Another Case Of Bad Routing: Vi and Airtel

Table of Contents

Even though Bharti Airtel (AS9498) is an upstream of Vodafone Idea (Vi) the routing between the two ISPs is consistently bad. While this heavily affects P2P traffic, it also has other impacts.

➜ VoWiFi (Voice Over WiFi) is very useful for places which have poor cellular coverage, But due to the horrible routing between the two ISPs the VoWiFi experience is bad. When I use VoWiFi (Vi SIM) on Airtel Broadband connection, there are constant call drops and stuttering.

➜ 3GPP (Third Generation Partnership Project) has defined a number of network domains that are used to describe different parts of the cellular network architecture.

The domains used for VoWiFi look like this: epdg.epc.mnc022.mcc404.pub.3gppnetwork.org

MCC stands for Mobile Country Code, and it is a three-digit code used to identify the country where a mobile network operator is based. The MCC is assigned by the International Telecommunication Union (ITU) and is used in combination with the Mobile Network Code (MNC) to uniquely identify a mobile network operator.

Now let’s take a look at this traceroute:

fawks on phoenix ~ took 1s 
➜ mtr -wr epdg.epc.mnc022.mcc404.pub.3gppnetwork.org 

Start: 2023-05-01T14:42:16+0530
HOST: phoenix                Loss%   Snt   Last   Avg  Best  Wrst StDev
  1.|-- 2401:4900:1c02:526c::   0.0%    10    0.4   0.4   0.4   0.5   0.0
  2.|-- 2401:4900:1c02:8fff::1  0.0%    10   13.8  20.1  13.6  48.0  11.3
  3.|-- 2404:a800:2a00::2a5     0.0%    10   14.3  15.0  14.0  18.3   1.4
  4.|-- 2404:a800::204         50.0%    10   44.6  44.9  44.1  45.8   0.7
  5.|-- 2404:a800:1a00:803::7a  0.0%    10  103.6 103.1 102.2 105.9   1.1
  6.|-- 2402:6800:760:7::72     0.0%    10   87.5  88.8  87.5  92.5   1.5
  7.|-- 2400:5200:1400:72::1   20.0%    10  104.9 103.2 102.3 104.9   1.1
  8.|-- ???                    100.0    10    0.0   0.0   0.0   0.0   0.0
  9.|-- 2402:3a80:1060::3       0.0%    10  103.8 105.0 103.7 108.1   1.7

Look at the 6th hop, 2402:6800:760:7::72 belongs to AS55429 Limelight Networks India, which is one of the downstreams of Bharti Airtel (AS9498) why is it routing through that?

If are a user using Vi internet, the routing is even worse.

➜ mtr -wr 2402:8100:3149:9ee8:2859:60ff:fedf:1ac6      
Start: 2023-05-01T15:08:48+0530
HOST: phoenix                                              Loss%   Snt   Last   Avg  Best  Wrst StDev
  1.|-- 2401:4900:1c02:526c::                                 0.0%    10    0.6   0.5   0.3   0.6   0.1
  2.|-- 2401:4900:1c02:8fff::1                                0.0%    10   14.8  19.1  13.4  35.1   8.4
  3.|-- 2404:a800:2a00::2a1                                   0.0%    10   33.8  24.8  14.1  43.0   9.7
  4.|-- 2404:a800::147                                        0.0%    10  125.4 126.0 123.3 133.8   3.8
  5.|-- ???                                                  100.0    10    0.0   0.0   0.0   0.0   0.0
  6.|-- port-channel12.core2.fra1.he.net                      0.0%    10  138.5 138.7 138.0 140.0   0.7
  7.|-- level3-as3356.10gigabitethernet3-7.core1.fra1.he.net  0.0%    10  139.8 140.5 139.8 141.8   0.7
  8.|-- lo-0-v6.ear2.London1.Level3.net                       0.0%    10  152.9 152.8 152.1 153.9   0.6
  9.|-- 2001:1900:5:2:2::7e3e                                20.0%    10  241.3 241.8 241.2 242.9   0.6
 10.|-- 2400:c700:0:370::f2                                  10.0%    10  231.3 231.6 231.0 232.6   0.5
 11.|-- 2402:8100:4000::7bb                                   0.0%    10  230.6 231.2 230.6 232.7   0.8
 12.|-- 2402:8100:4000::613                                   0.0%    10  252.7 250.0 248.8 252.7   1.1
 13.|-- 2402:8100:4000::7e4                                   0.0%    10  230.9 230.8 230.0 231.6   0.6
 14.|-- 2402:8100:4000::5fd                                   0.0%    10  247.1 247.9 247.0 250.5   1.1
 15.|-- ???                                                  100.0    10    0.0   0.0   0.0   0.0   0.0
 16.|-- 2402:8100:4000::7a8                                   0.0%    10  229.6 229.3 228.7 230.5   0.8
 17.|-- fd00:0:17:17::72                                      0.0%    10  247.6 247.1 246.5 248.2   0.5
 18.|-- ???                                                  100.0    10    0.0   0.0   0.0   0.0   0.0

It goes from:

India (Airtel) ➜ Germany (HE.net) ➜ UK (Level3) ➜ India (Vi) with RTT of more than 200ms

I tried connecting from my Vi LTE through a VPN to my server at home, it’s literally unusable: very high latency along with packetloss. They need to do something about this.

Also, Vi seems to be using an IPv6 ULA (fd00:0:17:17::72) in their network instead of using GUA for everything. This is against best practices.

Anyway, Thank You for reading. You can contact me here in case of any questions: https://shrirangkahale.com/contact

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