[smokeping-users] Re: fping issue?

Dez Cadena dez at otenet.gr
Fri Jan 27 11:50:39 MET 2006

Kennedy Clark wrote:

>On 1/26/06, Dez Cadena <dez at otenet.gr> wrote:
>>Updating myself here...
>>I've realised that fping only succeeds if I set the packet size to
>>something really small (e.g. 20bytes)
>>whereas ping has no problem with the default packet size (56). The
>>mystery remains.
>Two things to try:
>1) If you have access to the 2600 router, telnet/SSH to it and do a "term
>mon" and a "debug ip icmp".  Might give some clues.  Could also do a "debug
>ip packet detail <acl_#>" for a slightly different view.  Should help
>indicate if: a) echo requests are reaching the router, and b) if it is
>2) Capture a few sample packets with both ping and fping using tcpdump.
>Assuming you are SSH'ed to to a UNIX box, you might try something like:
>    tcpdump -p -w <filename_here> not port 22
>Then do a ping each way and Ctrl+C to kill the capture.  You can then view
>the file with something like Ethereal.
Unfortunately, I had already tried both 1 and 2 already. From (1) I 
gathered that fping echo requests
are NOT reaching the router. (2) was inconclusive because I could not 
spot any significant differences between
fping and ping echo requests.

I've also found out that there's a few more devices that behave 
similarly. They all are cisco 26xx with the same IOS
release but so are many many other *responsive* targets.

thanks for the input

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