[Xorp-users] Problems with Linux kernel and OSPF ???

[Atanu Ghosh]

Hi,

The scenario that you describe would be perfectly normal if the
connectivity between the "suspect" router and the "adjacent" router is
lost. Although I would expect the "show ospf4 neighbor" to show the
state of the adjacency to be "Down" not "Full". When an OSPF router
loses its adjancencies the LSA database will slowly timeout, however,
the routes will be withdrawn as soon as the adjacencies are lost.

We will require more information to diagnose the problem next time the
problem occurs the output of "show interfaces" and "show ospf4 neighbor"
would be very useful.

XORP tracks the state of interfaces in particular the carrier state. If
OSPF believes that the Ethernet has been disconnected it will stop
attempting to send hello packets. Is it possible that there is a problem
with an interface or cable between the two routers?

	   Atanu.

>>>>> "Aidan" == Aidan Walton <awalton at wires3.net> writes:

    Aidan>    Hi All, I am using xorp in a production environment,
    Aidan> admittedly a small one. I operate a local WISP and xorp is
    Aidan> running on my wireless nodes. I have a very simple
    Aidan> configuration and really I could probably get away with
    Aidan> static routing throughout the entire network, but I wanted to
    Aidan> try xorp and see just how stable it was. However as I expand
    Aidan> the network I am having second thoughts. It is not good at
    Aidan> all when a network goes up in smoke and I can't explain why
    Aidan> or predict when and what the causes are.  The network has
    Aidan> been in operation 24x7 for around 9 months. I am running on a
    Aidan> Linux kernel 2.6.18-4 and for the vast majority of the time I
    Aidan> have no issues. However now for the fourth time I see the
    Aidan> same problem: Suddenly the Linux kernel and the xorp rib
    Aidan> become detached. Normally all routes in the kernel match
    Aidan> those that xorp is generating, receiving and electing as
    Aidan> active. I am running OSPF and the neighbour states remain
    Aidan> 'full' throughout but if I am not mistaken I see ospf hellos
    Aidan> only in one direction (i.e nothing being transmitted from the
    Aidan> router I suspect). The lsdb of OSPF on the suspect and
    Aidan> adjacent routers contain all the routes but they are aging
    Aidan> out slowly on the adjacent router. When I look at the kernel
    Aidan> routes those from OSPF have already vanished.  I can see the
    Aidan> ospf process running on the offending router? and again I can
    Aidan> see the ospf lsdb intact and correct. When I restart xorp the
    Aidan> system recovers and the routes appear in the kernel again. I
    Aidan> suspect a problem with ospf. I tried enabling traceoptions on
    Aidan> the ospf process, but in fact I needed to restart all the
    Aidan> xorp processes before this actually became active. I now have
    Aidan> this running so if/when it happens again I might be able to
    Aidan> offer some more information.  Does anyone have any experience
    Aidan> of ospf begin unstable? any suggestions how I might more
    Aidan> effectively capture some logs from this event. I do not see
    Aidan> any options for logging the fea process. Is there anything I
    Aidan> can enable to help diagnose the issue?  Many thanks, and of
    Aidan> course cheers for the code in the first place.  Aidan
    Aidan> _______________________________________________ Xorp-users
    Aidan> mailing list Xorp-users at xorp.org
    Aidan> http://mailman.ICSI.Berkeley.EDU/mailman/listinfo/xorp-users