Physical medium dependent
 | It has been suggested that this article be merged into Ethernet physical layer, Talk:Physical Media Dependent#Proposed_merge_into_Ethernet_physical_layer and Gareth8118. (Discuss) Proposed since February 2007. |
Physical Medium Dependent sublayers or PMDs were defined by the IEEE 802.3ae task force in 2002. These sublayers define physical layer specifications in 10 Gigabit Ethernet transmissions. It is responsible for the transmission and reception of individual bits on a physical medium. These responsibilities encompass bit timing, signal encoding, interacting with the physical medium, and the cable or wire itself
The Ethernet PMD sublayer is part of the Ethernet PHY layer. The hierarchy is as follows:
Data Link Layer (Layer 2)
LLC (Logical Link Control Sublayer)
MAC (Media Access Control Sublayer)
PHY Layer (Layer 1)
PCS (Physical Coding Sublayer)
This sublayer performs auto-negotiation and coding such as 8B/10B
PMD (Physical Medium Dependent Sublayer)
This sublayer consists of a transceiver for the physical medium
The Physical Medium Dependent Sublayers (PMDs)
- 10GBASE-E
- has been defined for single mode fiber operations only. It operates in the 1550 nm band allowing for distances of up to 40 km to be reached.
- 10GBASE-L
- was also defined for single mode fiber operations, uses the 1300 nm band allowing it to reach up to 10 km.
- 10GBASE-S
- was defined for use in multimode fiber and ultimately costs less than the other 10GbE standards. It uses 850 nm lasers and only reaches distances ranging between 26 to 82 metres on older fiber technology. In newer optimized multimode fibers (a.k.a OM3) it can reach up to 300 m.
- 10GBASE-LX4
- uses four lasers that each transmit at 3.125 Gbit/s. The receiver is arranged in a wavelength-division multiplexing manner. On legacy FDDI multimode fiber it can reach up to 300 m while on single mode fiber it can reach up to 10 km.
After these specifications have been laid out they are then placed in to LAN and WAN specifications using three different Physical Coding Sublayer standards.
References
- Barbieri, Alessandro. “10 GbE and Its X Factors.” Packet: Cisco Systems Users Magazine Third Quarter 2005 Vol. 17, No. 3: 25 – 28.