There doesn't seem to be much information about the 2908...I wonder why?
Are there any disadvantages to using a 2908 instead of 2912/2924 besides a lower port count? Are they basically the same otherwise?
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If you're thinking about buying a 2900XL instead of the 2950 Series to save money, check the following link. The last four switch in the table WILL NOT be good for your CCNA studies because it doesn't support Trunking, and they CAN NOT be upgraded...don't be fooled. Notice the 2924 is very confusing, 2924XL, 2924C-XL,2924XL-EN,2924XL-A, etc....
http://www.cisco.com/en/US/docs/switches/lan/catalyst2900xl_3500xl/releasesa4/eesoftconfig/mascovr.html