network protocols handbook.pdf

300Protocols GuideAppleTalk: Apple Computer Protocols SuiteDescriptionAppleTalk is a multi-layered protocol of Apple Computers providing internetworkrouting, transaction and data stream service, naming service andcomprehensive file and print sharing among Apple systems using the Local-Talk interface built into the Apple hardware. AppleTalk ports to other networkmedia such as Ethernet by the use of LocalTalk to Ethernet bridges or byEthernet add-in boards for Apple machines. Many third-party applicationsexist for the AppleTalk protocols.An AppleTalk network can support up to 32 devices and data can be exchangedat a speed of 230.4 kilobits per second (Kbps). Devices can be asmuch as 1,000 feet apart. At the physical level, AppleTalk is a network with abus topology that uses a trunk cable between connection modules.The LocalTalk Link Access Protocol (LLAP) must be common to all systemson the network bus and handles the node-to-node delivery of data betweendevices connected to a single AppleTalk network. Data link layer interfacesto Ethernet, Token ring and FDDI are defined.The Datagram Delivery Protocol (DDP) is the AppleTalk protocol implementedat the network layer. DDP is a connectionless datagram protocol providingbest-effort delivery, which is similar to IP in the TCP/IP suite.At the Transport Layer, several protocols exist to add different types of functionalityto the underlying services. The Routing Table Maintenance Protocol(RTMP) allows bridges and internet routers to dynamically discover routesto the different AppleTalk networks in an internet. The AppleTalk TransactionProtocol (ATP) is responsible for controlling the transactions betweenrequestor and responder sockets.The Name Binding Protocol (NBP) is for the translation of a character stringname into the internet address of the corresponding client. The AppleTalkEcho Protocol (AEP) allows a node to send data to any other node on anAppleTalk internet and receive an echoed copy of that data in return. TheAppleTalk Data Stream Protocol (ADSP) is designed to provide byte-streamdata transmission in a full duplex mode between any two sockets on anAppleTalk internet. The Zone Information Protocol (ZIP) is used to maintainan internet-wide mapping of networks to zone names.In the Session Layer, the AppleTalk Session Protocol (ASP) is designed tointeract with AppleTalk Transaction Protocol (ATP) to provide for establishing,maintaining and closing sessions.The AppleTalk Filing Protocol (AFP) is an application or presentation layerprotocol designed to control access to remote file systems. A key applicationusing this protocol is the AppleShare for file sharing among a variety of usercomputers.