Classfull Routing with RIPv1 or IGRP & the Network Command

[ElijahBaley]

Hi

I have a bit of trouble with the 'network' command. As I understand it RIP v1 and IGRP can only route classfull networks meaning that they can only distinguish networks based on the default subnet mask values for class a,b & c networks.

so the first example below makes perfect sense as the advertised networks are '1' and'2' (199.1.1.0/24 & 199.1.2.0/24)

but I get confused when I see example like the second one, from what I can tell the router will advertise network 10.0.0.0/8 and the two address on each of the interfaces will be interpreted as two different nodes on the same network (network 10.0.0.0/8 - nodes 10.1.2.3 & 10.1.3.3

Where am I going wrong?

How can you have subnet addresses on these interfaces if the routing protocol can't handle them?

Please help!!!

Thanks
---------------------------------------------------------
int s0
ip address 199.1.1.1 255.255.255.0
int s1
ip address 199.1.2.1 255.255.255.0

router rip
network 199.1.1.0
network 199.1.2.0
---------------------------------------------------------
Int s0
ip address 10.1.2.3 255.255.255.0
int s1
ip address 10.1.3.3 255.255.255.0

router rip
network 10.0.0.0
---------------------------------------------------------

 

[dogbert2]

Simple,

Issue the 'show ip route' command in priv. mode to see
exactly what is in your routing table (what it knows about, and what it advertises to neighbor routers). This will show you what (if any) subnet mask information is being
transmitted with routing updates.

Another method would be to use a network sniffer and watch the routing updates go across the wire, and break them down by packet/frame, etc.

 

[ccprep]

The rule with a classful routing protocol is that the protocol will advertise subnets on interfaces belonging to the corresponding class of network.

For example, RIP will advertise the subnets 10.1.1.0 and 10.1.2.0 out all interfaces that have an address in the 10.0.0.0 address space.

Lou Rossi
CCPrep.com

 

[ElijahBaley]

Thanks for your comments,

I am sorry that I am a bit slow with this, but could you illustrate how the above examples compare with CIDR

EB