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Chapter Overview. IP IPX NetBEUI AppleTalk. Network Layer Protocols. Responsible for end-to-end communications on an internetwork Contrast with data-link layer protocols, which provide communications on the same local area network (LAN). IP Encapsulation. IP Functions. Encapsulation
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Chapter Overview • IP • IPX • NetBEUI • AppleTalk
Network Layer Protocols • Responsible for end-to-end communications on an internetwork • Contrast with data-link layer protocols, which provide communications on the same local area network (LAN)
IP Functions • Encapsulation • Addressing • Routing • Fragmentation • Protocol identification
IP Addresses • Internet Protocol (IP) is the only network layer protocol with its own addressing system. • IP addresses are 32 bits long. • IP addresses have two parts: a network identifier and a host identifier. • IP addresses are assigned to network interface adapters, not to computers. • The Source IP Address field in the IP header always identifies the computer that generated the packet. • The Destination IP Address field in the IP header always identifies the packet’s final destination.
Fragmentation • Routers connect networks that support different-sized packets. • The largest packet size supported by a network is called its maximum transmission unit (MTU). • When a packet is too large to be forwarded to a particular network, the router splits it into fragments. • Each fragment is encapsulated with a header and is transmitted as a separate packet. • Fragments are not reassembled until they reach their final destination. • Fragments can themselves be fragmented.
The IPX Standard • Developed by Novell for use with NetWare • Proprietary; never published as a public standard • Reverse engineered by Microsoft to create NWLink
IPX Functions • Routing • Addressing • Protocol identification
IPX Addressing • Internet Packet Exchange (IPX) uses • Separate node and network addresses • Network interface adapter hardware addresses for node addresses • Network addresses • Are assigned by administrators • Do not need to be registered
NetBEUI Characteristics • Original Microsoft Windows default networking protocol • Designed for small local area networks (LANs) • Does not support Internet communications • Does not need configuration • Can be used to troubleshoot Transmission Control Protocol/Internet Protocol (TCP/IP) configuration protocols
NetBIOS Names • Assigned to computers during Windows installation • Sixteen characters long; the sixteenth character is a resource identifier • Can identify computers, domain controllers, users, groups, and other resources • Have no network identifier (which is why NetBEUI is nonroutable)
Protocols Using NBF • Name Management Protocol (NMP) • Session Management Protocol (SMP) • User Datagram Protocol (UDP) • Diagnostic and Monitoring Protocol (DMP)
AppleTalk Data-Link Layer Options • LocalTalk • EtherTalk • Fast EtherTalk • TokenTalk • FDDITalk
Datagram Delivery Protocol • AppleTalk’s network layer protocol • Provides packet addressing, routing, and protocol identification • Has short-format and long-format packet headers
AppleTalk Addressing • AppleTalk computers have a unique 8-bit node ID that is self-assigned. • AppleTalk networks can have no more than 254 nodes. • AppleTalk uses 16-bit network numbers for routing. • Computers obtain network numbers using the Zone Information Protocol (ZIP). • Computer processes are identified by 8-bit socket numbers.
AppleTalk Addressing (Cont.) • Network numbers, node IDs, and socket numbers are expressed as three decimal numbers, separated by periods. • AppleTalk computers resolve node IDs into hardware addresses, using the AppleTalk Address Resolution Protocol (AARP). • AppleTalk computers also have friendly names and groups of computers called zones.
Chapter Summary • Network layer protocols are responsible for end-to-end communications across the network. • IP is a connectionless protocol that encapsulates transport layer data into datagrams. • IPX is a proprietary standard that performs routing, addressing, and protocol identification. • NetBIOS Extended User Interface (NetBEUI) is used by small Windows networks for LAN networking. • AppleTalk provides basic networking to small networks.