report this XORP bug: OSPF designated router holds routes
from disconnected router.

 

Bug description: The OSPF router A holds routes from another OSPF router
C  long time after that router C has disconnected, even though A  knows
that OSPF neighbor C is down. This happens only if the OSPF router A is
the Designated Router.

If OSPF router A is alone (has no neighbors) after router C disconnects,
this bug does not appear.

 

This test used unmodified XORP v1.8.5 with CORE 4.3 (20120307) running
on 32 bit UBUNTU 11.04

 

For the details, required configuration files and CORE scenario please
see:

http://www.xorp.org/bugzilla/show_bug.cgi?id=120

 

Timeline (min:sec):

 

0:00  CORE simulation started

0:56  Injected route 10.41.1.0 from router C node appears  in router A
and router B

2:00  router C node interface to LAN manually  brought down (ifconfig
eth0 down)

2:35  router B (non DR node) properly withdraws injected route
10.41.1.0/26 from its kernel table.

      router A (Designated router) detects that router C neighbor is
down, but keeps the  injected route for another hour (even though it
knows  that next hop 10.254.10.4 is down)

 

      The console log below shows router A incorrectly maintain a route
to 10.41.1.0/26    via a Down neighbor (10.254.10.4).  The state below
can persist up to 1 hour   (External Route ads expire after 3600
seconds).

 

 

    root at n1:/tmp/pycore.34570/n1.conf# /usr/local/xorp/sbin/xorpsh

    Welcome to XORP v1.8.5 on n1

    Version tag: 00000000  Build Date: 2012-12-05 11:26 32-bit

    root at n1>  show ospf4 neighbor detail

      Address         Interface             State      ID
Pri    Dead

    10.254.41.14     eth2/eth2              Full      10.254.41.14
0     31

      Area 0.0.0.0, opt 0x2, DR 10.254.40.131, BDR 0.0.0.0

      Up 00:05:38, adjacent 00:04:53

    10.254.10.4      eth2/eth2              Down      10.254.10.4
0     0

      Area 0.0.0.0, opt 0, DR 0.0.0.0, BDR 0.0.0.0

      Up 00:05:37

 

    root at n1>  show route table ipv4 unicast ospf detail

    Network 10.11.67.128/26

        Nexthop        := 10.254.41.14

        Interface      := eth2

        Vif            := eth2

        Metric         := 1

        Protocol       := ospf

        Admin distance := 110

    Network 10.41.1.0/26

        Nexthop        := 10.254.10.4

        Interface      := eth2

        Vif            := eth2

        Metric         := 3

        Protocol       := ospf

        Admin distance := 110

    root at n1> 

 

 

10:00 router B LAN interface manually brought down (ifconfig eth2 down),
router

A remains alone on VND network

10:35 router A  properly removes injected route

      router A does not act as DR when alone ?

 

      after reconnecting  router B back to LAN network, injected route
10.41.1.0/26 does not appear again

 

 

To prove that Designated Router status is causing this bug, please
comment line 56 in the xorp2.conf file and restart the simulation. This
will allow router B to participate in the DR selection and to win it.
Once the router B becomes the DR, it will incorrectly main a route to
10.41.1.0/26 via a down neighbor after the router C node has
disconnected. On the other hand, the router A node will now properly
remove this route.

 

 

Has anybody experienced similar behavior of the OSFP router?

 

Thanks,

 

Ivan 



The information contained in this e-mail message is PRIVATE. It may contain confidential information and may be legally privileged. It is intended for the exclusive use of the addressee(s). If you are not the intended recipient, you are hereby notified that any dissemination, distribution or reproduction of this communication is strictly prohibited. If the intended recipient(s) cannot be reached or if a transmission problem has occurred, please notify the sender immediately by return e-mail and destroy all copies of this message. 
Thank you. 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ICSI.Berkeley.EDU/pipermail/xorp-users/attachments/20130103/8d17b38c/attachment.html