TCP IP Illustrated

292 sun remote procedure call most network

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Unformatted text preview: the same order? file:///D|/Documents%20and%20Settings/bigini/Doc...omenet2run/tcpip/tcp-ip-illustrated/smtp_sim.htm (23 of 23) [12/09/2001 14.47.53] Chapter 29. NFS: Network File System NFS: Network File System 29.1 Introduction In this chapter we describe NFS, the Network File System, another popular application that provides transparent file access for client applications. The building block of NFS is Sun RPC: Remote Procedure Call, which we must describe first. Nothing special need be done by the client program to use NFS. The kernel detects that the file being accessed is on an NFS server and automatically generates the RPC calls to access the file. Our interest in NFS is not in all the details on file access, but in its use of the Internet protocols, especially UDP. 29.2 Sun Remote Procedure Call Most network programming is done by writing application programs that call systemprovided functions to perform specific network operations. For example, one function performs a TCP active open, another performs a TCP passive open, another sends data across a TCP connection, another sets specific protocol options (enable TCP's keepalive timer), and so on. In Section 1.15 we mentioned that two popular sets of functions for network programming (called APIs) are sockets and TLI. The API used by the client and the API used by the server can be different, as can the operating systems running on the client and server. It is the communication protocol and application protocol that determine if a given client and server can communicate with each other. A Unix client written in C using sockets and TCP can communicate with a mainframe server written in COBOL using some other API and TCP, if both hosts are connected across a network and both have a TCP/IP implementation. Typically the client sends commands to the server, and the server sends replies back to the client. All the applications we've looked at so far - Ping, Traceroute, routing daemons, and the clients and servers for the DNS, TFTP, BOOTP, SNMP, Telnet, FTP, and SMTP-are b...
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