FAQ : Connectivity (Tunnels and Subnets) : The tunnel is slow

Other FAQ sections

The tunnel is slow

SixXS PoPs themselves are generally connected to the ISPs network at at least 100mbit, in many cases at 1Gbit and a few are even connected at 10Gbit to the datacenter of the ISP that hosts the PoP.

Do note that PoPs are shared resources and they terminate sometimes thousands of users, as such, even if the PoP has proper connectivity there are others who are using that too. SixXS does not shape or limit the speeds of tunnels, the only limitation is a physical one.

One of the requirements for a PoP placement is that proper external connectivity is also available, thus that the ISP is properly connected at various IXs. This though does not guarantee that the path between your endpoint and the PoP or between you has sufficient capacity.

Connectivity being 'slow' can be caused by a myriad and combination of factors:

• Capacity of the IPv4 forward and reverse path between your IPv4 endpoint and the PoP
• Capacity of the IPv6 forward and reverse path between the PoP and the remote destination
• "QoS"¹ rate limiters on the IPv4 or IPv6 path between your endpoint and the destination
• MTU issues on the IPv4 or the IPv6 path
• MTU size itself of the path: smaller paths tend to have less throughput
• CPU limitations on your tunnel endpoint, which can especially be a problem when using AYIYA, due to signature generation and verfication, on slower CPUs

¹ = see QoS at ISPs / Network Neutrality below for more details

IPv6 SpeedTest

There are a couple of online IPv6 SpeedTests, a few are listed below, Google/Bing/Yahoo have more. Note that these servers tend to not be local to the PoP and thus they are under full influence of the factors mentioned above and the load on those servers themselves, thus results might vary heavily.

• IPv6 Test's SpeedTest - also compares IPv4 + IPv6 speeds
• ipv6-speedtest.net/

What can one do when the connectivity is extremely 'slow'?

Firstly realize that you are on a free and shared system, as such if your tunnel endpoint has a 1Gbit IPv4 link please don't expect you to be able to use that fully towards every destination around the world. In the spirit of fair use that would also be quite a bad assumption.

Several PoPs are able to easily push at least multiple 10s of megabits per tunnel. But of course, when 10 people do 10mbit of traffic, a 100mbit port would be full. As such, if you are able to do more than multiple mbits, the speedtest should be fine.

If your connectivity is only a few 100s of kilobits/sec, please verify, as much as possible, the above points and provide these details to our contact address so that we can check up with the PoP in question if there is something wrong with the PoP or with the provided connectivity.

QoS at ISPs / Network Neutrality

Various ISPs configure so called Quality of Service (QoS) on their network. Generally they prioritize HTTP, deprioritize any filesharing and also for them unknown protocols like protocol 41 and AYIYA that are used by SixXS tunnels.

If your ISP thus has this configuration these tunnelling protocols are slowed down significantly. Ask your ISP if they are performing any "QoS" on your connectivity or better, ask them if they support Network Neutrality in general.

Also see the Network Neutrality article on Wikipedia for more details on this subject.