pinging from a router
Hardware, Network Interface Cards, Network Management Systems, Network testing, Networking, Networking Equipment, Routers, Security
hi all,
can you tell me what is the difference between pinging from a router and from a terminal.i have a cisco router.when i ping a remote router from my router it doesnot but when i ping the same remote router with the terminal attached to my router it pings.also sometimes when i ping from router it gives output as :_ _ _ U _.what does this U mean?
thanks for any help.....
Software/Hardware used:
Software/Hardware used:
ASKED:
May 19, 2005 3:06 AM
UPDATED:
May 19, 2005 11:34 AM
Answer Wiki:
Hi
"U" refers to an Unreacheable ICMP echo-reply. It can be either host unreacheable, or destination network Unreachable or an Admin Deny reply (access-list block).
What are you referring to as the "terminal"? A TServer or a host(PC)?
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hi
thanks. i mean by a terminal , a host pc.
Ok. It looks to be an access-list blockage. If you can try and do an extended ping to the remote router with the source address as the address of the Interface to which the PC is sitting behind, you should get echo-replies back.
You can find from the trace-path where the access-list is configured and enable icmp for the required source address ranges if required.
not sure of your setup , but lets make sure that we are pinging ip address not a host name that the router has no dns knowledge about!
eg ping bob
how is it translating bob to its ip address ?
hi thanks,
but can you tell me what basically is the difference between pinging from router and from a pc?
The difference would seem to be (based on previous comments) the source IP address of the device doing the ping (echo request).
If you are connected to the router by serial console cable vs. telnet, there may be a difference in the source IP address that the router uses – I do NOT know this for a fact, but based on previous dialog it seems likely.
As a previous poster pointed out, if you just enter the “ping” command by itself, the router will prompt you for the other values so that you can specify any source address that the router has on any of its interfaces.
Bob
Whether you ae logged in using the console port or using telnet or SSH there should be no difference in terms of pings.
You might want to try telling the router to ping from specific interfaces. Is the other router on the same logical wire as your router? You should be able to ping your workstation from the router since you can connect with telnet. Can you ping your router from the other router? If you have access lists they can really mess up diagnostics. Make sure you know precisely what they do.
I would be inclined to start by checking connectivity to a local system and work my way out to the other router. See where the failure begins. Another option is to try trace route.
rt