The 27xx series is a lower level access switch that was not built to handle spanning tree calculations.  One option is to upgrade the 27xx switches to the newer 28xx series that has Spanning Tree Protocol Features.   I hope this helps,
Hi All, I have many Power Connect 2748 switches throughout my network.They all have the latest and greatest Firmware version 1.0.0.33 A00  I am aware that people load other firmware on residential grade routers. (Eg. netgear, old linksys routers etc).I was just wondering, if anyone knows if it's possible to load some other dell firmware onto these switches? Specifically some firmware capable of running spanning-tree. I work in an environment where people accidentally plug in both ends of a cable into ports on a wall. Thanks/Nick 
Firmware for Power Connect 2748