We are using this technique for the default route for a pair of routers
using HSRP where both are connected to the WAN through Ethernet emulation.
Since Ethernet isn't point-to-point (although the circuit may have no other
hosts) it is probable that if the remote WAN FastEthernet dies (or anywhere
in between), HSRP will not kick in because the local Ethernet connection is
still alive and talking to its first link - that being a hub/switch, foirl
or whatever.
Therefore, a "normal" default route to the next hop won't work 'cause it is
on a network that is configured and still alive on the local router. Even
if the remote router dies, the local router still thinks the route is good
because the local interface is up. Keepalives only go as far as the
hub/switch.
Therefore, we depend on OSPF redistributing the "normal" default and we
configure a floating static to the neighbor HSRP router. If the link fails
anywhere, OSPF routes are lost and then the floating static comes up. The
neighbor router has full routes as it is configured the same way.
The behavior showed up in the lab. We failed the remote router interface
and HRSP didn't work so we had to think on that one for awhile. Figuring
our why the default route didn't drop out of the routing table was
interesting since it is normal that if a destination isn't reachable then
the route should disappear.
On the interior interfaces we are using EIGRP and redist that into OSPF. We
don't redist OSPF into EIGRP so we don't get any routing loops. However,
using distribute lists should fix any routing loops you might have.
Kevin Wigle
----- Original Message -----
From: "Chuck Larrieu" <[EMAIL PROTECTED]>
To: "Phil Barker" <[EMAIL PROTECTED]>; "Stull, Cory"
<[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Tuesday, January 09, 2001 11:59 AM
Subject: RE: ip route question
> I agree that the design itself is open to question. I am not so sure that
> router_a is going to know what to do.
>
> Chuck
>
> -----Original Message-----
> From: Phil Barker [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, January 09, 2001 8:50 AM
> To: Chuck Larrieu; Stull, Cory; [EMAIL PROTECTED]
> Subject: RE: ip route question
>
> Hmmmm,
> Not so sure if it is a good idea though !!!
> I tried this one time at work where I inserted a
> static route to a network more than one hop away,
> although I had "re-distribute static" on the EIGRP
> configured router it created a wonderful little
> routing loop and I went home late again.
>
> Regs,
>
> Phil.
>
> --- Chuck Larrieu <[EMAIL PROTECTED]> wrote: > The
> answer is that on Cisco equipment, anyway, one
> > can configure a static
> > route to go to a directly connected interface, or to
> > any network that
> > appears in the routing table.
> >
> > It looks like, in your case, you want something like
> > this:
> >
> > Router_C
> > i.p. route 0.0.0.0 0.0.0.0 router_A_address ( since
> > this is internet
> > traffic )
> >
> > I am assuming router A then knows what to do with
> > the traffic.
> >
> > HTH
> >
> > Chuck
> >
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED]] On Behalf Of
> > Stull, Cory
> > Sent: Tuesday, January 09, 2001 7:58 AM
> > To: '[EMAIL PROTECTED]'
> > Subject: ip route question
> >
> >
> > I remember reading somewhere that when you add an IP
> > route the ip address of
> > the next hop doesn't necessarily need to be the next
> > hop or even on the same
> > subnet..?
> >
> > Reason for asking
> >
> >
> > I want RouterC to have to go to RouterA before going
> > out routerB to the
> > internet because routerA and routerB are on same
> > ethernet segment with a
> > websense internet filter on that segment being used
> > to filter internet
> > traffic. Right now RouterC traffic goes
> > straight to routerB to
> > internet and doesn't get filtered through the
> > websense filter.
> >
> > Comments?
> >
> > Thanks in advance as always.
> > Cory
> >
> >
> >
> > (central site)
> > RouterA \
> > \
> > \
> > \
> >
> >
>
RouterB--------------------------------------------------------------------\
> > ------------------------------------RouterC(remote
> > site)
> > (central site) \
> > \
> > \
> > \
> > Internet
> >
> >
> > _________________________________
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