Networking

Just now completed IPv6 certification with Hurricane Electric. It was very much fun!

Starting was pretty much simple and basic, followed by email server running on v6 - which also I was doing already. I was stuck at most unexpected part - when I had to setup IPv6 based DNS servers. My first reaction was - that’s so simple….later on realized that system was just not accepting my entry and kept on giving error with AAAA records. Then suddenly I realized that I missed creating AAAA at DNS servers, but created only glue records which was causing issue. Created AAAA and that also went smoothly + glue helped me in final test too.

Hello everyone!

Seems like Tata Communications routing table is changed (call it fixed) to route traffic for openDNS to Singapore. It’s not going to London anymore and I see very good latency from BSNL too (which uses Tata Comm for most of it’s International traffic).

Here’s latest routing from BSNL to openDNS: 

HOST: laptop                                                                 Loss%   Snt   Last   Avg  Best  Wrst StDev

  1. router2                                                                        0.0%    50    2.0   1.7   1.5   2.2   0.2

  2. 117.207.48.1                                                             2.0%    50   25.4  26.2  24.5  36.1   1.6

  3. 218.248.173.38                                                        0.0%    50   26.1  31.2  25.0 125.5  17.8

  4. 121.244.68.114.static-lvsb.vsnl.net.in               2.0%    50   70.1  72.2  69.4  97.8   6.0

  5. 172.31.61.210                                                            0.0%    50   92.9  94.8  92.9 109.0   2.2

  6. ix-4-2.tcore1.CXR-Chennai.as6453.net            0.0%    50   94.3  98.4  93.1 154.6  12.6

  7. if-5-2.tcore1.SVW-Singapore.as6453.net          0.0%    50  127.2 130.6 125.8 165.5   8.5

  8. if-2-2.tcore2.SVW-Singapore.as6453.net         0.0%    50  126.8 128.6 124.4 178.2   8.3

  9. Vlan1807.icore1.SVQ-Singapore.as6453.net   2.0%    50  135.4 132.3 126.1 140.4   4.4

 10. 203.208.186.101                                                      0.0%    50  202.4 163.6 156.9 256.5  17.5

 11. 203.208.153.110                                                       0.0%    50  159.1 166.8 157.0 272.4  23.6

 12. 203.208.190.166                                                      2.0%    50  160.3 160.6 158.6 191.9   4.6

 13. resolver1.opendns.com                                           2.0%    50  159.0 158.3 156.9 162.4   1.0

Overall I am getting latency from 160ms which seems OK considering 25-30ms latency for DSL, adding 60-90ms for route till South India followed by 30-40ms latency between Chennai and Singapore and eventually destination openDNS node on ASN 36692. 

Yesterday I had a very interesting discussion with our senior administrator.

I was configuring reverse DNS records for our /24 block and I decided to use format - IP.static.domain.com thus if for IP 1.2.3.4, I pointed reverse DNS (PTR) to 1.2.3.4.static.domain.com

When I got chance to show my work to my senior administrator, he said - It’s wrong to use 1.2.3.4.static.domain.com in a hostname. Too many dots will make DNS resolution very slow (forward - reverse - again forward). And I should have used 1-2-3-4.static.domain.com

And here we get latest EIG cable i.e Euro India Gateway cable in action. Although cable was up few months back, but it’s now we are getting some changes in routing table up. (Probably earlier was test mode?).

Here’s a map of EIG cable.

This was very interesting project because of few reasons - firstly it is one (of few) cable consortium’s where India’s biggest State owned telco BSNL (also known as NIB - National Internet Backbone). Apart from that, it is one of direct link between India and UK. Earlier main route was from Mumbai to France (VSNL-Tata route) and next domestic Europeon bones Lamdanet, Telia, Level3 etc used to carry data further.

I can see heavy confusion on what is 4G? So thought to make a blog post about it.

Some people even feel like….

:) Let’s try to understand from basic definition about 4G.

As per ITU - 4G refers to wireless technologies which gives as fast as 1Gbps speeds when one is stationary, while 100Mbps speeds when one is on move. That’s it. Full stop.

1Gbps!!! Really?

Well, that’s “just in defination”. In real - there is no technology which is real 4G.

Which DNS resolver is better - ISP’s (default) DNS resolver, or Google Public DNS or the pioneer of DNS openDNS or even a local DNS server?

Let’s try to find out! I am sitting on a BSNL data link, and I will try to perform few tests to find that out: Available DNS resolvers to me:

1. BSNL DNS resolvers - 218.248.255.194 & 218.248.255.196
2. Google Public DNS - 8.8.8.8 & 8.8.4.4
3. OpenDNS - 208.67.222.222 & 208.67.220.220
4. Local DNS Server - BIND running on localhost - 127.0.0.1

Observing ping time:

BSNL DNS resolver:

--- 218.248.255.194 ping statistics ---

5 packets transmitted, 4 received, 20% packet loss, time 4001ms

rtt min/avg/max/mdev = 26.978/27.754/29.122/0.897 ms

--- 218.248.255.194 ping statistics ---
5 packets transmitted, 4 received, 20% packet loss, time 4001ms
rtt min/avg/max/mdev = 26.978/**27.754**/29.122/0.897 ms

Google Public DNS:

--- 8.8.8.8 ping statistics --- 5 packets transmitted, 
5 received, 0% packet loss, 
time 4001ms rtt min/avg/max/mdev = 121.147/121.878/122.951/0.783 ms

OpenDNS:

--- 208.67.222.222 ping statistics ---

5 packets transmitted, 5 received, 0% packet loss, time 4005ms

rtt min/avg/max/mdev = 217.678/**219.528**/222.034/1.717 ms

Next, localhost? :)

So, finally 3G is set to launch in India from Private operators. One of my friend came to me and asked:

“So what should we really expect from 3G? End of wired broadband?”

Very nice one!

Short answer - NO, NO yet!

It’s quite strange to see, how users are taking 3G. Actually it has been largely “overestimated” technology, specially from Indian media. Let’s first try to understand - What exactly is 3G? Without going into geeky definitions - 3G is simply upgrade from 2G. It uses higher frequency, and thus has more spectrum available for more bandwidth. That’s all. One important thing we need to understand is - 3G is more or less just a last mile technology i.e it connects telecom network’s exchange to consumer’s device. Mostly 3G, 2G, landline network, and broadband network - all share same core network backhaul. Western countries who did deployed 3G many years back are going into hybrid path of taking 3G to 4G apart form offloading peak data to (wired) broadband networks. They are promoting use of wifi, bringing new gadget FemtoCell. At this time, it doesn’t makes sense to say - 3G is everything! Latest capping on uncapped 3G plans by AT&T is a good example of that.