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I'm pretty new to networking and I've just got started into using cisco packet tracer (a network simulator program).

My topology is basically a router, two switches connected to this router and per switch there are two computers.

one switch is connected on fastethernet0/0 ( the other is connected on fastethernet0/1 (

Now if I use one of the computers on one switch to ping to one on the other switch it fails... however, computers on the same switch can ping each other and the router...

Like I said... I'm pretty new and I might be missing something here.

Can anyone help me figure this out?

Thanks in advance! Dempsey

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The IP addresses of the two computers, along with the netmasks will be helpful. The computer's default routes as well. Thanks... – Nevin Williams May 14 '13 at 19:22
You have to configure your computers with respective default gateway, which is router's IP address. For example, the PC connected to the switch which is on fa0/0 uses as – Ashtray Nov 26 '13 at 9:11

Just make sure both of your switch and router are in the same gateway. Either or

After changed to the same gateway, then it should work on the ping.

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Let me add to what #TonyTan says.

You need to assign the Gateway Address on all you PCs (from the IP Configuration tab) The gateway address of the devices in a network is usually the ip address of the L3 device (Router's Interface) it is connected to.

For Example:

On the network connected to FastEthernet0/0 ( ip , you need to assign IPs to the PCs here from the same network IP range, i:e; So, the IP Configuration on a PC here would look like :




While the IP Configuration on a PC on the network at Router interface FastEthernet0/1 would be like :




Heres what you'd wana know about a gateway address.

When the message (say Ping) needs to go on to another network (destination address is in another IP range), it need to exit the current network cuz obviously the destination address won't be found in the same network (same IP range).

So to get out of the current network, it has to be forwarded to the gateway, which is the router (L3 device), because it is the router that can redirect data between networks.

Thus Gateway address = IP of Router Interface (or L3 device) connected to network

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