IEEE P802.3ba draft has specified a single architecture for both 100G and 40G Ethernet. Other than increase in data rates to 100G and 40G, there will be no other change at the MAC layer, which means characterstics such as frame size and format, full duplex operation will be the same as in the previous architecture.
A PHY device connects MAC layer to the media. This device has a PMD, PMA and a PCS sub layer. PCS or physical coding sublayer is responsible for encoding and decoding of data bits into code groups and vice-versa from PMA. It also ensures clock transition density along with transportation of control signals and frame delineation. Also PCS uses the same coding scheme 64B/66B as used in lOG. PMA (Physical Medium Attachment) sub layer performs functions such as reception, trnamission, clock recovery and connects PCS with PMD sublayer. The draft also defines a common physical interface PPI (Parallel Physical Interface) for both 40G and 100G with the only difference being the number of lanes supported. .
Each lane in PPI operates at 10 gigabit per second, so incase of 40G, there will be four transmit and four receive lanes, similarly for 100G there will be 10 transmit lanes and a smaller number of recieve lanes of 10 gigabits per second. The final version of the standard is expected by 2010.
The long talked about technology PLC or Power line communicaČtion has finally become a reality.
As the name shows, PLC technology uses electric power lines for transmitting digital data. Since electric voltage and data signals waves operate at different frequences, there is no interference between them. This technology uses Wavelet-OFDM modulation and the maximum data trasmission claimed is upto 210Mbps. Currently this has been used largely to build smart homes. Just like most new network technologies, PLC initially did not have any standard and various PLC devices faced serious issues when communicating with each other. In Dec 2008, IEEE has released IEEE P190l draft for Power line communications which defines medium access control and specifications of physical layer.
According to IEEE, this is to create a new standard for high speed 100 Mbps at the physical layer) communication devices via AC power lines, called Broadband over Power Line (BPL) devices. IEEE cla.ims this standard will use transmission frequencies below 100 Mhz and will be usable by all classes of BPL devices, including BPL devices used for the firstmile/last-mile connection (<1500 m to the premises) to broadband services as well as BPL devices used in buildings for LAN and other data distribution networks(<100m between devices).