Re: Mapping IP -> ASN

[Jim Van Baalen <vansax () atmnet net>]

> Lyndon Nerenberg wrote :
> ->   Is there a tool available that will take an IP address and return the 
> ->   ASN attached to that network? I've been in situations before where this 
> ->   information would be useful, but not having access to the BGP routing 
> ->   information I'm not sure how to do this? (I've looked around some 
> ->   "likely" web sites - such as Merit - but haven't found anything.)
> ->   
> ->   The pressing need is for the ASN associated with 198.161.92.0. This 
> ->   network is connected to I*star, but I can't tell which of I*star's 
> ->   three ASNs it's homed on. (And they aren't being responsive to queries.)

Versions of traceroute that support the "A" option are also a nice quick
way to get this info. Cisco routers do this by default.

ex.
sd-gw-1>traceroute cisco.com
Translating "cisco.com"...domain server (207.67.247.4) [OK]

Type escape sequence to abort.
Tracing the route to cisco.com (198.92.30.31)

  1 agis-atmnet.losangeles.agis.net (206.62.12.49) [AS 4200] 4 msec 4 msec 4 msec
  2 a5-0.1009.santaclara3.agis.net (205.254.168.249) [AS 4200] 16 msec 12 msec 12 msec
  3 mae-w.bbnplanet.net (198.32.136.14) 36 msec 32 msec 52 msec
  4 paloalto-br2.bbnplanet.net (4.0.1.13) [AS 1] 32 msec 164 msec 240 msec
  5 su-pr2.bbnplanet.net (131.119.0.218) [AS 200] 232 msec 36 msec 32 msec
  6 cisco.bbnplanet.net (131.119.26.10) [AS 200] 36 msec 36 msec 36 msec
  7 sj-wall-2.cisco.com (192.31.7.34) [AS 109] 36 msec 64 msec 36 msec
  8 sj-eng-corp2.cisco.com (198.92.1.130) [AS 109] 40 msec 40 msec 44 msec
  9 cisco.com (198.92.30.31) [AS 109] 36 msec 32 msec 33 msec 
sd-gw-1>

Jim
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