But I thought
TATA was the best in case of International routing? I'm pretty sure Airtel is the best Nationally but I hoped TATA was the better Tier 1 ISP here.
It depends on destination but typically for networks with large traffic volumes you will find Airtel, Jio etc (in Indian context) doing better than Tata Comm specifically in terms of latency and here's why:
Tata Comm AS6453 is a transit free (sometimes also called as tier1 network). They are one of 15-16 networks (list
here on Wikipedia) in the world which can reach all networks directly (as they are it's customer) or indirectly as they are customer of it's remaining 15 peers. So typically a transit free network peers only with another large transit free network and would typically have a closed peering policy. So one side here is their (downstream) customer in India like say Siti, ACT, Excitel, etc. Other side is either their peerings with other large transit free networks or simply their customer in US/Europe. This is quite different from a network like Jio, Airtel etc which would have more relaxed peering policy and infact would actively reach out to large networks outside of India to peer (for free). They would pick traffic in US/Europe/Singapore via direct peering (PNI) over internet exchanges.
So if I am a content player and have to send traffic to a customer of Tata Comm (and other similar large transit free networks with closed peering policy) I would have to pay Tata Comm directly or have to pay any other large network which peers with them. This can make routing quite bad in certain areas. Transit free networks typically do not peer at any public exchange (they stay there to sell IP transit over the IX but do not peer openly) and that further degrades the quality. This reduces the "entry points" in a given backbone. Plus people typically have more capacity towards their peers compared their transit.
So here's a real world comparison:
innog.net (164.52.202.232) that's routed behind Tata Comm AS4755 behind AS6453 while IP of my provider in Haryana (IAXN) - 202.9.120.253 is routed behind Airtel. Let's check latency from all RIPE Atlas probes in Singapore towards each of them. Expected latency should be less than 90ms as both end points are within Delhi NCR region.
RIPE Atlas Singapore -> innog.net via Tata Comm (results
here)
16 out of 50 probes had a latency of over 100ms. 5 out of 50 probes have over 150ms latency.
RIPE Atlas Singapore -> 202.9.120.253 via Airtel (results
here)
2 out of 50 probes had over 200ms latency. Rest all with less than 82ms latency.
Why this difference - because aggregate of IAXN's IP (202.9.120.0/24) is visible at Equinix Singapore to
all these networks while for innog.net covering aggregate (164.52.202.0/24) entry has to be a customer of Tata Comm or customer of a peer of Tata Comm within Singapore or a customer of customer of Tata Comm etc. Another factor is that within India both Airtel & Jio are large eyeball networks. They hold end customers and hence many content networks optimise their routing with them & focus on them instead of a backbone transit/enterprise network like Tata. Take case of
Cloudflare - they have nodes inside Airtel, Jio etc across India and typically latency is way lower on Airtel/Jio.
Here's trace to Cloudflare 1.1.1.1 from innog.net server from Noida:
anurag@host01:~$ traceroute 1.1.1.1
traceroute to 1.1.1.1 (1.1.1.1), 30 hops max, 60 byte packets
1 e2e-68-1.ssdcloudindia.net (164.52.200.1) 2.524 ms 2.807 ms 3.061 ms
2 180-179-210-65.static.e2enetworks.in (180.179.210.65) 0.370 ms 0.448 ms 0.547 ms
3 180.179.197.217 (180.179.197.217) 0.671 ms 180.179.197.205 (180.179.197.205) 0.572 ms 180.179.197.217 (180.179.197.217) 0.776 ms
4 14.141.116.105.static-Delhi.vsnl.net.in (14.141.116.105) 1.236 ms 1.308 ms 219.65.44.177.static-delhi.vsnl.net.in (219.65.44.177) 0.816 ms
5 * * *
6 115.114.85.222 (115.114.85.222) 36.405 ms 36.012 ms 35.978 ms
7 14.142.39.21.static-Mumbai.vsnl.net.in (14.142.39.21) 38.711 ms 39.109 ms 38.526 ms
8 * * *
9 * * *
10 * * *
11 * * *
12 one.one.one.one (1.1.1.1) 42.630 ms 42.246 ms *
anurag@host01:~$
It goes to Mumbai even when via Airtel it is much lower. Here's what I get from
their looking glass DEL1 PoP:
Fri May 21 21:33:04 GMT+05:30 2021
ping inet 1.1.1.1 count 5
PING 1.1.1.1 (1.1.1.1): 56 data bytes
64 bytes from 1.1.1.1: icmp_seq=0 ttl=61 time=1.666 ms
64 bytes from 1.1.1.1: icmp_seq=1 ttl=61 time=1.702 ms
64 bytes from 1.1.1.1: icmp_seq=2 ttl=61 time=2.490 ms
64 bytes from 1.1.1.1: icmp_seq=3 ttl=61 time=2.645 ms
64 bytes from 1.1.1.1: icmp_seq=4 ttl=61 time=4.448 ms
--- 1.1.1.1 ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max/stddev = 1.666/2.590/4.448/1.011 ms
{master}
lookingglass@DEL-ISP-ACC-RTR-49>
With that being said please remember that peering, interconnection etc is one element of the whole connectivity picture. There are many other things including capacity on transport, submarine cable agreements, overall finances, middle mile network, last mile delivery network etc. All that impacts numbers, uptime etc. My experience has been that Tata Comm is much better engineered backbone. Typical latency between point A to B within their network - Tata Comm is slightly lower than Airtel. Plus also the fact that a large part of traffic these days concentrates on a few ASNs and hence latency optimisation has diminishing returns once you have good routing to say top 20-30 ASNs in terms of traffic. Airtel/Jio etc would typically have better routing within Asia but amount of traffic flow is actually lower. (As a network engineer I would still love to see it being optimised though for peer to peer VoIP traffic etc)
I my city in Haryana I have 14-15 options for FTTH and actually I feel worried by fact that 10 out of them run over Airtel circuits and it's becoming a massive single point failure. It's not a Airtel issue but the fact that they are more aggressive in wholesale market & in many cases are the only option. The ones not on Airtel are: Jio fibre, BSNL, Railwire LCO and Excitel (strong guess as they would typically prefer Tata Comm). Rest everyone is taking Airtel circuits for transit as well as peering.
Disclaimer: Posting here in my personal capacity and I do work for a global IP backbone which does follows a open peering policy.