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

© Wiley Inc. 2006. All Rights Reserved.

CCNA: Cisco Certified Network Associate Study

Guide

CHAPTER 2: Internet Protocols


The CCNA exam topics covered in this chapter include the following:

Technology•Evaluate TCP/IP communication processes and its associated protocols


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 layerHost-to-Host layerInternet layerNetwork Access layer


The TCP/IP Protocol Suite



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)



Host-to-Host Layer Protocols


Transmission Control Protocol (TCP) Header


Transmission ControlProtocol (TCP)

User Datagram Protocol (UDP)

Transmission ControlProtocol (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): UDPDNS (53): both TCP and UDP

Transport Layer Overview


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

DestPortDestPort

SourcePort

SourcePort CRCCRC DataData

Segment

……Ack.

NumberAck.

NumberWindownumberWindownumber

Sequencenumber

Sequencenumber


Host-to-Host Layer Protocols


User Datagram Protocol (UDP) Header


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

DestPortDestPort

Source.Port

Source.Port CRCCRC DataDataSegment LengthLength


Key Concepts of Host-to-Host Protocols



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



Internet Layer Protocols• Internet Protocol (IP)• Internet Control Message Protocol

(ICMP)• Address Resolution Protocol (ARP)• Reverse Address Resolution

Protocol (RARP)• Proxy ARP



Internet Layer Protocols



Internet Protocol (IP)

• Provides network addressing and routing through an internetwork

• Connectionless service

DestPortDestPort

SourcePort

SourcePort …… DataDataSegment

DestIP

DestIP

SourceIP

SourceIP ProtocolProtocol SegmentSegmentPacket ……


Internet Layer Protocols



Local APR Broadcast



RARP Broadcast



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…


IP Addressing

• Hierarchical Addressing Framework

• Network.node addressing, 32 bits (4-bytes)

• The Hierarchical advantage is increased ability of addresses


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

8 4 2 1 128 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.


Binary to Decimal Review

Converting binary to decimal examples:

128 64 32 16 8 4 2 1: Bit values 0 0 0 0 0 0 0 0 = 0 0 0 0 0 1 1 1 1 = 15 0 1 0 1 0 1 0 1 = 85 1 0 0 0 0 0 1 1 = 131 0 0 0 1 0 1 1 0 = 22 1 1 1 1 1 1 1 1 = 255

What is the hex equivalent of each binary number?


Binary (Cont.)Bits Binary

Decimal0 00000000 01 10000000 1282 11000000 1923 11100000 2244 11110000 2405 11111000 2486 11111100 2527 11111110 2548 11111111 255


IP AddressingThe Hierarchical IP Addressing

Scheme• Dotted-decimal, as in 172.163.30.56

• Binary, as in 10101100.00010000.00011110.00111000

• Hexadecimal, as in AC.10.1E.38


Reserved IP AddressesIP Addressing

Address Function

Network address of all 0s Interpreted to mean “this network or segment.”

Network address of all 1s 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 0s Interpreted to mean “network address” or any host on specified network.

Node address of all 1s Interpreted to mean “all nodes” on the specified network; for example, 128.2.255.255 means “all nodes” on network 128.2 (Class B address).

Entire IP address set to all 0s Used by Cisco routers to designate the default route. Could also mean “any network.”

Entire IP address set to all 1s (same as 255.255.255.255)

Broadcast to all nodes on the current network; sometimes called an “all 1s broadcast” or limited broadcast.


Summary of the Three Classes of Networks

IP Addressing


Class A Addresses• Structure

– NetworkNetwork.node.node.node

• Class A Valid Host IDs– 10.0.0.0 All host bits off– 10.255.255.255 All host bits on– Valid hosts = 10.0.0.1 - 10.255.255.254

• 0’s & 255s can be valid hosts but all hosts bits cannot all be off or on at the same time!

• 224-2 = 222

IP Addressing


Class B Addresses• Structure

– NetworkNetwork.NetworkNetwork.node.node

• Class B Valid Host IDs– 172.16.0.0 All host bits off– 172.16.255.255 All host bits on– Valid hosts = 172.16.0.1 - 172.16.255.254


• 216-2 = 214

IP Addressing


Class C Addresses• Structure

– NetworkNetwork.NetworkNetwork.NetworkNetwork.node

• 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


• 28-2 = 26

IP Addressing


Private IP Addresses

IP Addressing

Address Class

Reserved address space

Class A 10.0.0.0 through 10.255.255.255

Class B 172.16.0.0 through 172.31.255.255

Class C 192.168.0.0 through 192.168.255.255


Broadcast Addresses


Broadcast Addresses•Layer 2 Broadcasts—These are sent to all Layer 2 Broadcasts—These are sent to all nodes on a Lannodes on a Lan•Broadcasts (layer 3)—These are sent to all Broadcasts (layer 3)—These are sent to all notes on the networknotes on the network•Unicast—These are sent to a single Unicast—These are sent to a single destination hostdestination host•Multicast—These are packets sent from a Multicast—These are packets sent from a single source, and transmitted to many single source, and transmitted to many devices on different networksdevices on different networks

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

Documents

dod model slide

tcpip protocol suite

host layer protocols

host protocols tcpip

internet layer protocols

internet protocols

processapplication layer

hosts tcpip