comp.os.linux.networking

In article , Geoff Lane
datemasde.t1m@gishpuppy.com says...
> I was under the impression that Ping and Tracert were similar utilities
> with tracert giving a wee bit more information about the connection.
>
> Why is it then, if I ping bbc.co.uk I get response times of around 30ms
> whereas if I tracert the same address it appears to take much longer.
>
Ping sends a ICMP packet to the server, which sends an acknowledgement
back (if it's running the ping service). Traceroute sends an ICMP
packet which has expired, which causes an error at the first router it
reaches - the router returns an error message which includes the
router's details that traceroute then displays. It then sends another
packet that hasn't quite expired, which will pass through the first
router but be caught by the next, and so on down the line. Routers are
optimised to pass packets very quickly, but error messages are a lower
priority so it will take longer for the router to return an error
message than it will for it to forward a good packet. The final hop of
the traceroute to the destination address also prompts an error response
(port unreachable), while ping servers do nothing but reply to ping
requests all day, so they're pretty good at what they do. :-)

Why do you keep crossposting to uk.comp.home-networking but quietly
setting followup to comp.os.linux.networking? I don't read that group.