10Gb Ethernet: Meeting the switching challenge

Ethernet and Gigabit Ethernet technologies have brought increased capacities, greater efficiencies, enhanced productivity and a host of other benefits to corporate networks over the past two decades. Now, the concept of 10Gb Ethernet is set to expand these horizons even further and allow the vision of native end-to-end Ethernet networks to be implemented.

Gary Boniface, CSO manager at 3Com SA, examines the 10Gb Ethernet revolution and looks at the features of intelligent switching technologies that are needed to keep pace with today`s runaway demand for bandwidth.

Ethernet accounts for over 95% of the networking switches sold today. Ethernet, Fast Ethernet, and Gigabit Ethernet has gained worldwide acceptance as an enterprise networking infrastructure technology because of its considerable advantages in terms of scalability, simplicity and speed.

Now, the industry stands on the threshold of a new challenge: How to meet the need for almost unlimited bandwidth, while keeping the cost of networking within bounds. The answer is the proposed 10Gb Ethernet (10GbE) standard.

An extension of the existing IEEE 802.3 Ethernet standards, 10GbE has the potential not only to support huge payloads, but also to unify systems over a single architecture.

With 10GbE, enterprise managers will be able to leverage their existing Ethernet investment while significantly increasing network backbone performance. They will have next-generation speed at their disposal, allowing them to scale everything up without having to change topologies or equipment.

This is likely to be an increasingly vital advantage as LAN bandwidth requirements continue to soar with the increasing adoption of bandwidth-hungry applications such as video streaming.

The IEEE 10GbE taskforce does not expect to publish its fully approved standards until early 2002, but when it does vendors will roll-out network solutions with staggering increases in:

a.       The number of network connections.

b.       Connection speed - as LANs scale up and dial-up users move to broadband, with even higher network speeds needed for aggregating these increasingly higher connection speeds.

c.       Bandwidth-intensive applications such as broadcast-quality video, VoIP and other new-generation applications.

d.       Web hosting and application service provision.

As this happens, the network will become the foundation for new business models and e-commerce initiatives that converge voice, data and video applications.

All three of these forms of information have significantly challenging networking requirements:

a.       Video requires a large amount of bandwidth, with consistency and low latency.

b.       Voice requires a relatively small amount of bandwidth, with consistency and low latency.

c.       Data can require very large to very small amounts of bandwidth, and often does not have latency constraints.

In addition, e-mail - used extensively within most organisations and to communicate with suppliers, partners and customers - requires low bandwidth, and does not have latency requirements as it is typically a background task.

The mix of bandwidth and latency required by these widely varying types of information realistically means prioritisation in networking equipment is a mandatory requirement if the network is to be the "glue that ties these applications together".

Without prioritisation, networks can at best be "common denominators" in terms of providing basic networking services.

In addition to the ability to prioritise traffic by applications, a critical feature to look at in a networking platform is how the prioritisation is accomplished.

Most Ethernet network platforms based on conventional network switches are able to perform only what is referred to as Strict Priority Queuing. Simply stated, this means that at any given time, they will always forward the highest priority packet.

A problem with Strict Priority Queuing is that lower priority traffic could be completely blocked by higher priority traffic. Weighted Round Robin addresses this problem by servicing all the traffic queues with priority given to the higher priority queues. This means that under most circumstances, higher priority traffic will be given precedence over lower priority traffic, but in the event of high priority traffic exceeding the link capacity, lower priority traffic is not blocked completely.

Users looking to implement application-aware networking solutions, should look for a switched network platform that implements "layer-4" switching technology.

Often described as "intelligent switches", Layer-4 switches incorporate a form of "traffic prioritisation" that included both strict and weighted-fair-queuing methodologies.

These switches have built-in intelligence and are able to recognise an application. They are able to prioritise that application`s traffic to best serve the user`s needs.

What is the "layer" concept increasingly used in networking today? The seven layer concept was devised by the International Standards Organisation when it standardised the Open Systems Interconnection (OSI) model.

This model has become the foundation for the development of all information technology products, including all networking products.

The OSI model set out to identify the role of each of the "layers", and to build a framework that allows the information necessary for one layer to be isolated from the information necessary for a different layer.

The highest layer (layer 7) is the application layer. Applications are typically implemented in software, and would include e-mail, CAD, word processing, spreadsheet, etc.

Layer 1 is the physical layer. An example of this is the twisted pair cabling and associated driver and receiver hardware/ software necessary to implement Ethernet. Layer 1 is associated with connecting one end-station to another.

Previously, networking equipment dealt only with layers 1, 2, and 3. The support of layer-4 in a networking device allows the Application layer protocol (identified by the layer 4 port number) to be used to prioritise the network traffic end-to-end.

Application-aware switching implementations have brought Layer-4 technology to the forefront of the networking industry, and should be considered as a tool by any enterprise deploying networking technologies that are needed to take them into the future.