From: libone mhlanga (libone@lycos.com)
Date: Fri Mar 20 2009 - 06:56:03 ART
I think these are good questions ...I will ans the 1st part according to
my understanding and research the rest ...Doyle " Routing TCP/IP" Volume
I has a section on classful behaviour :-
"The way I understand it, is without the ip classless command, a router
would check the routing table for a known major class of the destination,
if no subnets are found within that major class, the packet is dropped.
However if the packet is for a destination, totally unknown to the
router,
it will use the default route?"
I would say no without the ip classless cmd the router will never use its
default route !
<---------[ Received Mail Content ]----------
Subject : Classful Vs. classless behavior [7:134774]
Date : Fri, 20 Mar 2009 05:06:36 -0400
From : "k.jungle@gmail.com" <k.jungle@gmail.com>
To : cisco@groupstudy.com
Hi All,
My first post here, so I hope im being specific enough :)
I am studying some classles versus classful behavior, and a couple of
things came up.
First of, the "ip classless" command seems to only affect the routing
process, and has nothing to do with the routing protocol in place, is
that
correct?
The way I understand it, is without the ip classless command, a router
would check the routing table for a known major class of the destination,
if no subnets are found within that major class, the packet is dropped.
However if the packet is for a destination, totally unknown to the
router,
it will use the default route?
With the ip classless command however, you could have a major network
matching the packets destination address, but if no more specific route
is
known, it would still use the default route?
The final thing that wont quite stick, is with a classful routing
protocol
(RIPv1 for instance), if it receives a route update, with a major network
different from the receiving interface, it will assume its classful, and
use the classful "part" of that route.. For example. 172.16.2.0 is
received
on an interface 10.10.10.1. It will install the route 172.16.0.0 into the
routing table? And the VERY final (i promise :) ) is if it receives a
subnet of a major net, on an interface with the same major net, it will
use
the interface's mask to install into the routing table. For example.
192.168.2.16 is received on an interface with an ip of 192.168.2.1/28, it
will install that route as 192.168.2.16/28 as well?
Sorry if its confusing, and please let me know if i can elaborate in any
way!
Thanks in advance!
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