From: Jeremy Thompson (myriad@xxxxxxxxxxxxxx)
Date: Thu Jul 15 1999 - 15:33:56 GMT-3
Errol -
There is no way around this. Classful protocols will always advertise only the
classful network to a different major network. When using classful protocols al
l
subnets must be contiguous for a given network. Since they have no space in the
packet for the subnet mask, there is no way the receiving router could ever
figure out any number of network/host bits other than that dictated by classful
addressing rules, unless it has first-hand knowledge of a subnet mask for that
major network.
Jeremy
>
>
> -----Original Message-----
> From: Robichaux, Errol J (CAP, ITS, US) [SMTP:Errol.Robichaux@gecits.ge.com]
> Sent: Thursday, July 15, 1999 9:35 AM
> To: 'ccielab@groupstudy.com'
> Subject: VLSM - FLSM Problem
>
> I am experiencing minimal luck in my home lab with the following scenario:
>
> On edge-routers R1 and R4 I have networks of 150.100.1.0/24 and
> 150.100.2.0/24 respectively. The first edge-router is running IGRP and the
> second edge-router is running RIP. OSPF and EIGRP lie in the middle. The
> routing protocol redistribution would be as follows if laid out:
>
> IGRP - OSPF - EIGRP - RIP
>
> R1 runs only IGRP. R3 runs IGRP and OSPF, therefore handling
> redistribution. R5 runs OSPF and EIGRP, therefore handling redistribution.
> R4 runs RIP and EIGRP, therefore handling redistribution.
>
> The problem that I am experiencing is this. Since both routing protocols at
> the edges do not support VLSM, they are advertising 150.100.0.0/16.
> Therefore, the routers in the middle only see one route.
>
> Thanks in advance.
>
> Errol
>
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