CCNA Cisco Certified Network Associate Study Guide CHAPTER

CCNA: Cisco Certified Network Associate Study Guide CHAPTER 2: Internet Protocols © Wiley Inc. 2006. 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. 2006. All Rights Reserved.

TCP/IP and the Do. D Model The Do. D 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. 2006. All Rights Reserved.

TCP/IP and the Do. D Model The TCP/IP Protocol Suite © Wiley Inc. 2006. All Rights Reserved.

TCP/IP and the Do. D Model 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)/Boot. P © Wiley Inc. 2006. All Rights Reserved. (Bootstrap Protocol)

TCP/IP and the Do. D Model Host-to-Host Layer Protocols Transmission Control Protocol (TCP) Header © Wiley Inc. 2006. All Rights Reserved.

Transport Layer Overview Application Transport Transmission Control Protocol (TCP) Connection. Oriented User Datagram Protocol (UDP) 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 © Wiley Inc. 2006. 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 Source Ack. Window Sequence Port Number number Segment … CRC Data © Wiley Inc. 2006. All Rights Reserved.

TCP/IP and the Do. D Model Host-to-Host Layer Protocols User Datagram Protocol (UDP) Header © Wiley Inc. 2006. All Rights Reserved.

User Datagram Protocol (UDP) • • Simple connectionless service No windowing No sequencing No acknowledgements, which reduces overhead traffic Segment Dest Port Source. Port Length CRC Data Note: TCP and UDP both have source and destination port numbers and a CRC field © Wiley Inc. 2006. All Rights Reserved.

TCP/IP and the Do. D Model Key Concepts of Host-to-Host Protocols © Wiley Inc. 2006. All Rights Reserved.

TCP/IP and the Do. D Model 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 © Wiley Inc. 2006. All Rights Reserved.

TCP/IP and the Do. D Model Internet Layer Protocols • • • Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) Proxy ARP © Wiley Inc. 2006. All Rights Reserved.

TCP/IP and the Do. D Model Internet Layer Protocols © Wiley Inc. 2006. All Rights Reserved.

Internet Protocol (IP) • Provides network addressing and routing through an internetwork • Connectionless service Segment Packet Dest IP Dest Port Source Protocol IP … … Data Segment © Wiley Inc. 2006. All Rights Reserved.

TCP/IP and the Do. D Model Internet Layer Protocols © Wiley Inc. 2006. All Rights Reserved.

TCP/IP and the Do. D Model Local APR Broadcast © Wiley Inc. 2006. All Rights Reserved.

TCP/IP and the Do. D Model RARP Broadcast © Wiley Inc. 2006. 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. 2006. 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. 2006. 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 values Byte values 8421 128 64 32 16 8 4 2 1 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. 2006. All Rights Reserved.

Binary to Decimal Review Converting binary to decimal examples: 128 64 32 16 8 4 2 1: Bit values 0 0 0 1 0 0 0 1 0 1 1 0 0 0 1 1 0 1 0 1 1 1 0 =0 1 = 15 1 = 85 1 = 131 0 = 22 1 = 255 What is the hex equivalent of each binary number? © Wiley Inc. 2006. All Rights Reserved.

Binary (Cont. ) Bits 0 1 2 3 4 5 6 7 8 Binary 0000 10000000 11100000 11111000 11111110 1111 Decimal 0 128 192 224 240 248 252 254 255 © Wiley Inc. 2006. All Rights Reserved.

IP Addressing The Hierarchical IP Addressing Scheme • Dotted-decimal, as in 172. 163. 30. 56 • Binary, as in 10101100. 00010000. 00011110. 00111000 • Hexadecimal, as in AC. 10. 1 E. 38 © Wiley Inc. 2006. All Rights Reserved.

IP Addressing Reserved IP Addresses Address Function Network address of all 0 s Interpreted to mean “this network or segment. ” Network address of all 1 s Interpreted to mean “all networks. ” Network 127. 0. 0. 1 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 0 s Interpreted to mean “network address” or any host on specified network. Node address of all 1 s Interpreted to mean “all nodes” on the specified network; for example, 128. 2. 255 means “all nodes” on network 128. 2 (Class B address). Entire IP address set to all 0 s Used by Cisco routers to designate the default route. Could also mean “any network. ” Entire IP address set to all 1 s (same as 255) Broadcast to all nodes on the current network; sometimes called an “all 1 s broadcast” or limited broadcast. © Wiley Inc. 2006. All Rights Reserved.

IP Addressing Summary of the Three Classes of Networks © Wiley Inc. 2006. All Rights Reserved.

IP Addressing Class A Addresses • Structure – Network. node Network • Class A Valid Host IDs – 10. 0 All host bits off – 10. 255 All host bits on – Valid hosts = 10. 0. 0. 1 - 10. 255. 254 • 0’s & 255 s can be valid hosts but all hosts bits cannot all be off or on at the same time! • 224 -2 = 222 © Wiley Inc. 2006. All Rights Reserved.

IP Addressing • Structure Class B Addresses – Network. node Network • Class B Valid Host IDs – 172. 16. 0. 0 All host bits off – 172. 16. 255 All host bits on – Valid hosts = 172. 16. 0. 1 - 172. 16. 255. 254 • 0’s & 255 s can be valid hosts but all hosts bits cannot all be off or on at the same time! • 216 -2 = 214 © Wiley Inc. 2006. All Rights Reserved.

IP Addressing Class C Addresses • Structure – Network. node Network • Class C Valid Host IDs – 192. 168. 100. 0 All host bits off – 192. 168. 100. 255 All host bits on – Valid hosts = 192. 168. 100. 1 - 192. 168. 100. 254 • 0’s & 255 s can be valid hosts but all hosts bits cannot all be off or on at the same time! • 28 -2 = 26 © Wiley Inc. 2006. All Rights Reserved.

IP Addressing Private IP Addresses Address Reserved address space Class A 10. 0 through 10. 255 Class B 172. 16. 0. 0 through 172. 31. 255 Class C 192. 168. 0. 0 through 192. 168. 255 © Wiley Inc. 2006. All Rights Reserved.

Broadcast Addresses © Wiley Inc. 2006. All Rights Reserved.

Broadcast Addresses • Layer 2 Broadcasts—These are sent to all nodes on a Lan • Broadcasts (layer 3)—These are sent to all notes on the network • Unicast—These are sent to a single destination host • Multicast—These are packets sent from a single source, and transmitted to many devices on different networks © Wiley Inc. 2006. All Rights Reserved.