Today I noticed some traffic on my blog from a link from Broadband forum. Here’s what poster wrote: I made a thread a few days ago complaining about BSNL’s horrible routing. Well it looks like it has been fixed. I thank all the guys who made efforts to bring this to BSNL’s notice. Especially Anurag Bhatia who highlighted the issue with much detail on his blog Softlayer connectivity problem and possible fix.
It’s late night here in India. I am having final 8th semester exams and as usual really bored! Though this time we have interesting subjects but still syllabus is pretty boring spreading across multiple books, notes and pdf’s. Anyways I will be out of college after June which sounds good. Tonight, I found a routing glitch. Yes a routing glitch!! :) These issues somehow keep my life in orbit and give a good understanding on how routing works over the Internet.
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 184.108.40.206 and 220.127.116.11. 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.
Just was looking at routing tables of BSNL. They have a significant address space in /10 - 18.104.22.168/10. Overall this /10 address space is divided into /18 and /20 subnets. Let’s pick two of such subnets and observe routing tables from route-views: 22.214.171.124/18 126.96.36.199/20 Routing table for 188.8.131.52/18: * 184.108.40.206/18 220.127.116.11 0 3333 3356 6453 4755 9829 9829 9829 i * 18.104.22.168 0 3277 3216 6453 4755 9829 9829 9829 i * 194.