[Xorp-users] static qualified next-hop-router problem

[Tuan Hoang]

Yes, that is correct.  This is a very simple network, so the static
route (with qualified next-hop-router) was the easiest compared to using
either RIP or OSPF.  Also as you suspected, my ISP's don't allow routing
protocols...for obvious reasons.

So the only way for XORP to detect that my ISP gateway is down is if the
network interface flags change right (i.e when unplugging the wire or
basically breaking the link)?  If that is the case, then I'll go with
the scripting method.

Thanks,
Tuan

-----Original Message-----
From: Pavlin Radoslavov [mailto:pavlin at icir.org] 
Sent: Monday, January 14, 2008 12:36 AM
To: Adam Greenhalgh
Cc: Tuan Hoang; xorp-users at xorp.org
Subject: Re: [Xorp-users] static qualified next-hop-router problem 

Adam Greenhalgh <a.greenhalgh at cs.ucl.ac.uk> wrote:

> Tuan,
> 
> You didn't say whether you were running any routing protocols.
> 
> Adam

My interpretation of Tuan's email is that the used protocol is "static
routes".

The obvious solution would be to use a dynamic protocol like RIP or
OSPF. Though, if your ISPs don't let you run any, then this is not an
option for you.

The StaticRoutes solution can't track the status of remote gateways on
its own; this is why there are dynamic protocols.

One possible work-around hack is to use an external script that helps
StaticRoutes tracking the status of the gateways.

The script will run a periodic ping to the primary gateway. If the ping
fails, then the script will use xorpsh to reconfigure XORP by changing
the next-hop address to the secondary gateway.

Hope that helps,
Pavlin

> On 09/01/2008, Tuan Hoang <tuan.hoang at agilecommunications.com> wrote:
> >
> >
> >
> > Hi,
> >
> > I'm using a XORP 1.4 under CentOS 4.5.  I have a router connected to

> > two ISP's and want to detect when my primary gateway is down on eth1
(Note:
> > ethernet link is still up but gateway is unreachable) and then 
> > switch over my default route to my other ISP's gateway on eth2.
> >
> > I have the static route configured with the a simple next-hop-router

> > to eth1 with ISP1's GW and also a qualified next-hop-router to eth2
with ISP2's GW.
> > When I turn off my cable modem to ISP1, XORP does not change my 
> > default route's GW to ISP2's GW on eth2.  The only way I've gotten 
> > this to work is by removing the eth1 ethernet cable to cause the
interface flags to change.
> >
> > FWIW, I've made sure that the ARP cache is flushed for the ISP1 GW.
> >
> > Thanks,
> > Tuan
> >
> > P.S.  Please reply all since I am not subscribing to the list.
> > _______________________________________________
> > Xorp-users mailing list
> > Xorp-users at xorp.org
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> >
> >
> 
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