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PME Aggregation Function (PAF) is a computer networking mechanism defined in Clause 61 of the IEEE 802.3 standard, which allows one or more Physical Medium Entities (PMEs) to be combined together to form a single logical Ethernet link. The PAF is located in the Physical Coding Sublayer (PCS), between the Media Access Control (MAC)-PHY Rate Matching function and the Transmission Convergence (TC) sublayer. It interfaces with the PMEs across the λ-interface, and to the MAC-PHY Rate Matching function using an abstract interface. PAF is an optional function which was defined before 2007 for two IEEE 802.3 interfaces: 2BASE-TL and 10PASS-TS, both of which were Ethernet in the First Mile (EFM) copper physical layers. ==Details== PME Aggregation function has the following characteristics: * Supports aggregation of up to 32 PMEs * Supports individual PMEs having different data rates (max 1:4 ratio) * Ensures low packet latency and preserves frame order * Scalable and resilient to PME failure * Independent of type of EFM copper PHY * Allows vendor discretionary algorithms for fragmentation PAF ''Transmit'' function works by fragmenting incoming Ethernet frames into a number of fragments, limited in size to a range between 64 and 512 Bytes. A sequential fragmentation header is prepended to each fragment, indicating if the fragment is from the start-of-packet, end-of-packet or middle of packet. A frame check sequence (FCS) is appended to each fragment, which is then transmitted by the next available active PME in the aggregated group. The following diagram illustrates the PAF fragmentation: PAF ''Receive'' function reassembles the original frames from the received fragments, which are buffered in a per-MAC fragment buffer. The algorithm uses the fragmentation header to make sure that the reassembled frames are in order. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「PME Aggregation Function」の詳細全文を読む スポンサード リンク
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