Bài giảng Network - Chapter 06

Chapter Overview IPIPXNetBEUIAppleTalk 1Network Layer Protocols Responsible for end-to-end communications on an internetworkContrast with data-link layer protocols, which provide communications on the same local area network (LAN) 2IP Encapsulation3IP Functions EncapsulationAddressingRoutingFragmentationProtocol identification 4The IP Datagram Format 5IP 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. 6End Systems and Intermediate Systems 7Fragmentation 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. 8Fragmentation (Cont.)9Protocol Field Values 0IP1ICMP 3Gateway-to-Gateway Protocol (GGP) 6TCP 8Exterior Gateway Protocol (EGP) 17UDP 10The IPX Standard Developed by Novell for use with NetWare Proprietary; never published as a public standardReverse engineered by Microsoft to create NWLink 11IPX Functions RoutingAddressingProtocol identification 12The IPX Header Format13IPX Addressing Internet Packet Exchange (IPX) uses Separate node and network addressesNetwork interface adapter hardware addresses for node addresses Network addresses Are assigned by administrators Do not need to be registered 14NetBEUI Characteristics Original Microsoft Windows default networking protocolDesigned for small local area networks (LANs)Does not support Internet communicationsDoes not need configuration Can be used to troubleshoot Transmission Control Protocol/Internet Protocol (TCP/IP) configuration protocols 15NetBIOS Names Assigned to computers during Windows installationSixteen characters long; the sixteenth character is a resource identifierCan identify computers, domain controllers, users, groups, and other resourcesHave no network identifier (which is why NetBEUI is nonroutable) 16The NBF Protocol Format17Protocols Using NBF Name Management Protocol (NMP)Session Management Protocol (SMP)User Datagram Protocol (UDP)Diagnostic and Monitoring Protocol (DMP) 18AppleTalk Data-Link Layer Options LocalTalkEtherTalkFast EtherTalkTokenTalkFDDITalk 19Datagram Delivery Protocol AppleTalk’s network layer protocolProvides packet addressing, routing, and protocol identificationHas short-format and long-format packet headers 20AppleTalk 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.21AppleTalk 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. 22Chapter 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. 23