Expert Witness

Expert Witness

Adrian Sunderland, CTO Griffin Internet

The average amount of bandwidth that a typical broadband end-user consumes has been steadily rising month on month since broadband first became available in the UK. This is largely due to the growth in streaming multimedia applications, rich media web sites and peer-to-peer file sharing.

In the last couple of years this has begun to cause real economic and capacity planning issues for service providers. The consumer-focussed providers have been worst hit and have responded by creating various capped and usage-billed services so that those customers using the most bandwidth pay the most money. In addition some providers have resorted to various traffic engineering and traffic management techniques, with differing degrees of success, to try and squeeze as many customers onto their network as possible.

Most readers of this magazine will be supplying business customers and probably don’t feel much affinity with the problems experienced by consumers

and their providers. However, as many providers supply both consumers and businesses then it is inevitable that the growth in bandwidth consumption and the tendency of providers to ‘manage’ Internet traffic will result in more congestion.

It isn’t that traffic management techniques such as deep packet inspection automatically cause congestion it is just that when dealing with a base of mixed consumer and business customers that is often the effect. This doesn’t really cause the consumer too many problems – a bit of congestion and packet loss will go unnoticed when you are browsing web sites, replying to email or downloading files. However congestion can be disastrous for some real-time business applications.

I believe that the interests of business users are best served by providing business-grade services with total separation from consumer users and consumer services. However as many organisations do little to control the software that employees install on their PCs, particularly in organisations that use a high proportion of portable computers it is often the case that a large amount of an organisation’s bandwidth is being consumed by non-business applications.

Deep packet inspection and traffic shaping can be used to ensure that non-business traffic such as video streaming sites, P2P file sharing, social networking sites cannot cause congestion and starve important business applications of bandwidth. This is more important than ever now that so many businesses rely on broadband to carry delay-sensitive traffic like Voice over IP, Citrix and MS Terminal Services to smaller branch offices and home workers.

Deep packet inspection is a technique for managing traffic on a network-wide basis with the aim of preventing congestion. If the service provider network is not congested but an individual subscriber broadband line is, then it is more appropriate to use QoS to prioritise traffic streams between the service provider and the end-user. This is particularly true when dealing with realtime traffic such as VoIP. The ability to support per-subscriber QoS profiles should really be considered a must have when choosing a supplier of business-grade broadband.

I would be interested in hearing from anyone with experience of business applications that don’t work well with your existing broadband provider. I would also be interested in hearing from readers with suggestions for topics that I could cover in future in this column.

Deep packet inspection (DPI) is a form of computer network packet filtering that examines the data and/or header part of a packet as it passes an inspection point, searching for nonprotocol compliance, viruses, spam, intrusions or predefined criteria to decide if the packet can pass or if it needs to be routed to a different destination, or for the purpose of collecting statistical information. It is also called Content Inspection or Content Processing. This is in contrast to shallow packet inspection (usually called just packet inspection) which just checks the header portion of a packet.
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