An overnight backup process that spills into working hours can easily clog up a network. This can be reduced through user education or by taking technical measures, suggests Atkinson. For example, locking down PCs to prevent users installing software will reduce the number of files that change from one day to the next.
Backup software may respect a time window and prioritise any missed files during the next run if correctly configured. For greater flexibility, look for software that will limit itself to a certain fraction of the available bandwidth during particular hours, that way it can run at full speed during quiet times, and throttle back to a trickle feed during the working day to complete the backup as soon as possible without causing disruption. This can also be implemented through QoS features.
It's important to ensure that your hardware is fast enough for the job. Can the backup server do virus checking and compression in real time? Can it write to tape at least as fast as the data is arriving? The network isn't the bottleneck if you're using a 2Mbps link but the drive is only running at 1Mbps, Atkinson says.
Other processes can occur at the wrong time. Atkinson mentions a situation where Dell's OpenManage systems management tool had been configured to discover all devices at 10am each day, flooding the network and slowing real work to a crawl. There was nothing wrong with the software, he says, just the way it was configured.
Something similar can happen with automatic updates to antivirus and other software if too many PCs try to update at the same time. For example, the plan might be to update branch office computers primarily from a local server, with a head office server (or even the vendor's web site) as the secondary. It's easy to clog a WAN link if the branch server is down and all the PCs in the building try to update simultaneously.
"You need to be a little bit careful about the way you configure things," Hayes says, adding that organisations with international networks need to pay particular attention to timing, especially when moving bulk data between regions, as one area's quiet time can coincide with the other's peak.
8. Citrix/thin client
Webifying enterprise applications may make for a more consistent user interface overall, but it can also degrade network performance. According to Hayes, some analysts report it can consume five times the bandwidth while delivering only one-quarter the performance.
One solution is to use Citrix-based thin client technology to reduce the amount of data flowing through the network, says Phil Osborne, senior consultant, enterprise, at Citrix Systems Australia. He says it even makes sense to run the browser on central servers -- "that's a trick we see a lot of companies doing" -- otherwise the application may run more slowly than the previous client/server architecture.
"Just don't move the traffic around the LAN or WAN unless there is a real need to do so," says Osborne. For example, large files attached to e-mails remain inside the data centre unless they are explicitly copied to a PC. He points to Flight Centre as an example, where branches have been equipped with Wyse terminals to access centralised Citrix servers over relatively low-bandwidth connections. Print traffic can put a significant load on a network in some environments, says Osborne, but the combination of Citrix's recent print drivers and products such as Exceed, Spinifex and ThinPrint reduce the traffic and increase printing speeds.
Citrix offers software that supports streaming video to a thin client, and has acquired a company with technology that will enable the use of VoIP softphones with thin clients.
It's a question of looking at the data that's being sent, and identifying a smarter way of sending it, Osborne says.
Switching to Citrix isn't the end of the story. Gibb points out that various tweaks -- such as tuning the caching of large bitmaps or the appropriate segmentation of packets or frames at the data link level -- may make an appreciable difference to overall performance.
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