Bài giảng Network Certification Microsoft Press - Chapter 6

1Chapter Overview  IP  IPX  NetBEUI  AppleTalk 2Network 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) 3IP Encapsulation 4IP Functions  Encapsulation  Addressing  Routing  Fragmentation  Protocol identification 5The IP Datagram Format 6IP 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. 7End Systems and Intermediate Systems 8Fragmentation  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. 9Fragmentation (Cont.) 10 Protocol Field Values 0 IP 1 ICMP 3 Gateway-to-Gateway Protocol (GGP) 6 TCP 8 Exterior Gateway Protocol (EGP) 17 UDP 11 The IPX Standard  Developed by Novell for use with NetWare  Proprietary; never published as a public standard  Reverse engineered by Microsoft to create NWLink 12 IPX Functions  Routing  Addressing  Protocol identification 13 The IPX Header Format 14 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 15 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 16 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) 17 The NBF Protocol Format 18 Protocols Using NBF  Name Management Protocol (NMP)  Session Management Protocol (SMP)  User Datagram Protocol (UDP)  Diagnostic and Monitoring Protocol (DMP) 19 AppleTalk Data-Link Layer Options  LocalTalk  EtherTalk  Fast EtherTalk  TokenTalk  FDDITalk 20 Datagram Delivery Protocol  AppleTalk’s network layer protocol  Provides packet addressing, routing, and protocol identification  Has short-format and long-format packet headers 21 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. 22 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. 23 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.