IEEE 802.3和以太网(10)

IEEE 802.3 架构图解,包括10M,100M,1G,10G。

called comma /K/ enables the XAUI receiver to attain frame alignment on the incoming bit stream. Each laneadjusts for proper alignment to the /K/ whenever it appears. However, each serial transmission lane operatesindependently and can often come out of alignment with respect to one another. As shown in Figure 3, lanealignment is accomplished by use of a control word defined for alignment, referred to as /A/. The XAUI lineprotocol defines specific times during the IPG when an /A/ word should be passed on all four lanessimultaneously. The receiving connection uses these words to correct for lane-to-lane skew common in mostconnections. The XAUI interface can lane align with up to 40bits (12.8ns) of skew between lanes, allowing for

significant flexibility in board design.Furthermore, XAUI compensates for differences in clock domains that often exist between each side of the link.By monitoring the difference between incoming and outgoing data rates, each XAUI connection can add ordelete specific control words in the IPG, referred to as /R/ to balance the data rate at each connection withouteffecting lane disparity.XAUI interoperabilityThe 10 Gigabit Ethernet Alliance formed a working group to examine interoperability between different vendors’XAUI implementation. This group worked in conjunction with the 10 Gigabit Ethernet Consortium to define thetest methodology and environment under which interoperability testing would be performed. The 10 GigabitEthernet Consortium, which will be responsible for performing interoperability testing between different vendors’XAUI implementation, has adopted the work completed by this group.Multiple vendors have demonstrated XAUI interoperability. All devices tested were designed to the IEEE802.3ae pecification. Each vendor has demonstrated bit error rates of 10-12 over PC board traces of 50 cmlength, demonstrating therobustness of the technology and completeness of the standard. The basic nature of XAUI enables it to bescaleable, which will provide users with a future upgrade path to extend the life of their systems. For moreinformation on XAUI Interoperability testing, please visit the 10 Gigabit Ethernet Consortium athttp://www.iol.unh.edu/consortiums/10gec.The 10 Gigabit Attachment Unit Interface, “XAUI”, is a technical innovation that dramatically improves andsimplifies the routing of electrical interconnections. It helps to overcome the length limitation associated with theXGMII, which provides full duplex operation at a rate of 10 Gb/s between the Ethernet MAC and PHY layers. Byextending the physical separation between the MAC and PHY, the interface allows for fan-out on multi-port linecards or connections to other cards within the system chassis. In addition, the self-managed interface helps toovercome associated clocking issues, which leads to a more easily implemented solution.h) 10 Gigabit Sixteen-Bit Interface (XSBI). The XSBI is provided as a physical instantiation of thePMA service interface for 10GBASE-R and 10GBASE-W PHYs. While conformance withimplementation of this interface is not strictly necessary to ensure communication, it is recommended,

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