The PlusNet Broadband 'Blueprint'

This article provides a 'blueprint' or overview of how we design and supply our broadband products. It should answer most questions about the performance that can be expected when using our service. We also detail how we expect things to change in the future as usage demands grow.

You should read this article alongside The Future of Traffic Management, and Managing our Network Under Abnormal Load guides.

1. Broadband 'blueprint' introduction
2. How do ISPs design broadband products?
3. How does PlusNet ensure an optimal service for 99% of customers?
4. PlusNet's existing product designs
5. What has happened since April 2006?
6. Network expansion and central capacity
7. BT IPStream vs. Wholesale Broadband Connect
8. What makes PlusNet different?
9. The future
   
   

1. 'Broadband 'blueprint' introduction
Our aim is to supply an excellent broadband service for the 99% of customers who use our products in the way they are designed. However, there will always be a small percentage of customers who push the 'average' above the intended usage design. Below we explain why that matters and how we deal with this to ensure that all customers receive good value and a fair service.

Our products are designed and built based around the financial contribution each of our customers make. Coupled with traffic management and prioritisation, our approach ensures that everyone receives what they have paid for, over a network which we believe will perform more elegantly than that which any of our competitors provide. We always ensure that our PAYG products are given the highest priority for usage, because they contribute exactly what they use.

2. How do ISPs design broadband products?
To maintain growth and achieve profitability ISPs must make sure that their pricing is competitive within the market. Pricing for broadband products has been largely dictated by the wider industry, and this especially applies to 'entry level' products where prices have tumbled in recent years.

ISPs have numerous fixed costs, and must either pay wholesale providers for the broadband network capacity their customers use, or make long term capital investments in building their own comparable network. Every ISP has taken a similar approach to handling this so far, regardless of whether they sell 'unlimited', 'Pay as You Go' or 'limited usage' broadband accounts. Typically the approach is to assume that not all customers will use the full potential of their connection at the same time, even if they have an active connection.

With 512Kbps connections as an example, the available network was shared amongst active customers at a ratio along the lines of 30:1 for a premium service and 50:1 for lower cost 'entry level' products. This sharing of the network is known as 'contention'. Alongside this, another variable that comes into play is "concurrency", i.e. the assumption of how many customers will be logged on and actively using their connection at any one time.

This approach was fine when most connections were provided at 512K and broadband usage was relatively low in volume and bursty by nature, (most people used their connections primarily to browse the web or receive email). Then, ISPs only had to deal with customers who had usage habits which pushed the overall usage levels past a point that was profitable. This has mainly been achieved by limiting certain types of traffic or by directly targeting customers who, through sustained heavy usage, push up the overall usage average.

The broadband world has evolved rapidly, and usage habits are now much more diverse. The trend has seen consumer demand develop faster than the underlying infrastructure and the associated wholesale costs. Broadband connections are used more constantly and broadband itself can no longer be regarded as a 'bursty' service.

This all works against a contended network model, especially because standard connection speeds have increased but underlying fixed and capacity costs have remained the same during the last few years. As such, contention ratios have naturally had to change. As speeds exceeding 2Mbps have become the norm and usage has become more “constant” instead of “bursty” then contention ratios have gone up across the industry. You can read how we plan to develop our broadband network to meet these increasing usage and speed demands in our Future of Traffic Management.

3. How does PlusNet ensure an optimal service for 99% of customers?
We use traffic prioritisation and management and provide reporting to customers which gives an unparalleled view of how a broadband platform operates.

An unmanaged network allows the usage of a small minority to impact the experience for everyone. Applications such as P2P (file sharing) and Binary USENET can easily swamp all of an ISP's available capacity, resulting in network congestion and slowdowns. This is especially frustrating for people who want to use interactive protocols such as web browsing or video streaming without delays. Our advanced technology makes sure that this interactive traffic is always treated in the most efficient way possible. Using these techniques we can allow large downloads to take place when the network is not fully used, but still make sure that customers are able to use interactive services all of the time.

PlusNet's products are designed around 'peak' usage requirements. This reflects how ISPs pay wholesale providers for the capacity their customers use.

Key to diagram

	Fixed broadband line rental cost		BT network charges
	Our network charges		Total end cost

We currently operate two types of product:

• PAYG products - where paid-for usage directly relates to the amount we spend on capacity for users of the product.


• Fixed price products - (e.g. Broadband Plus and Broadband Premier), which offer guidelines for the amount of peak time usage that can be expected. These guidelines are based on the contribution of customers who buy the product and the average amount we expect them to use.

It’s important to understand that usage allowances on Broadband Plus and Broadband Premier represent the maximum level of usage that the account is designed for, rather than "every customer can download this much each month". We don’t expect everyone to fully use their allowance every month, and if that were to happen the network infrastructure wouldn't be able to cope. The same techniques are used by every ISP who doesn't limit themselves to selling just PAYG products. This is a factor that can lead to confusion for consumers, and that is something we want to minimise in our future product marketing as far as possible, while also recognising that we must be competitive in the market.

Of course, for the vast majority of people who don’t use up to the usage allowance every month, a shared design like this doesn't pose any problems at all. However, the nature of any product designed in this way is that there will always be a number of customers who end up with an unsustainable long term usage pattern. This may be deliberate in some cases, but more often than not it is because after choosing a product, a customer's usage habits subsequently change. For these customers there are effectively three choices:

1. Upgrade to a different PlusNet product that is more suited to the new usage requirements.
2. Moderate peak time usage, either by reducing the amount of large downloads, or by scheduling more downloads to overnight periods when demand for interactive traffic is lower.
3. Find another ISP which is more suited to the specific usage requirements of that customer.

4. PlusNet's existing product designs
The current usage allocations were started in April 2006 and reviewed in October 2006. The product guidelines were created after working out an average amount of usage per customer and projecting how we expected that to change in the future. The pricing of our products is set as per the following rough assumptions:

* Essentially a 'line rental' for a broadband connection.

Based on an assumed wholesale cost of 70p per GB, the table shows that the amount of budgeted bandwidth per product differs significantly between Broadband Plus and Broadband Premier. Broadband Plus is assigned roughly 1.5GB, whereas Broadband Premier is built for around 7GB per customer. (Both figures assume that usage is spread evenly across the peak period during the month).

5. What has happened since April 2006?
The product designs shown above worked well for a time, but there have been two major changes since we last worked out the usage allowances we offer. During Summer 2006 the nationwide upgrade to the BT IPStream Max product provided many people with speeds of up to 8Mbps. We now have nearly half of our userbase using this faster product. This has led to more bandwidth being consumed and an increase in the number of large downloads being performed by our customers - we under-estimated the affect this would have on overall usage.

The second big trend in the latter half of 2006 has been the increase in consumption of multimedia content, (e.g. video download sites and web streaming). Previously our Broadband Premier customers were the big users of these applications, but as the web has evolved many Broadband Plus customers have significantly increased their usage too. How we intend to handle this is explained below.

6. Network expansion and central capacity
We frequently review our plans for the purchase of additional capacity and this will continue in the future. The reviews focus on current and projected customer numbers and the budgeted amount of capacity being used across all of our accounts. We make future capacity purchases on this basis.

We recently announced that we have added a further BT Central pipe (in addition to the capacity supplied to our customers on the Tiscali LLU network). This was done to reduce session problems, and will also allow us to encourage and support future growth. We've also announced that we are increasing the build capacity for every Broadband Plus account, ahead of the wholesale pricing reduction due in May 2007. This is expected to address recent performance issues for time-sensitive applications on Broadband Plus (e.g. web browsing, email, gaming and Internet phone calls).

It's important to us that our customers can see what state the network is in at any point in time, and how that may impact on performance. As well as current portal features showing this, we are planning to publish a new network status report to our website. Details of this how this will work can be found in our Managing our Network Under Abnormal Load guide. The system will provide a measure of the current network status, measured against the expected design performance. In certain circumstances, we have to operate our network with higher than normal demand present, and we are keen that this is shown accurately.

As well as managing our current BT IPStream and Tiscali LLU platforms, we are also busy planning for the future using BTs new WBC (Wholesale Broadband Connect) product, as we announced in our documented Plans for 2007. WBC will be the first product to use BT's new 21st Century Network (21CN). This will provide a more efficient and scalable infrastructure than is available currently.

Our next step will be to trial the current BT Retail platform with our customers, as we intend to use this platform to deliver our WBC products. In the near future we intend to offer an optional trial of this for our PAYG customers. We'll provide more news about this soon.

7. BT IPStream vs. Wholesale Broadband Connect
Because BT Wholesale's development focus is now on WBC and 21CN, further development of IPStream is expected to end. This means that remaining technical issues are unlikely to be resolved. This includes the undiscriminating round-robin allocation of sessions, which have been one factor in recent peak time performance and session availability issues. Products using ADSL2+ (Which will provide speeds of up to 24Mbps) are also expected to only be available on 21CN-based products.

More importantly, there is now little incentive for the economics of IPStream to be improved beyond the changes that have already been announced. We are expecting that the economic and technical advantages of WBC will put service providers who remain on IPStream at a severe disadvantage.

8. What makes PlusNet different?
Customers reading this will be aware that our approach has been different to that of other ISPs. Some ISPs have grown by taking a completely unmanaged approach to selling connections, and have added capacity on demand. This is a situation we found ourselves in over two years ago and we realised it would be impossible to sustain this in the longer term. Other ISPs have applied network-wide rate limits on certain applications (usually peer to peer) to try and curb the usage which made their products unsustainable.

We think that these measures represent an unsatisfactory approach to take. Selling different products with no means of governing their differentiation can't work in the long run. Simply adding BT Central capacity on demand is extremely expensive, even when subsidised by higher monthly subscriptions. This can only lead to the provision of a loss making service, resulting in a poor service for customers using those ISPs.

Our approach to broadband traffic management is aimed at offering the fairest solution for the vast majority of customers. Sensitive real-time and interactive applications run as fast as possible, and customers can download large files during quieter periods without impacting other customers. We think it is too simplistic to merely rate limit specific types of usage dependant on the time of the day. We believe that customers prefer a system where different types of usage are dynamically assigned appropriate priorities, based on clearly defined and published network management rules.

9. The future
Of course, ours is not a static system; usage habits change, technology continues to evolve and many new bandwidth-hungry applications are becoming popular. Both our traffic management techniques and the product designs behind them will need to change to accommodate this. We firmly believe that Video-on-Demand (VoD) and products like BT Vision will continue to drive up average usage. We are making the plans now that will enable this growth to be supported.

We will continue to develop our traffic management systems with an end goal of supplying broadband connection packages that are tailored perfectly to customer requirements and which will ultimately allow people to determine themselves how their service is managed within their own bandwidth allocation. Read more about the future of traffic management.

In summary we intend to allow customers to tailor their own packages to suit specific needs, so you could configure a package for on-line gaming, or design a product for usage entirely based on web browsing and email.

Of course, we want to discuss these developments with our customers as they become a reality. We remain confident that the approach we are taking is the best way forwards for us and our customers and will ultimately set us apart from our competitors. It is clear that any ISP which has so far provided an unsustainable product will need to address that situation at some point in the near future.

Related links

Managing our Network Under Abnormal Load
Find out about our plans for the Future of Traffic Management

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