Recommendation of Tools
pekkas at netcore.fi
Thu Dec 4 07:05:50 CST 2008
On Wed, 3 Dec 2008, Anders Lindbäck wrote:
> Mtr is even less usefull then that, in its default mode it does a traceroute
> and then proceeds to ICMP Ping flood each IP in the list generated by the
> traceroute, the result is usually completly useless on WAN topologies due to
> asym-routing, ICMP node protections by carriers and punting etc..
No, it doesn't try pinging the routers in the middle, at least not
anymore (I just re-checked with 0.71 and 0.75). I vaguely recall
behaviour like that in the past, however, so it's possible that long
time ago mtr did behave that way.
> And using UDP will not really provide better results due to the same thing,
> and IIRC Cisco from 12.0 has a standard setting of no more then 1 ICMP
> Unreach per 500ms..
This is true and the point I was getting at, though I believe the
bucket is much larger in any recent software release (also in 12.0
series). Actually, 5 years ago, you could see spot Cisco routers in
"traceroute6" because they dropped the rate-limiter didn't respond to
the middle packet and it resulted in a star. The rate-limiter has
long since been fixed to be more lenient.
Pekka Savola "You each name yourselves king, yet the
Netcore Oy kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
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