Mapping IP -> ASN

> 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 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.

Only when that router is running full tables.

When traceroute is run from routers that aren't running BGP, you
just get hostnames/times.

I'd suspect that the only way to get traceroute with ASN's is when the
machine you're coming from (cisco routers, for example) know the tables.

There is a "public" cisco at - telnet there and
traceroute out :slight_smile: