tailieunhanh - Network+ Certification (Outline) - Chapter 6: Network layer protocols

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, NetBEUI is used by small Windows networks for LAN networking, AppleTalk provides basic networking to small networks. | Chapter 6 Network Layer Protocols 1 Chapter Overview A. IP B. IPX C. NetBEUI D. AppleTalk Chapter 6 Lesson 1 IP 2 1. Network Layer Protocols A. Responsible for end-to-end communications across the internetwork B. Contrast with data-link layer protocols which provide communications on the same LAN 2. IP Characteristics A. Connectionless protocol 3 B. IP encapsulates transport layer data into units called datagrams. 1. Datagrams are addressed to the destination computer. 2. Datagrams remain intact during the trip to the destination even when they are encapsulated in several different data-link layer protocols. C. IP is responsible for carrying the traffic generated by virtually all of the other tCp IP protocols. 3. The IP Standard A. IP is defined in a document called Request For Comments RFC 791. B. RFCs are standards documents published by the Internet Engineering Task Force IETF . 4 4. IP Functions A. Encapsulation. The packaging of the transport layer data into a datagram B. Addressing. The identification of systems in the network using IP addresses C. Routing. The identification of the most efficient path to the destination system through the internetwork D. Fragmentation. The division of data into fragments of an appropriate size for transmission over the network E. Protocol identification. The specification of the transport layer protocol that generated the data in the datagram 5. IP Encapsulation A. IP forms datagrams by adding a 20-byte header by default to the transport layer data. B. Some IP datagrams include options that add to the size of the header. 5 C. IP datagram format 1. Version 4 bits . Specifies the version of the IP protocol used to create the datagram a. The version in current use is 4 but IP version 6 is currently in development. 2. Internet Header Length IHL 4 bits . Specifies the length of the datagram s header in 32-bit 4-byte words a. The typical length of a datagram header is five words 20 bytes . 1 If the datagram includes additional .