Do I Really Need A Leased Line?

This article is aimed at anybody who is considering a leased line for their company ‘s internet access but is not sure if they can justify the cost. It sets out what I think is the next best set up to a leased line and looks at where it does, and does not, measure up. This article is written from a UK perspective but the principle is valid anywhere.

Leased Lines: An Overview

A leased line is a connection to the internet or specific site which delivers reliable bandwidth that is not shared with anybody else. Unlike ADSL broadband, if it says 2Mb you will actually get 2Mb, upload and download, full duplex. This can be delivered over copper or fibre. Sounds good? It is, but leased lines are also more than a little bit scary:

  • They are very expensive. Typically they cost £400 to £600 per month for 2Mb.
  • You have to commit to a minimum contract period which won’t be less than a year.
  • They will require a BT/OpenReach engineer to attend your site and install lines. Even though the service provider should arrange everything with them you will probably discover that OpenReach are not an easy organisation to deal with.
  • Unless you go for a managed router (more expense) you may have to learn about BGP, X.21 and other nasty protocols. If all you know is ADSL then this will be a steep learning curve. Don’t assume that the router you bought for ADSL will handle it.

If you really need a leased line then you need to bite the bullet and get on with it. If you are not sure then read on…

What Else Is There?

Lets have a look at what else is available. You almost certainly already have one of these solutions but they can be combined in interesting ways.


ADSL is standard home and business broadband. Business products have a slightly better contention ratio than home products. It is asymmetric meaning that the upload speed is a lot less than the download speed.

ADSL goes “up to” 8Mb and ADSL2+ goes “up to” 24Mb. As you probably know, “up to” can mean almost anything depending on your location and the quality of your cabling. It sure as hell doesn’t mean that anybody is going to get 24Mb because you always lose about 1/8th of the headline speed in overheads even on an ideal line. Contention ratios on business products are typically 20:1 so, provided the ISP is honest, you can regard 5% of the maximum bandwidth as more or less “guaranteed bandwidth”, although the ISPs certainly won’t use that term. Upload speeds vary by ISP. The best I am aware of is “up to” 2.5Mb with Be*. That costs £22 per month for their “Be* Pro” service.

A “guaranteed” upstream bandwidth of 125kb may not sound like much but it should carry a few VoIP trunks. Latency might be an issue though. Maybe using it for telephony is a step too far. That said, maybe it has value as a backup for your main telephony connection…


SDSL is a symmetric DSL service. It uses similar technology to ADSL. Its bandwidth is 0.5, 1 or 2 Mb and it is normally only offered to customers who stand a reasonable chance of getting those speeds. Of course there is still the overhead to subtract. Contention ratios on SDSL products are always 10:1 so you can regard 10% of the maximum bandwidth as more or less “guaranteed bandwidth”, although the ISPs won’t use that term. SDSL is expensive. Zen wants £300 a month for 2Mb. If you find that attractive you are probably better off moving straight to their 2Mb leased line with a headline cost of £330 (plus extras).


In the UK, cable means Virgin Media but Virgin Media Business does not always mean cable. You need to check whether they offer genuine cable in your area. If they do then they offer up to 20Mb down and 1Mb up. They boast that these are the speeds you really do get. Of course this is not a leased line and there is a contention ratio. I can’t find any information of what that is though. I can’t imagine it is worse than 20:1 and it might be better. It costs £50 a month.


3G is a wireless service running over the 3G mobile phone network, dropping back onto the 2.5G network when necessary. Speeds depend on location and reception. Like any wireless technology, it is less reliable than wired. You wouldn’t run your company broadband over this unless you had to.

What Is The Optimum Leased Line Alternative?

I am going to assume that your principle objection to the above solutions is reliability not bandwidth. If it is bandwidth, particularly guaranteed upstream bandwidth, then you are probably going to need a leased line, at least until the next generation of cable comes along.

Leased line alternative: Multihoming with three ISPs.

The trick to gaining reliability is to have multiple paths to the internet with no single points of failure. This is called multi-homing. Ideally you want a cable connection and an ADSL+2 connection. That way you can avoid the BT exchange as a single point of failure. If you can’t get cable then you have to accept that risk and use two ADSL2+ connections. You want to use different ISPs and make sure that they do not run over the same infrastructure (for example, O2 and Be* use the same network, so don’t go for both of them). We top this off with a 3G dongle for backup, in case some moron cuts every cable entering your building, like morons sometimes do.

Finally, you need some way to failover incoming connections. The easiest way to do that is by using a dynamic DNS service. This isn’t perfect. It is not instantaneous and any connections in progress will die but it does mean that your alternative connection will be getting the incoming traffic within a minute. The only time this doesn’t work well is when your main connection fails into a very slow or unreliable mode of operation which the router does not recognise as a full failure and hence fails to failover. This is suitable for extranets and the like. It is not suitable for serious e-commerce but everybody gets that stuff externally hosted anyway, right?

A router that can do all this is not expensive. Draytek do a few routers with dual WAN plus 3G backup. They also have a reasonable firewall built in and can load balance outgoing connections. Plus they are fairly easy to configure. I really like them. Of course, there are other brands with similar abilities in that price range.

Another really big advantage of this set up is that users are probably not going to notice disruption if you chuck over one of your three ISPs . A traditional leased line locks you in with one ISP and you would normally have ADSL with the same ISP as a backup. This alternative gives you more freedom to change the ADSL or 3G provider and maintain best value for money.

You are looking typical monthly costs of £50 for cable (Virgin Media), £22 for ADSL2+ (e.g Be*) and £15 for the 3G dongle (e.g. T-Mobile). Dynamic DNS is only few dollars a year from DynDNS. That is a lot of savings compared to a leased line. For many companies it will be quite good enough.

For savings around £3,000-£5,000 a year it is certainly worth thinking about.


May 5, 2010. IT, Sensible.

One Comment

  1. Aziz replied:

    Pfsense is a good router/gateway that can handle multiple WANs and it’s all free (freeBSD).

    BT Infinity is also another option in some parts of the country.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Trackback URI

%d bloggers like this: