D-Link DGS-1248T network switch

D-Link has been banging on about its energy-saving ‘Green Ethernet’ technology for quite some time, but it has taken a while for it to be incorporated into products.

Low-end consumer switches were the first and now it’s being added to D-Link’s business switches, starting with the Gigabit Web Smart Switch range.

The technology involved can cut energy consumption in several ways. For example, instead of running all the ports in a switch at full power (to cope with the maximum cable length of 100m), the amount used can be adjusted on a port by port basis, according to the length of cable detected. Likewise the new D-Link switches can put ports into a low-power standby mode if nothing is found to be connected or the device attached is turned off.

Actual savings will depend on network configuration and usage, but D-Link reckons the technology will be able to reduce power consumption by almost 50 per cent on a typical small-business Lan. On top of this, new 90nm silicon technology is used on the switches to further minimise energy use.

Other claimed advantages of the D-Link technology are lower heat emissions and longer product life, with three Web Smart switches now available with Green Ethernet on board. The smallest and cheapest is the 16-port DGS-1216T at £104.33 ex Vat, followed by the 24-port DGS-1224T at £156.51 ex Vat and the range-topping 48-port DGS-1248T we were sent for review. All are 1U 19in rackmount devices housed in robust metal cases and equipped with a single integrated AC power supply at the rear.

The port connectors are all at the front, together with the usual tell-tale LEDs. On ours that meant 48 auto-sensing 10/100/1,000Mbits/sec UTP ports, four of which can be mapped to a set of SFP connectors to support fibre uplinks using plug-in adapters. The smaller models only have two of the SFP slots and are both fanless, further saving on power requirements. However, that’s not possible on the DGS-1248T, which needs three fans to cope with the heat generated by so many Gigabit ports. The end result is pretty noisy and this model is best located in a machine room or sound-proof cabinet rather than an open-plan office.

A built-in web-based interface is used to manage the Web Smart Switch, with a custom management console for larger deployments and general SNMP support also provided. We found the web interface slow but effective and very straightforward with many of the options, including the power-saving feature, enabled by default.

Other options worth mentioning include support for port trunking ­ to link switches together and for high-speed server connections ­ plus the ability to configure up to 256 VLans. Similarly you get built-in support for up to four 802.1p QoS (Quality of Service) queues per port, to prioritise different types of traffic, together with a variety of security facilities including 802.1x access control and protection against packet flooding attacks.

At a just over £7 per port, the DGS-1248T is good value, especially given that it’s an all-Gigabit solution. Add in the extra functionality over and above the basic L2 switching capabilities and it becomes even more attractive, with the Green Ethernet technology yet another feather in the cap of this innovative small-business network switch.

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