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Long-distance, point-to-point optical Ethernet - The technical objective is to standardize operation of 1,000M bit/sec (1000BaseX) Ethernet over a single fiber (instead of a fiber pair) at a distance greater than or equal to 6.2 miles. This new fiber-optic physical layer interface could be used to provide lower cost, single-mode optical interfaces, using half the amount of fiber currently required for Gigabit Ethernet at distances twice that currently specified by the standards. State-of-the-art 1300nm and 1550nm single-mode optics will be leveraged to support this work. This will be a relatively minor enhancement to existing Ethernet, using technology that is generally considered to be low risk. This kind of connection would be most applicable to high-speed corporate networks.
Can ethernet go end to end?
Voice-grade copper Ethernet - The technical objective is to support point-to-point distances greater than or equal to 2,500 feet at speeds greater than or equal to 10M bit/sec. Technical presentations have shown operation at speeds near 50M bit/sec for shorter distances with operation at lower than 10M bit/sec speeds at much longer distances. While some study group members want to just "steal" the physical layer specification developed for ANSI T1E1.4 very-high bit rate DSL, there are also other proposals that will meet this requirement. This activity will likely require more work than long-distance optical fiber, but in the true spirit of Ethernet it will "borrow" from past work.
Passive optical Ethernet - Perhaps the most aggressive and controversial of the three topologies being considered, the Ethernet Passive Optical Network (EPON) technical objective is to develop an 802.3 compatible physical layer interface for operation at 1000M bit/sec, at distances greater than or equal to 6.2 miles, with support for at least 16 or more end points, in a shared, point-to-multipoint topology. EPON expects to borrow heavily from work already done within the post, telegraph and telephone administration-sponsored Full Service Access Network (FSAN) consortium. A passive optical network (PON) uses a single fiber from the central-office head end (or other active location) to service 16 to 32 end points. The optical signal would be split by one or more "passive" splitters mounted midstream in the network. In this topology, any end point could "receive" downstream traffic from the head end at up to the full 1,000M bit/sec, but would have to share the "upstream" bandwidth with up to 32 other nodes, thus limiting its share to about 30M bit/sec. The PON architecture has inherent advantages in that less fiber is required to service more users, plus power is not required in manholes, on poles, or at the curb. PONs may also have a lower-cost electronics structure, however, given the still declining cost of very inexpensive Ethernet switches, it is not entirely clear that this will continue to be the case.
The standards effort is focusing on three areas:
 
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Can ethernet go end to end?
Unfortunately, unlike the ATM PONs defined in FSAN, Ethernet operation over point-to-multipoint networks is currently undefined. Architecturally, Ethernet interfaces today expect the underlying network to be based on either point-to-point links or a shared peer-to-peer topology. Without more work, the EPON will "break" certain behaviors that higher layer protocols such as IEEE 802.1 bridging and others expect. Thus, it is expected that more work will be required to define the EPON than the prior two.
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