Ping network address

[spyoung]

Hi,

By successfully pinging a network address, what does it actually mean?

Let me explain my query:

I have a simple serial connection between two routers RTR1 and RTR2.

RTR1 has an fa0/0 interface.

Lets say RTR1 fa0/0 is in the network 192.168.150.0/24. I dont know its actual interface address for that segment.

If I can successfully ping 192.168.150.0 (the net address) from RTR2, can I

assume the interface fa0/0 on RTR1 is UP....?

Or does it just mean the logical address space of that network is up.?

Thanks alot

Simon

[dnagarajachary]

If it is a point to point link , yes, you can say the link is up and also get the ip address at the other end.

Here is the output which is did in test lab.

HUB#ping 172.16.10.0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.10.0, timeout is 2 seconds:

Reply to request 0 from 172.16.10.2, 1 ms

Reply to request 1 from 172.16.10.2, 1 ms

Reply to request 2 from 172.16.10.2, 1 ms

Reply to request 3 from 172.16.10.2, 1 ms

Reply to request 4 from 172.16.10.2, 1 ms

But if you are not using a point to point network, i.e, if the network resides on some other segment, then you wont get success response.

The output for this is

HUB#ping 3.3.3.0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 3.3.3.0, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

-Deepu

[olorunloba]

If the line protocol of the interface is up and it knows the route back also, I expect it to reply (and if there are no access list denying it). The diffrence in the replies is that, if it is a directly connected, broadcast network, you get replies from each device. If it is not direclty connected, then, you just get the !!! symbol showing you replies.

[dnagarajachary]

yes, you are right, if it is a directly connected, broadcast network, the replies are sent.

But when you are pinging a network address which is more than two hops away, if it doesnt fall in the same subnet, then you wont get !!! symbols. If it falls in the same subnet or network, then you would get !!!!! symbols, otherwise, it is only ....

-Deepu.

[spyoung]

Great thanks for the answers guys.

Just one small question, what do you mean by a "broadcast" network...?

do you mean a network where if broadcast address is pinged (i mean the last address in a range, but not a valid device address) it will produce an echo repsonse from all devices on that net..?

I thought it was good practice to somehow prevent this kind of repsonse by stopping the router fwding the broadcast to all devices on the net..is this true?

thanks

Simon

[dnagarajachary]

You can stop the router forwarding the broadcast by giving the command

"no ip directed-broadcast" under the interface mode.

-Deepu