Airtel routing Europe to India via the US
Airtel has been facing routing issues between the EU and India since 8th Dec. There has been a significant increase in latency for many of their downstream ASNs. I have not seen any information in public about submarine cables or transport issues. (If I have missed it, please let me know via the contact page or in the comments here!)
Here’s the chart of average latency from my server in Germany towards a few hundred Indian endpoints.
The actual latency spike is much higher than this average, as the chart includes endpoints behind Tata Communications, Jio, Sify, Vodafone IDEA, etc., which are not experiencing the issue.
Here's an example of latency to Digital Ocean in Bangalore:
Latency is up from 160ms to 260ms with some packet loss in the initial few hours. The jump here is because one leg of the traffic EU -> India is coming from the US. Here’s a trace to this machine from my server on Contabo Germany:
1. AS51167 ip-161-97-128-11.static.contabo.net (161.97.128.11) 0.0% 10 2.7 10.1 1.1 20.5 7.3
2. AS3356 et-4-0-8.edge6.Dusseldorf1.Level3.net (62.67.22.193) 0.0% 10 24.3 12.1 1.6 28.0 9.0
3. AS3356 ae2.3216.ear4.frf1.neo.colt.net (171.75.10.127) 90.0% 10 12.7 12.7 12.7 12.7 0.0
4. AS6461 ae0.mpr1.fra4.de.zip.zayo.com (64.125.12.125) 0.0% 10 4.9 19.3 4.9 42.5 11.2
5. AS6461 ae12.cs1.fra6.de.eth.zayo.com (64.125.26.172) 0.0% 10 154.2 156.8 148.9 166.7 5.3
6. AS6461 ae2.cs1.ams17.nl.eth.zayo.com (64.125.29.59) 80.0% 10 163.3 161.6 159.9 163.3 2.4
7. AS??? ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
8. AS6461 ae10.cs1.lhr15.uk.eth.zayo.com (64.125.29.17) 0.0% 10 156.2 159.0 149.5 173.9 7.0
9. AS6461 ae2.cr1.lhr11.uk.zip.zayo.com (64.125.24.140) 50.0% 10 145.5 154.8 145.5 163.1 6.5
10. AS??? ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
11. AS??? ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
12. AS6461 ae20.cr1.iad21.us.zip.zayo.com (64.125.23.217) 0.0% 10 176.0 162.5 150.4 182.3 10.5
13. AS6461 ae10.cr1.atl10.us.zip.zayo.com (64.125.25.133) 20.0% 10 159.9 165.2 147.4 192.4 14.8
14. AS??? ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
15. AS??? ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
16. AS??? ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
17. AS6461 ae19.ter1.lax12.us.zip.zayo.com (64.125.25.123) 60.0% 10 155.4 157.1 152.8 160.1 3.6
18. AS6461 64.124.194.83.IPYX-289370-901-ZYO.zip.zayo.com (64.124.194.83) 0.0% 10 156.6 163.2 150.0 205.6 16.6
19. AS??? 182.79.153.39 0.0% 10 255.6 261.8 251.7 283.6 9.1
20. AS9498 dsl-tn-190.97.246.61.airtelbroadband.in (61.246.97.190) 0.0% 10 261.4 262.5 255.8 269.1 5.6
21. AS??? ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
22. AS??? ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
23. AS??? ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
24. AS14061 167.71.232.207 0.0% 10 267.8 266.1 259.7 271.9 4.5
Contabo (Germany) → Colt/Lumen (Düsseldorf) → Zayo (Frankfurt) → Zayo (Amsterdam) → Zayo (London) → Zayo (Washington) → Zayo (Atlanta) → Zayo (Los Angeles) → Airtel handover somewhere in the US West → Airtel India → DigitalOcean Bangalore
Checking the latency to hundreds of EU endpoints from my home behind Airtel AS9498, I see latency has come down a bit since the 18th:
Finding overall impact
To get a broad idea of the impact, one can pick up Airtel routes from their upstreams, a mix of Cogent AS174 and Arelion AS1299 etc and find out routes tagged with Europe. Zayo only tags their route as “6461:5998 - Customer with”, no location-specific tags. But looking at Cogent AS174, it includes tags like: “174:21101 - Route is an EU internal or customer route” and Arelion AS1299 includes 1299:30000 - EU Customers.
Picking routes from RIPE RIS RRC05, RRC19, and route-views.linx. Let’s compare routes count of routes between 01 Dec to 21 Dec.
As clearly visible there is a quite heavy drop in terms of routes. Note that routes do still exist in the tables of Cogent and Arelion but they are learning those in the US instead of Europe.
- Missing Prefix/ASNs for AS174 via Airtel in the EU: List here
- Missing Prefix/ASNs for AS1299 via Airtel in the EU: List here
Update - 03:53am IST (GMT+5.5) on 22 Dec 2024
I put primary draft for this post yesterday, left a script to download and crunch routing tables. Today I picked up the data. So while post went up few mins ago, data is around a day old. Just after posting I realised that some of the routes have fixed, while some are still indirect.
