Wrong? Me? Golly, I had trouble sleeping last night after reading that...!
; )
Your definition is almost word-for-word what is reflected in the CCO docs or
a textbook. The docs say what the entry does, but say little about how or
why, which was the essence of the original question. So, I wanted to frame
the overall concept in a way that is more easily understood.
I take for granted that most folks have gone to CCO to look at the
definition there, and did not feel it was neccesary to copy and paste that.
What we REALLY wanted to do is look under the hood and achieve an
understanding as to WHY, and how it might impact our network design
decisions. (Like, don't use RIP or IGRP...? :) )
Just for grins, the definition I prefer, from Jeff Doyle's book, pp765 "IP
Classless : Enables classless route lookups so that the router can forward
packets to unknown subnets of directly connected networks."
Beyond this, I agree that your statment is correct, but somewhat incomplete
and therefore misleading. The meat of the issue IMO is the paradigm shift
between Classful and Classless address space, routing and the ramifications
when it comes to early distance-vector routing protocols.
Have a good one,
Casey
>From: "whatshakin" <[EMAIL PROTECTED]>
>Reply-To: "whatshakin" <[EMAIL PROTECTED]>
>To: <[EMAIL PROTECTED]>
>Subject: Re: ip classless ?
>Date: Wed, 23 Aug 2000 00:27:27 -0700
>
>This is wrong amigo.
>
>The 'ip classless' command is used when configuring default routes. It is
>used because when you create a default route on a router it gets advertised
>as 0.0.0.0 in addition to the default network. When a router recieves the
>advertised default route it will forward packets to a destination which
>does
>not appear in its routing table. Specifically you need to use the 'ip
>classless' command when using IGRP and EIGRP because they only advertise
>the
>network you configured on them. If you do not use this command to enable
>the default path to be used for non-connected subnets of the same major
>classful network, the packets will be dropped at the router.
>
>
>----- Original Message -----
>From: Casey Fahey <[EMAIL PROTECTED]>
>To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
>Sent: Tuesday, August 22, 2000 8:48 PM
>Subject: Re: ip classless ?
>
>
> > Ah yes, classful addressing. Blast from the past...
> >
> > I am assuming you are aware of the classes of IP addresses, and how a
> > class A address has a first octet of 1-127, etc..
> >
> > Well, what IP Classless means is that the router *does not* assume that
>an
> > IP address with a first octet of 1-126 is a /8 address, 128-191 a /16
> > address, 192-223 a /24 address and so forth.
> >
> > Sound a bit archaic? Hmm... So are IGRP and RIP. ; )
> >
> > Your question is kind of tough to answer directly, since you do not need
>to
> > use IP Classless unless you need to break, say a 10.x.x.x network into
>/24
> > subnets. If you don't include IP Classless, the router will assume the
>mask
> > is instead /8 and things will get weird...
> >
> > HTH,
> >
> > Casey
> >
> > >From: "Yee, Jason" <[EMAIL PROTECTED]>
> > >Reply-To: "Yee, Jason" <[EMAIL PROTECTED]>
> > >To: "'[EMAIL PROTECTED]'" <[EMAIL PROTECTED]>
> > >Subject: ip classless ?
> > >Date: Tue, 22 Aug 2000 22:07:51 -0500
> > >
> > >hi ,
> > >
> > >Anyone knows why when we use RIP or IGRP routing protocols and we have
>a
> > >default network command entered , we need to include ip classless?
> > >
> > >Any form of input will be greatly appreciated
> > >
> > >
> > >thanks
> > >
> > >
> > >Jason
> > >
> > >___________________________________
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