Synchronization for SDH can be transported over Ethernet and vice versa. This enables Synchronous Ethernet network equipment to be connected to the same synchronization network as Synchronous Digital Hierarchy (SDH). Synchronization network model for Synchronous Ethernet, SONET and SDHĮxtension of the synchronization network to consider Ethernet as a building block (ITU-T G.8261). 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. G.8264 that describes the specification of Ethernet Synchronization Messaging Channel (ESMC) G.8262 that specifies Synchronous Ethernet clocks for SyncE G.8261 that defines aspects about the architecture and the wander performance of SyncE networks SyncE was standardized by the ITU-T, in cooperation with IEEE, as three recommendations: IETF’s Network Time Protocol, IEEE's 1588-2008 Precision Time Protocol are some of them. Several means are defined to address this issue. Unlike time-division multiplexing networks, the Ethernet family of computer networks do not carry clock synchronization information. Applications include cellular networks, access technologies such as Ethernet passive optical network, and applications such as IPTV or VoIP, as well as CERN's White Rabbit Project for sub-nanosecond time synchronization of data acquisition equipment for their high-energy experiments. 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. The aim of Synchronous Ethernet is to provide a synchronization signal to those network resources that may eventually require such a type of signal. Mobile Networks require a kind of synchronization
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