Tier-1

Understanding the game of bandwidth pricing

I thought about this long back - “Who pays to whom in case of internet bandwidth?” I have been working in this domain from sometime and so far I have learnt that it’s really complex. I will try to put a series of blog post to give some thoughts on this subject. Firstly we have to understand that when we talk about “bandwidth price” it’s often layer 3 bandwidth which you buy in form of capacity over ethernet GigE, Ten-GigE and so on (or STMs if you are in India). As we know from back school class in networking - layer 3 works over layer 2 and so to deliver “bandwidth” on layer 3, one needs layer 2 physical circuit. Price paid by companies on layer 2 Vs layer 3 varies significantly based on their location, type of business, their target goal etc. E.g a content heavy company like Google pays hell lot of money on layer 2 circuits while it is strongly believed among networking community that Google is a tier 1 network and hence a “transit free” zone and they do not pay any amount on layer 3. In general the trend is pretty much as big networks have larger network footprint and connected “PoPs” over layer 2 (leading to a higher layer 2 bill) while relatively lower layer 3 bill while small networks depend significantly just on transit bandwidth (in form of layer3) and have very low layer 2 footprint.  

Backend of Google's Public DNS

And finally academic session over. Done with all vivas and related stuff. Next will be exams likely in June. Time for me to get ready for travel. :)   Anyways an interesting topic for today’s post - Google Public DNS. Lot of us are familier with popular (and free) DNS resolvers 8.8.8.8 and 8.8.4.4. I have covered reason in previous posts on why it tends to fail with Content Delivery networks like Akamai which rely on anycasting at bottom DNS layer and simple unicasting on application servers. Anycasted DNS nodes point to application servers based on various factors like distance, load, cost etc out of interesting algorithms these CDN networks use for load & cost management.   Anyways today’s post focus is not CDN issues with these resolvers but Google Public DNS itself. Are these servers located in India and everywhere else where Google has PoPs?   Let’s do a simple trace to get forward path from Airtel to Google’s 8.8.8.8: