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Synchronous Ethernet, also referred as SyncE, is an ITU-T standard for computer networking that facilitates the transference of clock signals over the Ethernet physical layer. This signal can then be made traceable to an external clock. ==Overview== The aim of Synchronous Ethernet is to provide a synchronization signal to those network resources that may eventually require such a type of signal. The Synchronous Ethernet signal transmitted over the Ethernet physical layer should be traceable to an external clock, ideally a master and unique clock for the whole network. Applications include cellular networks, access technologies such as Ethernet passive optical network, and applications such as IPTV or VoIP. Unlike time-division multiplexing networks, the Ethernet family of computer networks do not carry clock synchronization information. Several means are defined to address this issue. IETF’s Network Time Protocol, IEEE's 1588-2008 Precision Time Protocol are some of them. SyncE was standardized by the ITU-T, in cooperation with IEEE, as three recommendations: # ITU-T Rec. G.8261 that defines aspects about the architecture and the wander performance of SyncE networks # ITU-T Rec. G.8262 that specifies Synchronous Ethernet clocks for SyncE # ITU-T Rec. G.8264 that describes the specification of Ethernet Synchronization Messaging Channel (ESMC) SyncE architecture minimally requires replacement of the internal clock of the Ethernet card by a phase locked loop in order to feed the Ethernet PHY. 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「Synchronous Ethernet」の詳細全文を読む スポンサード リンク
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