Many data centre managers that need to monitor new 10G network segments can't currently justify the significant investment in new monitoring devices, but high density aggregation filtering systems make it possible to get the job done using 1G monitoring tools. For a 10G tool, such as an analyser, prices often start at $50,000, while the annual support contract can add another 15%.

So the investment for an organisation that has, say, five geographically dispersed data centres, each equipped with five analysis tools, can run to over $1 million in capital costs and nearly $200,000 in annual support fees. Given this challenge, many organisations are finding ways to use existing 1G tools to monitor both the 1G infrastructure as well as the 10G links. What makes this possible is the advancement of aggregation and filtering technology.

Devices supporting aggregation and filtering have been available for some time, but they are typically limited to 1U units offering 24 to 36 ports per chassis. Therefore it has been necessary to "trunk," or daisy-chain, multiple units together to achieve the optimal port density to ensure the required level of monitoring. This approach brings with it unnecessary cost and management issues that are now mitigated by single chassis aggregation and filtering systems with much higher port densities and enterprise-class designs.

As a rule, all devices offering aggregation and filtering allow users to combine multiple network links, pare the stream down to only the necessary data and direct the resulting traffic to a specified tool or series of tools. Filtering the data to only the required information – such as a range of IP addresses or virtual LANs – prevents the likelihood of oversubscription where packet loss occurs.

With recent advancements, single chassis featuring up to 144 ports of combined aggregation, filtering and switching capability are now available, which is up to four times the maximum port count generally achievable in the market.

So why should data centre managers consider a high-density unit? To begin with, it eliminates the need to trunk multiple devices together, which introduces the potential of multiple points of failure in the monitoring process. A second issue is the need to manage multiple platforms – keeping tabs on arrays of individual daisy-chained boxes is time consuming. Managing bandwidth is also critical. A trunked architecture makes it more challenging for managers to oversee aggregated bandwidth – between SPANs and tools, as well as across the chassis. If this combined bandwidth is not well managed, oversubscription will occur and packets will be dropped.

A single high density chassis, with the combined switching, aggregation and filtering capability, negates all the problems that come with a trunked approach. It also offers IT managers another benefit – a highly scalable platform from which it is practical to monitor a 10G network using the enterprise's existing 1G tools.