The Research And Design Of PTP Protocol Based On The Distributed Equipment

The network time synchronization of routers and switches is the key technology of the communication system.Along with the era of all IP in the LTE coming,time synchronization accuracy improves continually.At present, there are mainly three types of synchronization methods: GPS synchronization,PTP protocol, listening to the network realizing synchronization between the base stations.This article mainly researched the application of PTP protocol including the IEEE 1588 Version 2 and IEEE 802.1 AS based on the distributed routers and switches. PTP protocol has met the requirement of the microsecond in the distributed equipment.Distributed equipment mainly consist of main control board, standby control board, interface board, network board.The clock buckle is located in the main control board.The ports of interface board as PTP ports interacted PTP packet with other equipment.Distribution equipment located in different locations in the MAN(metropolitan area network) widely used in wired communication of PTN network,including four different clock mode in application.When network topology changes and link failures and so on,ethernet ports participating in time synchronization will be adopted BMC algorithm to elect port role according to the specific protocol.Through slave port interacting with PTP packet obtains timestamp and calculates link delay time,the main control board adjusted the time on the clock buckle,and through BroadSync time synchronization method adjusting the time on the interface board.Paper researched the frame structure and message processing flow in the distributed equipment and the clock synchronous process in all single boards.This paper tested PTP protocol conformance adopting the TTCN- 3 protocol on distributed equipment.Through the analysis of the test requirements,we have developed test plan, defined the test module and message template, program design, etc.In this paper, test content contains each field in the various protocol messages. And using anomaly message by changing the attribute value of the messages attacked the equipment to test whether the equipment can make the right judgment.By executing the global program and analyzing test results,we can make the equipment meeting the requirements of protocol conformance.Finally, this paper introduced the method by VTP client logining distributed device to configure and manage equipment in the CLI and running the TCL script to improve test efficiency,and introduced typical examples of clock synchronization scheme.In order to make the test work comprehensive and efficient,we set up reasonable test scenarios for the various clock modes and clock synchronization mechanism.