© Wiley Inc All Rights Reserved. CCNA: Cisco Certified Network Associate Study Guide CHAPTER 2: Internet Protocols

© Wiley Inc All Rights Reserved. The CCNA exam topics covered in this chapter include the following: Technology Evaluate TCP/IP communication processes and its associated protocols

© Wiley Inc All Rights Reserved. TCP/IP and the DoD Model The DoD model is basically a condensed version of the OSI model—it’s composed of four, instead of seven, layers:   Process/Application layer   Host-to-Host layer   Internet layer   Network Access layer

© Wiley Inc All Rights Reserved. The TCP/IP Protocol Suite TCP/IP and the DoD Model

© Wiley Inc All Rights Reserved. Process/Application Layer Protocols Telnet File Transfer Protocol (FTP) Trivial File Transfer Protocol (TFTP) Network File System (NFS) Simple Mail Transfer Protocol (SMTP) Line Printer Daemon (LPD) X Window Simple Network Management Protocol (SNMP) Domain Name Service (DNS) Dynamic Host Configuration Protocol (DHCP)/BootP (Bootstrap Protocol) TCP/IP and the DoD Model

© Wiley Inc All Rights Reserved. Host-to-Host Layer Protocols TCP/IP and the DoD Model Transmission Control Protocol (TCP) Header

© Wiley Inc All Rights Reserved. Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Application Transport Connection- Oriented Connectionless NNTP(119), HTTP (80), HTTPS (443), Telnet (23), FTP (21), SMTP (25): TCP TFTP (69), SNMP(161): UDP DNS (53): both TCP and UDP Transport Layer Overview

© Wiley Inc All Rights Reserved. Transmission Control Protocol (TCP) Connection-oriented services Uses virtual circuits (three-way handshake) Enables devices to send large quantities of data using windowing in a connection-oriented manner Uses acknowledgements Considered reliable Dest Port Dest Port Source Port Source Port CRC Data Segment … … Ack. Number Ack. Number Window number Window number Sequence number Sequence number

© Wiley Inc All Rights Reserved. Host-to-Host Layer Protocols TCP/IP and the DoD Model User Datagram Protocol (UDP) Header

© Wiley Inc All Rights Reserved. User Datagram Protocol (UDP) Simple connectionless service No windowing No sequencing No acknowledgements, which reduces overhead traffic Note: TCP and UDP both have source and destination port numbers and a CRC field Dest Port Dest Port Source. Port Source. Port CRC Data Segment Length

© Wiley Inc All Rights Reserved. Key Concepts of Host-to-Host Protocols TCP/IP and the DoD Model

© Wiley Inc All Rights Reserved. Port Numbers < 1024: “Well-known port numbers” –Defined in RFC 3232; linked to specific applications or protocols 1024: Dynamically assigned –Used by upper layers to communicate between hosts TCP/IP and the DoD Model

© Wiley Inc All Rights Reserved. Internet Layer Protocols Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) Proxy ARP TCP/IP and the DoD Model

© Wiley Inc All Rights Reserved. Internet Layer Protocols TCP/IP and the DoD Model

© Wiley Inc All Rights Reserved. Internet Protocol (IP) Provides network addressing and routing through an internetwork Connectionless service Dest Port Dest Port Source Port Source Port … … Data Segment Dest IP Dest IP Source IP Source IP Protocol Segment Packet … …

© Wiley Inc All Rights Reserved. Internet Layer Protocols TCP/IP and the DoD Model

© Wiley Inc All Rights Reserved. Local APR Broadcast TCP/IP and the DoD Model

© Wiley Inc All Rights Reserved. RARP Broadcast TCP/IP and the DoD Model

© Wiley Inc All Rights Reserved. Proxy ARP Allows a router to respond to an ARP request that is intended for a remote host How do we send packets out of the local network with multiple default gateways? But proxy Arp can cause network congestion…

© Wiley Inc All Rights Reserved. IP Addressing Hierarchical Addressing Framework Network.node addressing, 32 bits (4- bytes) The Hierarchical advantage is increased ability of addresses

© Wiley Inc All Rights Reserved. Binary to Decimal The following table shows the decimal values of each bit location in a nibble and a byte. Remember, a nibble is 4 bits and a byte is 8 bits. Nibble valuesByte values What all this means is that if a one digit (1) is placed in a value spot, then the nibble or byte takes on that decimal value, and adds it to any other value spots that have a one. And if a zero (0) is placed in a bit spot, then you don’t count that value.

© Wiley Inc All Rights Reserved. Binary to Decimal Review Converting binary to decimal examples: : Bit values = = = = = = 255 What is the hex equivalent of each binary number?

© Wiley Inc All Rights Reserved. Binary (Cont.) Bits Binary Decimal

© Wiley Inc All Rights Reserved. IP Addressing The Hierarchical IP Addressing Scheme Dotted-decimal, as in Binary, as in Hexadecimal, as in AC.10.1E.38

© Wiley Inc All Rights Reserved. Reserved IP Addresses IP Addressing AddressFunction Network address of all 0sInterpreted to mean “this network or segment.” Network address of all 1sInterpreted to mean “all networks.” Network Reserved for loopback tests. Designates the local node and allows that node to send a test packet to itself without generating network traffic. Node address of all 0sInterpreted to mean “network address” or any host on specified network. Node address of all 1sInterpreted to mean “all nodes” on the specified network; for example, means “all nodes” on network (Class B address). Entire IP address set to all 0sUsed by Cisco routers to designate the default route. Could also mean “any network.” Entire IP address set to all 1s (same as ) Broadcast to all nodes on the current network; sometimes called an “all 1s broadcast” or limited broadcast.

© Wiley Inc All Rights Reserved. Summary of the Three Classes of Networks IP Addressing

© Wiley Inc All Rights Reserved. Class A Addresses Structure –Network –Network.node.node.node Class A Valid Host IDs – All host bits off – All host bits on –Valid hosts = ’s & 255s can be valid hosts but all hosts bits cannot all be off or on at the same time! = 2 22 IP Addressing

© Wiley Inc All Rights Reserved. Class B Addresses Structure –NetworkNetwork –Network.Network.node.node Class B Valid Host IDs – All host bits off – All host bits on –Valid hosts = ’s & 255s can be valid hosts but all hosts bits cannot all be off or on at the same time! = 2 14 IP Addressing

© Wiley Inc All Rights Reserved. Class C Addresses Structure –NetworkNetworkNetwork –Network.Network.Network.node Class C Valid Host IDs – All host bits off – All host bits on –Valid hosts = ’s & 255s can be valid hosts but all hosts bits cannot all be off or on at the same time! = 2 6 IP Addressing

© Wiley Inc All Rights Reserved. Private IP Addresses IP Addressing Address ClassReserved address space Class A through Class B through Class C through

© Wiley Inc All Rights Reserved. Broadcast Addresses

© Wiley Inc All Rights Reserved. Broadcast Addresses Layer 2 Broadcasts—These are sent to all nodes on a LanLayer 2 Broadcasts—These are sent to all nodes on a Lan Broadcasts (layer 3)—These are sent to all notes on the networkBroadcasts (layer 3)—These are sent to all notes on the network Unicast—These are sent to a single destination hostUnicast—These are sent to a single destination host Multicast—These are packets sent from a single source, and transmitted to many devices on different networksMulticast—These are packets sent from a single source, and transmitted to many devices on different networks