01 Apr

Why NIXI AS24029 appears to be transit ASN?

And my post on 1st April. Don’t take it as April fool post 😉


Multiple times NIXI’s AS24029 has been reported as acting like transit ASN for multiple networks. I have analysed it in past and this is very much because of route leaks by few specific networks. I have explained difference in peering Vs transit routes and their handling previously on my blog.

In short: A network is supposed to re-announce it’s peering and transit routes only to customer and not to any other peer or upstream. Whenever NIXI’s ASN appears in global routing table, its always the case where one or more networks are re-announcing routes learnt via NIXI to their upstream transits. 


Looking at Hurricane Electric’s bgp.he.net for NIXI’s AS24029, we get:



Now according to this – many ASNs are peers of NIXI and visible to HE. The problem with HE’s data is that it doesn’t shows who is downstream and who is upstream (but is pretty fast!). Looking at stat.ripe.net data for AS24029, we get:



This is very interesting data as left side are the ones which are actually announcing these routes to their upstreams. Finding  upstream is tricky since these are filtered out at global level are don’t stay in the global routing table. It would be overall hard to find ones whose path count is low but for ones with large path count, we can likely see those routes in RIPE RIS collected data. 

Using bgpdump on RIPE RIS data, I get:


Refinding more of AS path part, we get:

Here we get the culprit ASNs. 🙂

So why does this happens?

Mostly it happens due the way filters are controlled in routers. Most of networks open their filters with upstreams to announce their customer routes. Now if customer routes are received via NIXI, they are re-announced as well. So in many of these cases these networks have/had the origination ASN as customer. 

These are the prefixes which are causing this:


 So that’s all about NIXI route leaks. Wish NIXI becomes a International hub for traffic exchange between Europe/Middle East and East Asia and as per current policy it’s no where around promoting domestic traffic exchange let alone international one! 


Disclaimer: I work for an Indian ISP and all comments here are completely personal. In no way it reflects my employers view.