My VDSL Install Experience

Hi everyone,

I'm Erin, MD at Unleash, and I thought I'd provide a few clarifications for what help it may provide.

Yes, we do provide VDS2 to home users, or any type of premise where the service is available. Our focus is predominantly on commercial users, but there's a fair bit of overflow into enthusiasts and heavy users.

Our network fully supports native IPv6 everywhere except, unfortunately, on Telecom ADSL/VDSL circuits. We're working on this and it won't be far away. Stay tuned.

The sync speeds on an ADSL or VDSL line are the maximum attainable speeds under ideal conditions, and of course there are a lot of factors which can cause the speed to be less. The first is simply the nature of TCP, in that a steady stream of acknowledgement packets has to be sent back to the other end of any data stream, and it doesn't take much for the occasional re-transmission to be required, which brings the speed down quite sharply. Something like 80% throughput is probably a good target for "full speed" on a TCP stream. Sometimes cramming lots of TCP streams together will allow an aggregated speed a littler higher than can be achieved on one stream.

The second factor is contention. Telecom does not provide the full bandwidth from the ISP to the customer. In fact, the default dedicated bandwidth per customer on VDSL2 is only 96kbps. This limitation is present within Telecom's network, and also applied at the interface between Telecom and the ISP. So at busy times, it's unlikely your real speed will always match your sync speed.

One of my colleagues has just done a test from a machine on a 100Mbps interface connected to the router your circuit terminates on, and achieved 80Mbps to linux.citylink.co.nz (this is generally not a bad indicator of maximum attainable line speeds as the servers are fast, local, and apparently well configured!). From a faster-connected box elsewhere in our network, we can achieve ~400Mbps, so it seems there is plenty of bandwidth from us to them. This suggests the issue in your case is likely to be between us and you in the Telecom network. However, VDSL offers limited guarantees of performance, so unless we can turn up something misconfigured, probably this is as good as it gets and your performance reflects demand on your local exchange and associated connectivity.

On the subject of linux.citylink.co.nz, in the directory there, there should be a file called this-node-XXX, where XXX will be a three letter code corresponding to the city where the server is located. I imagine you are looking at this-node-AKL, which is the Auckland server, but let me know if it's not.

There are also factors which limit the speed once you get beyond the ISP out onto the internet, and of course it's conceivable that an ISP's upstream connections can be saturated at times. In the case of Unleash, this is generally not so, as our predominantly commercial customer base demands consistent performance, and we upgrade our links when they reach the point of being saturated even for very short periods of time. We sell both dedicated and contended bandwidth, but our contended product (the stuff you get on a VDSL connection) is not very heavily contended.

Bandwidth delay product can also be a significant factor in speed, particularly where the other end of the connection is geographically far away (and thus has a high round trip time).

In short, your speed can be constrained to less than the sync speed before you even get to the ISP, within the ISP, and upstream of the ISP on the wider internet. In your case, it looks like the issue is predominantly the first one, but we'd be happy to look into it a little further.

In response to one or two other questions, we do not have VDSL2 pricing on our website (my apologies - do feel free to get in touch for pricing), we can - as networkn has indicated - pool data plans across several connections, provide IPv4 subnets, and we can separate domestic and international data for billing purposes.

I can also comment generally on some of the VDSL2 CPE currently available. We have used the Thompson TG789vn with good success, and while this model has a number of bugs, they are all patch-able, and the support from the distributor of these modems is top notch. We've used the Cellpipe 7130 (iirc) which seems reliable but is less feature rich and less configurable than the Thompson, but we've not turned up the odd bugs present in the Thompson. We're also looking into some Zyxel options and networkn I gather is using one of these. Keen to hear your thoughts!

Cheers,

Erin

networkn

Nomlas