From: G F Marsh (gfm@xxxxxxxxx)
Date: Tue Jan 16 2001 - 12:26:25 GMT-3
RIP and IGRP route based upon the first 3 bits of the first octet of the ip
address in binary and do not use a subnet mask to route packets. Class A =
010 (1-126 in decimal) Class B = 101 (128-191 in decimal) and Class C = 110
(192-223 in decimal).
As you know the default masks are A=255.0.0.0 B=255.255.0.0 C=255.255.255.0
Whereas OSPF, BGP, EIGRP, IS-IS and RIPv2 can use VLSM (variable length
subnet masks) thereby routing classlessly. These protocols use the mask
information to route the packets.
I don't know if this is what you wanted explained or whether I have
explained it well enough but it certainly has major implications on route
redistribution between classless and classful protocols.
Gary
----- Original Message -----
From: <ccie2b@usa.net>
To: <ccielab@groupstudy.com>
Sent: Tuesday, January 16, 2001 2:01 PM
Subject: Re[2]: aggregate addresses and redistribution
> Familiar with most issues, but this one keeps eluding me for some
> reason...never had anyone explain it...and yes, 2 weeks and
> closing...need help, not criticism...
>
> Devinator
>
>
>
> > You are walking into the lab in 2.5 weeks and you are unfamiliar with
> > classful versus classless issues?
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> > ccie2b@usa.net
> > Sent: Monday, January 15, 2001 7:37 PM
> > To: ccielab@groupstudy.com
> > Subject: aggregate addresses and redistribution
>
> > I keep hearing about having OSPF and igrp (or rip) having to have
> > matching masks or something. I don't understand what this is, applies
> > to, etc. Can someone enlighten me in layman's terms as to this
> > mask-matching thing?
>
> > Thanks ALOT,
>
> > Devinator
> > ccie2b@usa.net
>
>
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