On 6 Jan 2020, at 16:09, Giotsas, Vasileios <v.giotsas@lancaster.ac.uk> wrote:
I tried to map the organization names to ASNs using WHOIS but I couldn’t find a match for about 50% of the organizations involved in transfers. What is the rationale behind not listing the AS number?
Because it's not rational or meaningful to do that. There's no reason to assume that there's a static, unchanging binding between address space and an ASN. Whatever ASN is associated with some address block today (if there is one) might not be associated with that block tomorrow. Or an organisation might buy transit from two (or more) providers and have each of them use their ASNs when announcing routes for that organisation's address block(s). Also, the RIRs only issue an ASN when a network is multi-homed: ie connected to more than one external network. See RIPE 679. It's possible the recipients of some of the transfers you found might not have multi-homed networks. Which would mean there was no relevant ASN for these to include in the transfer database.
Is it because organizations without an ASN (e.g. enterprise networks) can obtain an address?
Organisations generally only need an ASN if they intend to do BGP and manage external routing by themselves. Sometimes an organisation will "outsource" routing and BGP operations to a third party -- for instance buying transit from an upstream provider -- and therefore won't really need their own ASN. [This is what your university does. Its address space seems to sit behind JANET's ASN and doesn't appear to have its own - just like most/all UK universities.] In other cases, an organisation could use globally unique IP addresses for their internal network. In that case, they'd have no reason to route these addresses on the public Internet => no need for an ASN.
Is there a suggested way of mapping the organizations to ASNs besides WHOIS lookup?
whois is never the answer. Avoid. Use ripestat. This will probably have answers for all/most of the research data you are looking for.