Design And Implementation Of BGP Based On Linux System

Internet is a kind of network consists of multiple interconnected autonomous systems. Border Gateway Protocol (BGP) is used to exchange Network Layer Reachability Information (NLRI) between multiple autonomous systems in Transmission Control Protocol/Internet Protocol (TCP/IP) networks. Analysis of BGP is significant to the development of Internet.This paper designs a BGP routing software based on Linux. This software includes two subsystems. One is BGP system used to run BGP protocol; another one is RMer system used to read or update Linux kernel route. RMer system is also used to send Linux kernel information to BGP system by RMER message.BGP system realizes the establishment between BGP neighbors, BGP route advertisement, BGP route aggregation, BGP route redistribution, management of BGP route attributes and BGP Finite State Machine (FSM) etc. BGP system communicates with RMer system by Linux local based TCP connection, RMer system communicates with Linux kernel by input/output control (ioctl). BGP system and RMer system commonly use VTY module to parse and process command line. System performs virtual thread mechanism, which includes six types threads, READ type thread is related to read operation, WRITE type thread is related to write operation, TIMER type thread is used to process time out event, EVENT type thread is used to process BGP FSM, READY type thread means this thread is ready to be scheduled, UNUSED type thread means this thread is idle.Linux system's powerful network functions and modular design technologies are widely used during the process of designing system, which is convenient to extend BGP functions and add new protocols. The test result of this system shows that the BGP protocol based on Linux TCP/IP protocols stack realize main BGP functions and can run stably. This research has certain academic and commercial value.