From: Eric Shao (ericshao@xxxxxxxx)
Date: Sat Jun 09 2001 - 21:35:38 GMT-3
Jay pinpointed the root cause. Some of the routers had ip classless disabled
and we have other 172.16.x.0 showed up in the ip routing table. As soon as I
put "ip classless", half of the puzzle was solved.
How could the workstation behind the router(say on 10.1.1.0/24 segment)
communicate with 172.16.10.0 network while extensive ping by using
10.1.1.0/24 side router interface as source IP address failed?
Thanks alot!
Eric
----- Original Message -----
From: "Jay Hennigan" <jay@west.net>
To: "Eric Shao" <ericshao@beld.net>
Cc: <ccielab@groupstudy.com>
Sent: Saturday, June 09, 2001 12:53 PM
Subject: Re: Bizzare IP routing behavior
> On Sat, 9 Jun 2001, Eric Shao wrote:
>
> > Routing Protocol: OSPF, default static route(Last Resort of Gateway)
points to
> > a Nokia firewall which runs OSPF.
> >
> > Wks --- Rtr --- Firewall --- DMZ(172.16.10.0)
> >
> > ip route 0.0.0.0 0.0.0.0 IP-of-firwall
> > ip route 172.16.10.0 255.255.255.0 IP-of-firewall (bandaid static route)
> >
> > A workstation behind the Router can ping 172.16.10.10(DMZ). Without the
> > bandaid static route, multiple core OSPF routers' ping/extended ping
packets
> > were simply dropped by the router himself. (debug ip icmp and tcpdump on
> > firewall did not capture any packet), but one OSPF core router was able
to
> > ping the DMZ machine. As soon as the bandaid route was added, ping
worked fine
> > on all the problem routers.(which confirms firewall is not the issue
here)
> >
> > The question is, has anyone ever encountered this problem that appears
default
> > route/Last resort of gateway does not function for the router while,
> > workstations behind the problem router still can get to the destination?
The
> > interim solution for now is to redistribute this bandaid static route
into
> > OSPF core. which is a duplicate effort with the existing default static
> > route.
>
> Are there networks in your system of the form 172.16.xxx.yyy where xxx
> is not equal to 10?
>
> Do you have the global configuration command "ip classless" enabled?
>
> If the answers to the above are "yes" and "no", then that's at least
> part of the problem.
>
> --
> Jay Hennigan - Network Administration - jay@west.net
> NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/
> WestNet: Connecting you to the planet. 805 884-6323
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