Re: a routing question from Joe Astorino on 2009-04-22 (Ccielab archives 04/2009)

From: Joe Astorino <joe_astorino_at_comcast.net>
Date: Wed, 22 Apr 2009 03:26:43 +0000 (UTC)

Well, once your DSL comes back up, your SLA will come back up, which will trigger your static default route to be entered back into your routing table....and that will have a lower AD than the one learned from router B so you will be all set. It's completely dynamic.

"He not busy being born is busy dying" -- Dylan

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----- Original Message -----
From: "Jafar T" <jafar_at_paris.com>
To: "Joe Astorino" <joe_astorino_at_comcast.net>
Cc: ccielab_at_groupstudy.com, "Bryan Bartik" <bbartik_at_ipexpert.com>, "Jafar T" <jafar_at_paris.com>
Sent: Tuesday, April 21, 2009 11:23:40 PM GMT -05:00 US/Canada Eastern
Subject: Re: a routing question

where to find a good sample for this config, and would this work, even the ip address is now rechable thru router B ?
how to fall back from it once dsl link is up

thx

----- Original Message -----
From: "Joe Astorino"
To: "Joe Astorino"
Cc: ccielab_at_groupstudy.com, "Bryan Bartik" , "Jafar T"
Subject: Re: a routing question
Date: Wed, 22 Apr 2009 03:06:30 +0000 (UTC)

*edit* I meant the default route coming from router B would have a
HIGHER AD , and thus be less preferable.

"He not busy being born is busy dying" -- Dylan

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----- Original Message -----
From: "Joe Astorino"
To: "Jafar T"
Cc: ccielab_at_groupstudy.com, "Bryan Bartik"
Sent: Tuesday, April 21, 2009 11:02:14 PM GMT -05:00 US/Canada Eastern
Subject: Re: a routing question

I did something similar to this before. Building on what Bryan
said, setup ip sla to do something like ping the default gateway
your DSL ISP gives you. At the same time, have router B advertise a
default route to router A. So, router A should have a static
default route tied to the SLA pointing to your DSL, and a default
route with a lower AD advertised from router B. If the SLA ping
fails, your static route goes away and the one being advertised
from router B kicks in.

"He not busy being born is busy dying" -- Dylan

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----- Original Message -----
From: "Jafar T"
To: "Bryan Bartik"
Cc: ccielab_at_groupstudy.com
Sent: Tuesday, April 21, 2009 10:49:44 PM GMT -05:00 US/Canada Eastern
Subject: Re: a routing question

thanks for the idea,
but will not work, i always want A to use that static to firewall, i just
want A to fail over if the dsl on the far far side of that fireall drops,
in other words, if the dsl drops, A switch to B
how can i do this tweak, without changing the FW config ?

thanks

----- Original Message -----
From: "Bryan Bartik"
To: "Jafar T"
Cc: ccielab_at_groupstudy.com
Subject: Re: a routing question
Date: Tue, 21 Apr 2009 20:29:42 -0600

It sounds like you need Router A to recognize when it should no
longer use
it's static default route, remove it, and then use the route towards
B. You
can create an SLA Tracker and tie it to the route. One thing you
would watch
out for is that whatever you track through the firewall is not
reachable
through Router B, otherwise the tracker would pass and the route
would come
up again. Although, maybe you could tweak the tracker to
differentiate...Any
other ideas?

Bryan Bartik
CCIE #23707, CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com

On Tue, Apr 21, 2009 at 8:02 PM, Jafar T wrote:

> hi team, i have a scenario, isp.......routerB......mpls/BGP.......router
A.....firewall.....dsl...isp
>
> routeb, needs to act as a failover for A internet traffic router
> A, only has a static route to Firewall interface, routerA, will
> never detect the the dsl link down, since it is on
another
> subnet so no matter what router B advertise, floting
> static..default originate....etc it willl be no good for A, it
> can see that in the table, looks
good, but
> will never be activated as a another default route, since A always
will
> see the static route to firewall, and it looks fine as far as the
router
> a can tell, how can you change that, without enable a routing
> protocol on the firewall, in another words,
without
> doing any changes on the firewall ? cheers JT -- It's News. It's
> Reviews. It's Interviews. It's Free. What Are You
Waiting
> For? www.movieline.com Blogs and organic groups at http://www.ccie.net
Received on Wed Apr 22 2009 - 03:26:43 ART

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