Problem with 2 routers and a host

Hulkamaniac

Im having a problem displaying the image.So here it is:
ROUTER A's interface is 192.168.3.254
connected to
ROUTER B's interface is 192.168.3.253
ROUTER B's second interface is 192.168.2.251 which is connected to host A 192.168.2.250
Router A is connected to Router B, and Router B is connected to Host A.

Im having a problem. Interface 3.254 cannot ping Host A, and Host A cannot ping interface 3.254. Im running RIP and interfaces 2.251 can ping 3.254 and vice versa, but host A can not be reached. All lines are up with the no shutdown. Subnet masks are 255.255.255.0 across the board.
ROUTER B
router rip
network 192.168.2.0
network 192.168.3.0

ROUTER A
router rip
network 192.168.3.0

note: if you right click the angelfire logo /properties/ and copy paste the URL to your browser, you can see the diagram.

Can someone help me please?

shadown7

Make sure the host has the right IP address and default gateway settings.

johnnynodough

What type of cable are you connecting to your PC.

Also you can elimate a PC problem by using an extended ping command.

Router#ping
Protocol [IP]
Target IP addresss : 192.168.3.254
not posting rest until,
Extended commands [no]: Y
Source address of Interface : 192.168.2.251
not posting rest.

Do that on router B. If it goes through then the probelm is the PC config or cable.

Hulkamaniac

What type of cable are you connecting to your PC.

Im using crossover cables from the PC to the router B and from router A to router B.

Thank you for the suggestion. I'll try it.

johnnynodough

so your good wity the cables then. Try that extended ping command, I think youll find that the config on the PC is bad. I dont even use host computers anymore to test connectivity, just extended ping commands from the questioned interfaces.

Hulkamaniac

I think youll find that the config on the PC is bad.

Yeah. I didnt define a default gateway on the PC. Could that be the problem? And I will try the extended ping as you said.

johnnynodough

Bingo, the PC doesnt know where to send packets for IP's not on its subnet, and when you send a PING from 3.254, they get to the host but cant get the echo back from the PC.

Hulkamaniac

so is the answer to define a default gateway? And if so, what should it be? Thanks.

johnnynodough

set the default gateway to the IP address of the routers interface that it is connected to. Every LAN that will communicate externaly beyond the LAN needs to have a router interface on that segment. When you have the default gateway defined, and you request to send data (ping) to an address that is not in its same subnet (the host will calculate its ip address against its mask to determine that) it will send the data to the router and say "here you go, I dont know how to get there so do it for me". If you dont have a gateway configured, the pc will perform the calculation and say "its not on my subnet, and there is no one I can send it to, so I will just not do anything, ill output a destination network unreachable". A packet wont even leave the NIC.

Hulkamaniac

Thanks alot. I'll give it a shot.

johnnynodough

Your very welcome

shadown7

Yep, just like I said. That default gateway can get you every time.

johnnynodough

Good call, thats why I dont even bother with using hosts anymore, I change the configs on my labs so often that I cant keep up. I just use extended pings.