Asymptotic bandwidth

　　The asymptotic bandwidth for a network is the measure of useful throughput, when the packet size approaches infinity.

　　Asymptotic bandwidths are usually estimated by sending a number of very large messages through the network, measuring the end-to-end throughput. As other bandwidths, the asymptotic bandwidth is measured in multiples of bits/second, e.g. megabits per second, etc.
Related:
xfp and sfp differences
sfp vs xfp
http://sopto10gmodule.wordpress.com/2013/04/25/analysis-by-the-optical-fiber-cold-into-in-theory/