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F E A T U R E

Bandwidth Regulators

May 28, 2001
By Lori MacVittie

Nortel Networks Content Networking Business, Alteon AceDirector 4

AceDirector 4 has so many features it's difficult to know where to start. This 2U form factor device is primarily a load balancer but integrates bandwidth management as well for a well-rounded Internet appliance. The AceDirector 4, which can act on Layer 2 or 3, inserted into our network with ease. Configuration and management is available through a CLI via console or telnet, as well as a Web-based GUI.

The AceDirector 4 is trustworthy. When we said 11 megabits is all the HTTP traffic that is allowed, that's all it got. What we didn't like was how difficult it was for a "contract" to borrow unutilized bandwidth from other "contracts" if necessary, a service offered by both QoS Control for e-Business and QoSWorks 10000. Most products allow you to set a limit and then provide a burst amount, effectively allowing the class of traffic to borrow bandwidth from other classes if the class becomes oversubscribed and bandwidth is available. With the AD4 this task is difficult, because hard limits must be set for each contract and the total of all hard limits cannot exceed the total link. There is no easy way to allow a contract to borrow from another contract.

AceDirector 4 is very well suited to a service provider environment where strict adherence to bandwidth limits is required to meet SLAs and subscription limits, but it might fall short of effectively utilizing bandwidth in a corporate-class environment. Borrowing can be accomplished, but it is not as effective nor easy to configure as the solutions from Lightspeed and Sitara.

Queue lengths can be modified, something we were unable to do with QosWorks, in order to tweak performance. We didn't need to modify them, as the AceDirector 4 default queue lengths showed us great response times for interactive traffic and reduced the average jitter rate for RealAudio traffic to .064 milliseconds.

AceDirector 4 implements a weighted fair-queuing algorithm and can manage traffic from 250 kilobits per second up to 1 Gigabit. Unlike its competitors, traffic can be classed by port, VLAN, VIP (virtual IP address), URL, cookies or port filters.

Alteon AceDirector 4, Nortel Networks Content Networking Business, $20,999, (888) 258-3661, (408) 360-5500; fax (408) 360-5501. www.alteonwebsystems.com or sales@alteon.com