I doubt unless you're using VPC peering, Transit Gateway, or Private Link that it would be the case that user-generated traffic between regions (for ex, between EC2 instances in Dublin and Sydney) is automatically routed through their backbone. Can you point to the re:Invent presentation? Genuinely curious.

It really is, for all AWS-AWS traffic barring Beijing and Ningxia. src: I worked in AWS networking for 2.5 years

here's DUB->SYD:

HOST: amazon02.ring.nlnog.net Loss% Snt Last Avg Best Wrst StDev

  1. AS16509  ec2-3-248-240-73.eu  0.0%    10    7.1  22.8   1.0 125.7  38.1

  2. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

  3. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

  4. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

  5. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

  6. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

  7. AS???    100.65.15.3          0.0%    10    0.8   1.1   0.2   6.7   2.0

  8. AS???    100.95.19.145        0.0%    10    0.3   1.4   0.2   5.5   1.9

  9. AS???    100.100.4.12         0.0%    10    0.3   1.1   0.3   7.0   2.1

 10. AS???    150.222.242.237      0.0%    10  254.0 254.0 253.9 254.4   0.2

 11. AS???    52.95.36.164         0.0%    10  257.2 255.7 254.0 257.3   1.3

 12. AS???    150.222.112.139      0.0%    10  253.4 253.9 253.4 255.1   0.5

 13. AS???    150.222.112.142      0.0%    10  259.6 257.8 255.5 266.8   3.5

 14. AS???    52.95.36.143         0.0%    10  255.3 256.1 255.2 261.4   1.9

 15. AS???    52.95.38.17          0.0%    10  255.0 255.6 254.9 259.9   1.6

 16. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

 17. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

 18. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

 19. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

 20. AS???    ???                 100.0    10    0.0   0.0   0.0   0.0   0.0

 21. AS???    100.65.16.65         0.0%    10  256.7 279.8 256.7 334.4  26.1

 22. AS16509  amazon08.ring.nlnog  0.0%    10  254.4 254.4 254.3 254.4   0.0

Thanks. To confirm: You're pinging between the EC2s using their public DNS, right?

If AWS backbone is used automagically, I wonder why would anyone pay for Transit Gateways or VPC Peering rather than do mTLS between their cross-region instances or tunnel via Wireguard-esque transports like tailscale or defined.net, for example. Also, since when has this been the case, if you'd know?

I'm curious what the bandwidth charges are for EC2 to EC2 cross-region when using their public IPs / DNS? Same as VPC Peering?

Yep, public IPs. I’m sure people do that, or use VPC peering if they want to use private IPs.

Expensive. VPC peering serves a different purpose, but pricing is the same.

Thanks a lot.

> Expensive.

VPC Peering bandwidth rates are $0.01 / GB. EC2 (public Internet?) bandwidth rates are $0.09 / GB. For xfers between EC2 to EC2 via AWS backbone, I assume I'd still be charged the public Internet bandwidth rates, right?

thank you. TIL this