Networking

Sleepless night. Reading more about Quagga and it’s options.

In meanwhile a quick 5min script to enable domain to BGP/IP/ASN mapping. This script is using basic dig command (for finding IP address) and Team Cymru whois service for IP to ASN/block mapping.

#!/bin/bash  
\# Script for domain name to IP/ASN/BGP block mapping  
hostname=v4.whois.cymru.com  
IP=$(dig $1 a +short)  
whois -h $hostname " -c -p $IP"

Yeah just 3 line script! Less code = more power! 

It has been an interesting week at village - dry weather, (ultra) dry classes, (boring) external seminars and more of depressing environment but one can always find some hope out of such depressing environment. Overall life here is colourful but one just needs to lookout for colours. :)   One interesting case to report today - F root server has quite bad connectivity in India. Last week a friend asked me for traceroutes to all root servers and here’s what I saw when I did traceroute for F root from BSNL connection:

It has been super boring evening considering my sessional tests tomorrow. Test time is dull as always. I have been precisely measnuring latency on BSNL link from BSNL Haryana to Singapore based servers. The fluctuation in latency is pretty much common now. Someones we get 120ms latency to Singapore (an expected number based on distance) while other time it goes off as high as 310ms. Latency with openDNS nodes in Singapore makes it pretty much poor to use openDNS here.   Based on my collected data and BGPlay’s routing records, here’s what’s happening. My IP is coming /20 BGP annoucement from BSNL Autonomous System 9829 - 117.207.48.0/20. Looking at BGP table records for that block from BGPlay’s routing data archive source.

Subnetting IPv6 sounds very complex but to be true - it is very easy! All you need to do is to understand basics of IPv6 addressesing - how an address is formed and how to efficiently use CIDR notation.   Firstly how an IPv6 address looks like? (good to clear fundamentals first!) An IPv6 address has 8 sections seprated by coloums and each sections has carries 4 hexadecimal digits. So an IPv6 address is something like: xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx - Each x can have a hexa decimal value i.e from 0 to 9 and a to f. Thus 16 possible values for each x. Since each each x is stored in binary i.e 0 or 1 (that is 2 possible value) - number of bits per section turns out to be 2x2x2x2 = 16bits. Thus we have now each section with 16 bits per section and 8 sections in total. This turns out to be 16 + 16 + 16 + 16 + 16 + 16 + 16 + 16 bits = 128bit. This is why an IPv6 address has 128bits. This means total possible addresses in IPv6 space is 2^128 = 340 282 366 920 938 463 463 374 607 431 768 211 456 addresses. Next, an important point to remember here is  - in IPv6 address clients are mostly based on /64 subnet which means first 64 bits go to network part while next 64 bits go to the host part i.e usage IPv6 addresses which are allocated to end machines.  

In last few days, I have been pushing discussion on APNIC & NANOG mailing lists about poor DNS infrastructure in India.

Thought to put a quick blog post on the issue.

So what’s exactly wrong?

To understand what’s wrong, let’s understand how DNS works at core level. DNS relies on a hierarchy model with . (dot) on top which is Root and TLD i.e Top Level Domains below Root, which further  follow 2nd level domains which are popularly domain names we use. So e.g mail.google.com is actually like