1. Do I have to really use Cisco branded trancievers? I've seen non-Cisco 1000BASE-SX SFP on ebay for one-tenth the cost. Bearing in mind that, yes the quality may or may not be the same.
According to the SG300's Quick Start Guide "SFP ports are compatible with Cisco modules MGBT1, MGBSX1, MGBLH1, MGBLX1, MGBBX1, MFELX1, MFEFX1, and MFEBX1, as well as other brands of modules."
2. Is MGBSX1 the way to go? Switches are in different rooms so distance is not an issue, my choice was based on cost for trancievers and media.
Choose the type of SFP based upon the links length and available fiber type. The Small Business SFP Data Sheet provides the information you need. The MGBSX1 is probably a good choice, low cost, up to 550 meter link length over multimode fiber.
3. The SFP ports are rated at only gigabit, but I've seen various higher numbers quoted. Is that a limitation of the switch itself, the protocol being used or the transmission media?
Each switch is designed to support specific port speeds, based upon the switches designed application in the network. Optical Transceiver Modules do not support different speeds (as do many electrical ports). Instead, given the switch port is compatible, the transceiver module can be swapped out to change the speed. SFP style modules are available at 100Mbps and 1Gpbs; SFP+ modules for 10Gbps; higher speeds have new form factors. You can view many of the styles of Optical Modules on the Cisco Transceiver webpage.
Good luck!
