[109672] in North American Network Operators' Group
Re: Recommendation of Tools
daemon@ATHENA.MIT.EDU (Pekka Savola)
Thu Dec 4 08:06:03 2008
Date: Thu, 4 Dec 2008 15:05:50 +0200 (EET)
From: Pekka Savola <pekkas@netcore.fi>
To: =?ISO-8859-15?Q?Anders_Lindb=E4ck?= <list-only@dnz.se>
In-Reply-To: <943AC9CD-ABC3-406D-9799-E1B3664A3123@dnz.se>
Cc: nanog@nanog.org
Errors-To: nanog-bounces@nanog.org
This message is in MIME format. The first part should be readable text,
while the remaining parts are likely unreadable without MIME-aware tools.
--1589707168-1214896362-1228395950=:8919
Content-Type: TEXT/PLAIN; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 8BIT
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
--1589707168-1214896362-1228395950=:8919--
