As communication standards have evolved, the IEEE, has developed a level of standards that are used globally by manufactures of networking components. Periphery components, like the glc sx mm e 1000base Small form factor gbic's.
IEEE standards can come about from the development of a single developer such as Cisco. This occurs frequently in other networking developments such as the "Token Rings" technology from IBM. Occasionally the standards arise from a group of vendors rather than one individually.
The purpose of generalizing the specifications of a standard is to maximize the inter-changeability of components. If upgrading SFP's one should not have to worry about whether the 1000base sx component is made by cisco or is Avaya's 108873241. So while the router might require a specific medium for transmission the IEEE standard generalizes this requirement.
These different standards go through a suggested stage where various aspects of the proposed standards are reviewed. The standards for the 10000base form factor have been agreed upon and have been published by the ieee. The GLC SX MM is Cisco's version of the 1000base sx small form factor pluggable GBIC. The GLC SX MM is the sfp module product number that represents a module with a class 1 laser of 850nm.
This particular sfp is therefore interchangeable with any other manufacturer's SFP module with a class 1 laser of 850nm. In addition, the glc sx mm e can also be an interchangeable SFP with a wide spectrum of uses. For example as a single mode and multi-mode SFP it can also be interchangeable with one that is merely a single mode optic transceiver.
Original Equipment Manufacturer's components can interchange with the unit provided it meets ieee's networking standards. Using an OEM alternative can lower the cost of network upkeep by as much as forty percent. This strategy is not only available but is sometimes demanded for larger municipal networks.
Source: ezinearticles.com