routing table wierdness

[Mike Iglesias]

In article <1990Jul31.005036.17883 at evax.arl.utexas.edu> bush at evax.arl.utexas.edu (Joe Bush) writes:
>
>	Lately the routing tables on an MicroVAX 3900 running Ultrix
>3.1 have started to include "host" information in the "destination"
>and "gateway" fields produced by the "netstat -r" command. 

You're probably getting ICMP redirects from some system or router.
The 'D' in the flags means that the route should be deleted sometime,
but I think you have to have routed running for the routes to go
away.  The ICMP redirects are usually sent by a router when it
knows a better route to a subnet than you wanted to use.  For
example, you have a router, two systems, and one of them has
two interfaces with a different subnet behind it:

   router ------------------------------ <- net 1
                  |                    |
              system a             system b
                                       |
                                       | <- net 2

If system a just knows the router as it's default route, and the router
knows that net 2 is behind system b, the router would tell system a
via an ICMP redirect that it should route stuff for net 2 via system b.

The reason that netstat -r is taking a long time to run is due to the
lines that look like this:

>129.107.2.91         129.107.2.91         UGHD     0      24         qe0

If you're using nameservers, you're waiting for the nameserver to
try to resolve that address to a name and it can't.  This takes
a while until it times out, gives up, and prints the IP address in
dotted form.

You might look around for a newly installed system, or a recently
booted or (mis)reconfigured router that could be causing the
ICMP redirects.  You also didn't say whether all the host entries in
the routing table are for hosts on the same subnet/ethernet as your
system.  It's possible that something has gotten confused on your
system and it no longer knows what it's local network is.  Some
useful information to see is the output of 'ifconfig qe0', and
what it should be.  Have you tried rebooting your system?



Mike Iglesias
University of California, Irvine
Internet:    iglesias at orion.oac.uci.edu
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