ccna r&s pdf

ccna r&s pdf.The remainder of this chapter will focus on layer 3 of the TCP/IP protocol stack, the Internet layer, which corresponds to the network layer of the OSI reference model. Protocol (ICMP), Open Shortest Path First (OSPF), and others. The next few subsections describe the components of an IP packet and some of the protocols that run at the Internet layer.Internet Protocol (IP) X is one of the many protocols that run at the Internet layer. In the networking industry, it is common to hear TCP/IP referred to simply as IP, which is a misnomer because IP is only one of many protocols included in the TCP/IP protocol cluster.IP provides connectionless, unreliable transport to Layer 3 devices, and it handles individual packets independently. If reliability and flowvolume control, TCP at the transport layer can provide this function.TCP is discussed in Chapter 8.The IP protocol provides the following main functions. . Connectionless data transfer: transfers data on a best-effort basis and does not provide data recovery.. Hierarchical logical addressing:Allows interconnected networks to be extremely scalable.The transport layer uses data segments to transfer information between devices, while the Internet layer uses datagrams (which, as stated in Chapter 2, are synonymous with packets). Table 5.1 lists the components of an IP datagram; in the absence of any options, the IP header is 20 bytes long.Table 5.1 Components of an IP datagram 1P field name length (bits) DescriptionVersion 4 IP version number, e.g. IPv4Header length 4 Length of IP header in 32-bit wordsPriority and TOS (type of service) 8 Specifies how the IP network should handle the datagram