From the designation 10GBase-ER, the following can be seen: 10G stands for 10 Gigabit Ethernet, Base for baseband, the "ER" stands for "Extended Reach", which refers to the wavelength of the duplex monomode fiber at 1,550 nm. 10GBase-ER operates with a DFB laser and has a bridgeable distance. The 10GBase-ER interface uses 64B66B coding. The effective data rate is 10 Gbit/s, and the 64B66B coding gives a resulting baud rate of 10.3125 Gbit/s. LCconnectors and SC connectors in duplex design are used as FO connectors.
In terms of nomenclature, the 10GBase-ER interface is a 10GbE interface for local area networks; it is also suitable for wide area networks and city networks. The physical layer corresponds to that of 10GBase-EW. The bridgeable distance is 40 km.