Better download throughput over IPv6?

I have recently noticed that downloads from Cloudflare are much faster when connected over IPv6.

I have a Workers endpoint that proxies a 10 GB blob file from Backblaze B2. The download peaks at 0.9 GiB/s and remains around +750 MiB/s over IPv6 while 40-120 MiB/s over IPv4.

Is this normal, or how can I ensure if my server provider is throttling IPv4 traffic?

Download command:

aria2c -x 8 -s 8 --interface <YourIPv6IP> --async-dns=false -i list.txt

list.txt:

https://<REDACTED>.workers.dev/10GB.bin
        dir=/dev
        out=null
        allow-overwrite=true
        file-allocation=none
https://<REDACTED>.workers.dev/10GB.bin
        dir=/dev
        out=zero
        allow-overwrite=true
        file-allocation=none

Here is the code:

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) {
  const url = new URL(request.url)
  return await fetch('https://<REDACTED>.s3.eu-central-003.backblazeb2.com' + url.pathname, request)
}
1 Like

Hi there,

This is an interesting one, do you see similar behaviour with Backblaze when you go directly over ipv6 / ipv4 do you see performance similar to when going over Cloudflare?

It does sound like it is related to your ISP and their throttling / performance strategy when it comes to ipv6 vs ipv4.

3 Likes

I can’t test directly against Backblaze over IPv6 since they have no support for IPv6.

IPv4-wise, I get similar speeds to what I get from Cloudflare over IPv6.

I will try with another provider to see if it’s the same.

1 Like

I tested downloads a while back against IPv4 and IPv6 paths. This was a global test, from many different countries. I did notice that in some areas, IPv6 performed better. My guess is that the equipment along those paths is newer and better, but that is just a guess, really.

1 Like