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ping reply issue.

Can I ping to cisco device using network address?

Is it working?.

Let's see below.

interface fastethernet 3/3

ip address

no shutdown

I try to ping in my pc

c:\ping address for host ip

but I received different ip address(it's specific interface ip address in cisco router)

what I want to know about this situation is that network address can responce icmp request? or disgard?

if I received a reply, why it's ip address is other ip addresds?


Re: ping reply issue.

There is a good reason why you are seeing what you are. When you ping a network address, the router will convert the destination address to be (the local broadcast). It does that even though you entered a specific network address. The reasoning behind this is that you are attempting to ping the whole network and the best way to do that is to send a local broadcast. Now, every device on that LAN segment will receive the ping addressed to and respond to it. That is why you receive a reply from a different address to what you actually pinged. If you had more devices on the LAN, you would receive replies from all of them.

Hope that helps - pls rate the post if it does.


Hall of Fame Super Gold

Re: ping reply issue.

My experience is that this explanation of the router forwarding the ping to the network address as a local broadcast is correct if the router is configured with ip directed-braodcast. If the router is configured with no ip directed-broadcast then the router will not forward the ping as a local broadcast. In either case I have experienced that the router will generate a response to the ping request.

ip directed-broadcast used to be enabled by default. Then Cisco changed the default and now the default is to disable directed-broadcast. The reason for the change is that directed-broadcast is used by some denial of service attacks.




Re: ping reply issue.

Just a clarification to Rick's post. The 'ip directed-broadcast' capability only comes into play when the directed broadcast originates on a router other than the one that is directly connected to the destination network. For the router that *is* connected to the destination network, the 'ip directed-broadcast' command has no effect. Therefore, if you ping or from the router to which the network is connected, it will exploded into a local broadcast, regardless of how you have configured the 'ip directed-broadcast' command.


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