| Ethernet technology has been developed quickly for its low cost and high flexibility. Recently, EPON has been widely used by Provider in access network and PBT will play an important role in carrier grade backbone ethernet to meet the demands of the next generation network. Once both can be combined with their technological advantages, more application scopes will be expanded.In order to achieve high security for part of users in network, this paper designs a scheme of encapsulation mechanism in ONU with EPON and PBT technologies. Based on the interconnection network, this scheme moves the encapsulation mechanism from the edge node of PBT to ONU, which realizes end-to-end Ethernet service of optical transmission. Some problems should be discussed because of the forward encapsulation mechanism. And other Ethernet data will still be encapsulated in the edge node of PBT so that it can achieve service differentiation and save the cost.For meeting the time synchronization requirements of various services in network, this paper introduces precise time synchronization of IEEE1588v2from metropolitan area network to access network that builds the unified time synchronous net. In access network, it applies the mixed model of time synchronous mechanism to satisfy various terminal environments of access network for different users. It not only expands PTP transmission message, but also improves PTP mechanism by ranging technology of EPON. It optimizes transmission performance and improves efficiency of network.In addition, this paper designs the model of the forward encapsulation mechanism though a network simulational tool called OPNET. It proves the feasibility of scheme which is encapsulated in ONU. And we also detect the delay performance of common packets and encapsulated packets in BEB node. Based on this encapsulation scheme, it simulates and analyzes the time synchronous mechanism which verifies the accuracy of PTP and improved PTP in EPON. |
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