ip classless Command

In CISCO routers, the ip classless command has to be enabled when using classful Routing Protocols; and you need the router to use the default route when it receives a packet destined towards an unknown subnet of a network, whose some subnets are known to the router.

For example, consider a Router A, which knows the routes to subnets and and the default route is set. If this router receives a packet destined to an address in the subnet and the ip classless command is not enabled, the router then discards the packet without using the default route. This is because, classful routing protocols assume that if they know some of the subnets of a network, it should know all the existing subnets of that network!

Enabling ip classless tells the router that it should follow the best supernet route or the default route for unknown
subnets of known networks, and for unknown networks.

Tagged ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: