Three recently released high-density Gigabit Ethernet modules for Alcatel’s 7000 and 8000 series OmniSwitch chassis-based switches are designed to give users relatively low-cost access to Gigabit Ethernet for applications that don’t require wirespeed connections.

The modules triple the previous Gigabit port densities available on the 7700 LAN switch and the 8800 core switch, with prices ranging from US$191 per port for copper to US$670 per port for fibre. The catch is that the modules have oversubscription rates of 2:1 and 4:1, meaning the backplanes can’t support full Gigabit throughput on all ports at once.

A number of vendors, including Cisco and Foundry, have introduced oversubscribed Gigabit Ethernet modules of late, noted Joshua Johnson, an analyst with Synergy Research.

“There’s nothing wrong with oversubscription, because it’s suitable for some applications and can save companies money,” he said.

For example, a group of office users might benefit from Gigabit Ethernet speeds, but not require consistent wirespeed access, Johnson explained. A server, on the other hand, might require a wirespeed link.

Oversubscribed modules can even be used in the backbone network to provide redundancy without an increase in network capacity, noted Brian Witt, director of product marketing for Alcatel’s network infrastructure unit.

One of the three modules, a fibre-based unit for the 8800, has 24 10/100/1,000Mbps ports and an oversubscription rate of 2:1 at a cost of US$15,995. “This lets you increase that redundancy at a more attractive price,” Witt noted. “At 2:1 it fits in the space where you wanted higher redundancy, but didn’t necessarily want higher capacity.”

The second module, also designed for the 8800, has 24 10/100/1,000Mbps copper ports with an oversubscription rate of 4:1 at a price of US$9,995.

The third module, built for the 7000 series, has 12 ports of 10/100/1,000Mbps copper with a 4:1 oversubscription rate at a cost of US$2,295.