IP CLASSLESS is a little hard to understand. Even Cisco is very vague on this. Once a TAC engineer just told me that the command just makes routing better. Here is what I believe happens.
If you don't have the "IP CLASSLESS" command defined in a Cisco router then the router will not forward any packets towards a default route for any subnets of a classfull network that the router thinks are local. For instance. Rtr A local net 10.1.0.0/24. 192.168.1.0 interconnects routers a and b RTR B (sends default network only to RTR A and RTR C) 192.168.2.0 interconnects routers b and C RTR C local net 10.2.0.0/24 Note how 10.0.0.0 is split by the 192.168.1.0 and 192.168.2.0 networks. In the above example if RTR A gets a packet destined for 10.2.0.1, but it does not have the "IP CLASSLESS" command defined then RTR A will drop the packets. If you include the IP CLASSLESS command then the packets will be forwarded to the default router b. I hope this helps Mike Paulson Network Architect Infrastructure Design Systems LLP Hunt Lee wrote: > Can anyone please explain to me what is "ip classless" used for? I looked > it up on the Caslow book, and it states that by enabling IP classless, it > allows one to override the contiguous subnet rule and allow the router to > look for the longest match beyond the listed subnets. > > But I still don't understand what it means? Can anyone give me some > examples? > > Thanks in advance. > > Best Regards, > Hunt Lee > IP Solution Analyst > Cable & Wireless [GroupStudy.com removed an attachment of type text/x-vcard which had a name of michael.paulson.vcf] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=30087&t=30056 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
