Keeping in
touch with the very Ethernet tradition, the group set the goal of providing a significant
increase in performance while minimizing equipment, operation, and maintenance costs,
aiming in fact at the development of Ethernet PON system specifications.
Ethernet PON (EPON) is a PON-based network that carries subscriber data encapsulated
in native Ethernet frames, as defined by the IEEE 802.3 standard [2], using 8B10B
line coding (8 data bits of PCS layer data encoded into 10 line bits at the PHY layer) and
operating at the standard Ethernet speed of 1 Gbps (PCS layer) / 1.25 Gbps (PHY layer).
Where possible, EPON uses the existing IEEE 802.3 specification, including application
of the existing 802.3 full-duplex media access control (MAC) as defined in 1000BASE-X
specifications with PON specific extensions at the RS and PCS layers.
The IEEE 802 group has traditionally focused on enterprise data communication
technologies. In EPONs, the main emphasis is on preserving the architectural model
of Ethernet, and thus no explicit framing structure exists. Ethernet frames are transmitted
in bursts, with a standard inter frame gap (IFG) inserted between individual
frames.
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