What speed should I expect from my fibre leased line, & what if I'm not getting that?

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What speed should I expect from my fibre leased line?

Posted on 17 August 2021 by Beaming Support

What speed should I expect from my fibre leased line? With a fibre optic leased line, the upload and download rate you agree with your internet service provider should be the speed you get, always.

So, if you’ve run tests and your leased line is not performing as it should, something is not right and your internet service provider should rectify this.

Your ISP should be able to help you understand the problem and eliminate any external factors affecting the speed of your line, but if you do need some help with this, this article will help you to:

  • Understand what speed you should expect from your leased line
  • Eliminate any simple to fix problems that could be affecting your speed test
  • Understand what’s causing the problem
  • Understand what is not causing the problem
  • Get your leased line up to the right speed


What speed should I expect from my fibre leased line?


The speed you pay for

You should get the data transfer rate agreed with your provider, for a leased line this is typically a specific figure within the range of 100Mbps to 10Gbps.


Consistent speeds

There’s no reason for any variation throughout the day as may happen with a broadband connection.


Symmetric upload & downloads

Unlike with broadband, your upload and download speeds should be equal.

Quick checks for when you don’t get the speed you expect from your fibre leased line

If you’ve established that your fibre leased line isn’t providing the speed you’d expect, there are some quick troubleshooting checks that can be completed. These may seem very simple but will help eliminate some easy to fix issues we’ve seen before.

  1. Have you bought a contended product?
  2. Are you confusing your agreed data speed with bearer speeds? For example, you may be contracted to a 100Mbps data connection speed on a 1Gbps capable bearer with the idea that you may scale up requirements in future.
  3. If you share the connection, for example between a group of businesses at a business park this could explain a variation in speed. Try to run your tests when you know none of the other businesses will be using the connectivity.
  4. Are you testing wirelessly? It’s always best to plug in with an ethernet cable and to disconnect from your wireless network when you’re running a speed test.
  5. Is your router configuration correct and fault free?


That’s all been checked, so why is my leased line speed slow?

When you’re sure there’s nothing simple you may have missed, your slow leased line is likely to be down to one of the following.

Your leased line is actually sharing bandwidth

Check with your ISP or review your contract to confirm your guaranteed speeds. Not all ISPs will configure a leased line fibre to provide guaranteed bandwidth. To cut costs they might actually provide a contended connection – essentially shared bandwidth – across multiple connections at the same time. This means your connection only receives some of the maximum speed you were expecting.

Read this article for more on what contended connection is and how to get low contention or uncontended connectivity.

An ISP that has its own network will have more control over its design and bandwidth use than a re-seller that puts their name to another provider’s network, so when you choose a provider, asking whether they control their own core network is wise.

Something’s slowing down your local area network

There is a possibility that on testing, your ISP finds no problem with the leased line connection and suggests that your tests return slow speeds because of problems on your firewall or local area network.

If you are in charge of your company’s IT support then you’ll have a good idea of whether this is the case, but if your IT is managed externally, give them a call to see what they suggest.

We understand the frustration this kind of back-and-forth can cause, especially when no one seems able to resolve the problem. When you find this happening, it’s a good time to consider how working with a managed service provider that handles both your internet connectivity and internal network may save you considerable time and hassle.

What’s not causing the problem?

Look out for red herrings, if your ISP tries to blame your location then be skeptical. It’s extremely unlikely this is causing the problem for fibre delivered across Openreach’s network. The network design of alternative network providers is different and this may be a more valid explanation when it comes to their services.

Fibre leased line technology is not affected by distance from an exchange and therefore properties would not suffer any degradation in the quality of your connection using dedicated leased fibre.

How can I improve the speed?

Your ISP should offer service level agreements (SLAs) to back up their speed guarantee and as such performance can be managed against these.

If your business has grown to the extent that you do not have enough bandwidth, it may be time to upgrade and if you are not getting great customer service, it may be time to change provider.  Although you cannot migrate a fibre, changing ISP can be made a lot easier if you choose a provider with good IT knowledge.

Beaming has a good track record of making changing across to our network as smooth as possible due to the expertise of our technical team.

To find out how you can move your leased line connectivity to Beaming for guaranteed high speed, call our friendly team on 0800 082 2868 or fill in the form below.

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Fibre leased lines in action

The Kurt J. Lesker Company improved international communication with a 500x boost to their internet connection

Kurt J Lesker
  • Fibre
  • Manufacturing
  • Data Security

Kurt J. Lesker Company

For security reasons, all of the Kurt J Lesker Company’s data is held at its US base. This means the speed & security of the data connection between the US & the UK is crucial to the effective operation of KJLC’s business.

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