From: W. Alan Robertson (warobertson@earthlink.net)
Date: Fri Oct 03 2003 - 13:13:32 GMT-3
R4 has a routing table, even if it only consists of entries resultant from
connected interfaces.
So long as the ping requests appear to have originated from a source locally
attached to R4, it can respond to those requests as though they were local.
By NATting everything at R3, replies from R4 will be sent back to R3 on
their common segment. R3 will then translate and forward the ping replies
to their original sources wherever they may be.
R4 isn't aware of the ping source being non-local.
In the real world, you can use this method to communicate with a remote
device that has either a mis-configured, or missing default gateway. (Been
there, done that.)
----- Original Message -----
From: "Ozgur Guler (Garanti Teknoloji)" <OzgurG@garanti.com.tr>
To: "Cezar Fistik" <cfistik@moldovacc.md>
Cc: <ccielab@groupstudy.com>
Sent: Friday, October 03, 2003 12:01 PM
Subject: RE: Possible NAT?
> how should nat work if the problem is r4,
> not being able to route the packets back?
>
> Ozgur
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Cezar Fistik
> Sent: Friday, October 03, 2003 6:51 PM
> To: ccielab@groupstudy.com
> Subject: Re: Possible NAT?
>
>
> Hello Ray,
>
> Friday, October 3, 2003, 5:23:58 PM, you wrote:
>
> BR> R1----OSPF----R2----OSPF----R3----No routing protocol running----R4
>
> BR> Do not run a routing protocol between R3 and R4; however you
> BR> should be able to ping R4 from any other router on the network.
> BR> My thought was to redistribute the connected network between
> BR> R3 and R4 into ospf and then do a static nat between R3 and R4.
>
> NAT should work, you porbably missconfigured it.
>
> Here's another solution:
>
> The problem here is that packets arrive to R4, but R4 doesn't know
> where to send them, since no routing protocol is running and I assume
> static routes are not allowed as well.
>
> You could try to implement a route-map on R4 that will forward any
> locally originated ip packet to R3 and from there to the rest of the
> network.
>
> BTW, someone please tell me if a route map with a default next-hop is
> considered a static route or not? If yes then my solutin sucks.
>
> --
> Best regards,
> Cezar mailto:cfistik@moldovacc.md
>
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