Cisco has issued a recall for the fan tray units of its new Catalyst 4500 LAN switches after internal testing determined that they can short circuit and render the switch inoperable.The recall was issued Dec. 10 and affects roughly 3,000 switches shipped to date, a Cisco spokesman says. The spokesman says no customers have been impacted by the short circuiting situation."As part of the manufacturing process, the switches go through testing. We discovered that there were a handful of units that did fail," the spokesman says. "We were fortunate to catch (this) internally before it began to affect customers."The short circuiting causes a fan freeze failure, potentially causing damage to the switch's backplane, according to the spokesman. Though no customers have experienced the problem, the spokesman says customers may have to schedule network downtime to deactivate the 4500 switch and replace the affected fan trays if the fan tray units are not hot-swappable.Cisco will provide new replacement fan trays free-of-charge as part of the Catalyst 4500 warranty. The spokesman says the recall will not have a material financial impact on Cisco but observers say it could cause a short-term slowdown in sales of the 4500, which is Cisco's second largest line switches.Sources say the list price for the fan tray is $395 and that the replacement fans will cost $100 to $150 per unit. The Cisco spokesman would not confirm these figures.The Catalyst 4500 line, which includes the 4503, 4506, and 4507R, was introduced last September. The switch line is optimized for network operators and service providers offering metro area business services aggregation and subscriber access, as well as wiring closet applications for large enterprises.