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ChrisJenkins
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What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. slow!

Like many people I am well past fed up waiting for VM to deliver IPv6 support so for some years I, like many people, have been using a tunnel broker (in this case tunnelbroker.net and tunnelbroker.ch) to provide a transparent IPv6 Internet connection via a 6in4 tunnel between my router and the tunnel broker end point. These tunnels use a standard Internet mechanism to 'tunnel' IPv6 over an IPv4 connection; this is known as protocol 41 (tunnelling protocol).

Functionally this works fine but performance wise it is terrible; the traffic through the tunnel is somehow capped at ~20 Mbit/s. Now you might say that this is due to my equipment, or to the tunnel broker, but this is not the case. Also, many, many other people have reported the same issue with Virgin Media in various forums.

I now have indisputable evidence that something in the Virgin Media network is throttling protocol 41 traffic; what I don't know is if this is deliberate or due to some kind of misconfiguration etc. What is my evidence I hear you ask? Well, it is quite simple really...

Experiment 1

Connect my Mac directly to my SuperHub 3 (running in modem mode). Create a 6in4 tunnel from my Mac to a TunnelBroker.net endpoint in London. Perform speed tests over IPv4 and IPv6. Observe that I get super speeds from IPv4 (I can easily reach > 300 Mbit/s) but I cannot exceed ~20 Mbit/s over IPv6.

Repeat this test using different TunnelBroker endpoints (Amsterdam and Zurich). Same result. Then try with a different tunnel provider (tunnelbroker.ch). Same result.

Experiment 2

Same setup as experiment 1 but this time I setup a VPN connection from my Mac to my VPN provider (NordVPN). This VPN connection is an IPv4 only connection. Then I create the 6in4 tunnel from my Mac, via the VPN connection, to the tunnel endpoint. Perform speed tests over IPv4 and IPv6. Now I get close to maximum throughput (well over 300 Mbit/s) from both IPv4 and IPv6.

Repeat tests with different tunnel endpoints and providers but again via the VPN. Same result, speed is great; no throttling observed.

In both cases the IPv4 traffic carrying the tunnel is going over the VM network. The difference is that in experiment 1 the VM network can 'see' that the traffic is a 6in4 tunnel (protocol 41) whereas in the second one it cannot (as the traffic is encapsulated with the encrypted VPN traffic).

So realistically the only logical explanation is that the VM network is doing packet inspection/filtering and either deliberately or accidentally is massively slowing down protocol 41 traffic, perhaps due to some (incorrect) traffic shaping rules.

Virgin media - which is it please? And why? And will you please stop!

I pay for a high speed connection and I also need IPv6. Since you are years late in delivering native IPv6 then please do not penalise me by making my (and many other customers) alternative IPv6 solution dog slow!

 

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legacy1
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Alessandro Volta
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Message 2 of 13
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Re: What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. s

IPv6 will just not happen for many more years to come...
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gary_dexter
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Alessandro Volta
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Message 3 of 13
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Re: What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. s

Since they don’t officially support IPV6 they have no reason to allow full speeds to it. 


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Anonymous
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Re: What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. s

your tests are inconclusive. you changed the route used when you used the VPN. it could be a peer or routing between the 2

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ChrisJenkins
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Message 5 of 13
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Re: What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. s

Sure the routing changes a bit but only for the IPv4 traffic part. Since I get full speed on IPv4 with and without VPN seems unlikely routing is a major factor. If a routing difference can consistently throttle 6in4 traffic to ~20 Mbit/s across several different endpoints and tunnel providers then the Internet is badly broken.

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ChrisJenkins
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Message 6 of 13
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Re: What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. s

So you'd be fine if they throttled VPN traffic, Netflix etc. etc? They have no reason to throttle protocol 41 or 6in4 traffic and indeed much to gain (happy customers).

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ChrisJenkins
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Message 7 of 13
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Re: What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. s

Indeed, hence my issue with them crippling alternative solutions. What point are you trying to make?

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gary_dexter
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Alessandro Volta
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Message 8 of 13
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Re: What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. s

Change to a supplier that supports IPv6?


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ChrisJenkins
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Message 9 of 13
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Re: What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. s

None in my area offering speeds above 20 Mbits or I’d have been gone long ago.

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Anonymous
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Message 10 of 13
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Re: What is Virgin Media doing to protocol 41 and how can we get them to stop doing it? 6in4 tunnels v. s

so why do you really need IPv6. What does IPv4 only stop you from accessing
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