With the frame format and other Ethernet Layer 2 specifications compatible with previous standards, 10GbE can provide increase bandwidth needs that interoperable with existing network infrastructure.

A major conceptual change for Ethernet is emerging with 10GbE. Ethernet is traditionally thought of as a LAN technology but 10GbE physical layer standards allow both an extension in distance (to 40 km over single mode fiber) and compatibility with SONET/SDH networks. Operation at 40 km distance makes 10GigE a viable MAN technology. Compatibility with SONET/SDH networks operating up to OC-192 speeds (9.584640 Gps) make 10GbE a viable WAN technology. 10GbE may also compete with ATM for certain applications

To summarize, how does 10GbE compare to other varieties of Ethernet?

• Frame format is the same, allowing interoperability between all varieties of legacy, fast, gigabit, and 10 Gigabit, with no re-framing or protocol conversions
• Bit time is now 0.1 nanoseconds; all other time variables scale accordingly
• Since only full-duplex fiber connections are used, CSMA/CD is not necessary
• The IEEE 802.3 sublayers within OSI layers 1 and 2 are mostly preserved, with a few additions to accommodate 40km fiber links and interoperability with SONET/SDH technologies
• Flexible, efficient, reliable, relatively-low cost end to end Ethernet networks become possible;
• TCP/IP can run over LANs, MANs, and WANs with ONE Layer 2 Transport Method.

The basic standard governing CSMA/CD is IEEE 802.3. An IEEE 802.3 supplement, entitled 802.3ae, governs the 10GBASE family. As is typical for new technologies, a variety of implementations are being considered, including:

• 10GBASE-SR – intended for short distances over already-installed multimode fiber, supports a range between 26 m to 82 m
• 10GBASE-LX4 – Uses WDM, supports 240 m to 300 m over already-installed multimode fiber and 10 km over single-mode fiber
• 10GBASE-LR and 10GBASE-ER – Support 10 km and 40 km over single-mode fiber
• 10GBASE-SW, 10GBASE-LW, and 10GBASE-EW – intended to work with OC-192/STM SONET/SDH WAN equipment.

The IEEE 802.3ae Task force and the 10 Gigabit Ethernet Alliance (10 GEA) are working to standardize these emerging technologies.

10 Gbps Ethernet (IEEE 802.3ae) was standardized in June 2002. It is a full duplex protocol that uses only optic fiber as a transmission medium. The maximum transmission distances depend on the type of fiber being used. When using single mode fiber as the transmission medium, the maximum transmission distance is 40 kilometers (25 miles). Some discussions between IEEE members have begun that suggest the possibility of standards for 40, 80, and even 100 Gbps Ethernet.

The maximum Ethernet packet (a frame) is 1500 bytes. This has been the standard since Ethernet was created. Large files could be moved over the network more efficiently if a larger amount of data could be carried in each frame. The reason for this is that it takes time for computers to generate and to process Ethernet headers and trailers. Larger frames mean that fewer headers and trailers would have to be generated by the transmitter and processed by the receiver. Wide Area Networks (WANs) that use fiber as their transmission medium routinely transmit large data packets.

It is likely that the use Jumbo Ethernet frames will be one of the next innovations Ethernet. The proposed upper limit for the amount of data carried in a Jumbo frame is about 9,000 bytes. Jumbo frames are not currently a part of the new IEEE 802.3ae standard. However, it is very likely that some vendors of Ethernet networking equipment will allow Jumbo frames to be carried on Ethernet networks built using only their equipment. This may force the IEEE 802.3 committee to make support for larger frame sizes an option in new multigigabit standards.

Web Links 10 Gigabit Ethernet http://www.cisco.com/en/US/tech/tk389/ tk214/tk771/ tech_protocol_home.html