Chapter 2 Introduction to TCPIP

8/8/2019 Chapter 2 Introduction to TCPIP

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CCNA BootcampChapter 2: Introduction to TCP/IP


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Chapter 2 Objectives

The CCNA Topics Covered in this chapter include:

TCP/IP and the DoD Model

Process/Application Layer

Host-to-Host Layer

Internet Layer Network Access

IP Addressing

Class A Class B

Class C

Private Addressing


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TCP/IP and the DoD Model

The figure sho w s a compa rison of the DoD m odel and the OSI refer encem odel. As you can see, the two ar e similar in concept, but each has a

differen t num ber of layers with differen t nam es.


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The TCP/IP Protocol Suite

The DoD and OSI mo dels are alike in design and conceptand have similar functions in sim ilar layers.


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Process/Application Layer

This section describes different applications and servicestypically used in IP networks. The following protocols

and applications are discussed:

Telnet FTP

TFTP NFS SMTP LPD X Window SNMP DNS

DHCP/BootP


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Host to Host Layer

The main purpose of the Host-to-Host layer is to shield theupper-layer applications from the complexities of thenetwork.

This layer says to the upper layer, Just give me your datastream, with any instructions, and Ill begin the process of

getting your information ready to send.

The following sections describe the two protocols at this layer:

Transm ission Control Protocol (TCP)

User Datagram Protocol (UDP)


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TCP

The figure shows the different fields within theTCP header.


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UDP

This figure clearly illustrates UDPs markedly low

overhead as compared to TCPs hungry usage.


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Key concepts of Host to Host Protocols

TCP UDP

Sequenced Unsequenced

Reliable Unreliable

Connection-oriented Connectionless

Virtual circuit Low overhead Acknowledgments No acknowledgment

Windowing flow control No windowing or flow control


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Port Numbers

Port number examples for TCP and UDP


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Key Protocols and Port Numbers

TCP UDP

Telnet 23 SNMP 161SMTP 25 TFTP 69HTTP 80 DNS 53FTP 21DNS 53HTTPS 443


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Internet Layer

IP Header


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Internet Layer

Protocol Field in IP Header


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Internet Layer

Protocol Field in IP Header

Protocol Protocol NumberICMP 1

IP in IP (tunneling) 4IGRP 9EIGRP 88OSPF 89IPv6 41GRE 47Layer 2 tunnel (L2TP) 115


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Internet Layer

ICMP

Internet Control Message Protocol (ICMP) works at theNetwork layer and is used by IP for many different services.

ICMP is a management protocol and messaging serviceprovider for IP.Its messages are carried as IP datagrams.

ICMP packets have the following characteristics: They can provide hosts with information about network problems. They are encapsulated within IP datagrams.


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Internet Layer

ICMPE0 of LAB_B goes down. What happens?


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Internet Layer

ARP

ARP resolves IP addresses to Ethernet (MAC) addresses.


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Internet Layer

RARP


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IP Addressing

An IP address is a numeric identifier assigned to eachmachine on an IP network.

It designates the specific location of a device on the network.

IP addressing was designed to allow hosts on one network tocommunicate with a host on a different network regardless ofthe type of LANs the hosts are participating in.


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IP Terminology

BIT: A bit is one digit, either a 1 or a 0.

BYTE: A byte is 7 or 8 bits, depending on whether parity is used. For the

rest of this chapter, always assume a byte is 8 bits.

OCTET: An octet, made up of 8 bits, is just an ordinary 8-bit binarynumber. In this chapter, the terms byte and octet are completely

interchangeable.

Network address: This is the designation used in routing to sendpackets to a remote networkfor example, 10.0.0.0, 172.16.0.0, and

192.168.10.0.

Broadcast address: The address used by applications and hosts tosend information to all nodes on a network is called the broadcastaddress.


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Network Addressing

Subdividing an IP address into a network and node addressis determined by the class designation of ones network.

This figure summarizes the three classes of networks


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Networ k Addr ess Range: Class A

The designers of the IP address scheme said that the first bit of thefirst byte in a Class A network address must always be off, or 0. Thismeans a Class A address must be between 0 and 127 in the firstbyte, inclusive.

Consider the following network address: 0xxxxxxx

If we turn the other 7 bits all off and then turn them all on, well find

the Class A range of network addresses:00000000 = 0

01111111 = 127

In a Class A network address, the first byte is assigned to the

network address and the three remaining bytes are used for thenode addresses.

The Class A format is as follows: network.node.node.node

For example, in the IP address 49.22.102.70, the 49 is the networkaddress and 22.102.70 is the node address.


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Networ k Addr ess Range: Class B

In a Class B network, the RFCs state that the first bit ofthe first byte must always be turned on but the second bit

must always be turned off. If you turn the other 6 bits all off and then all on, you will

find the range for a Class B network:10000000 = 128

10111111 = 191 In a Class B network address, the first 2 bytes are

assigned to the network address and the remaining 2

bytes are used for node addresses. The format is as follows: network.network.node.node For example, in the IP address 172.16.30.56, the

network address is 172.16 and the node address is30.56.


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Networ k Addr ess Range: Class C

For Class C networks, the RFCs define the first 2 bits ofthe first octet as always turned on, but the third bit can

never be on. Following the same process as the previousclasses, convert from binary to decimal to find the range.

Heres the range for a Class C network:11000000 = 192

11011111 = 223 The first 3 bytes of a Class C network address are

dedicated to the network portion of the address, with only

1 measly byte remaining for the node address. Heres the format: network.network.network.node Using the example IP address 192.168.100.102, the

network address is 192.168.100 and the node address is102.


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Netw or k Address Ranges: Classes D and E

The addresses between 224 to 255 are reserved forClass D and E networks. Class D (224239) is usedfor multicast addresses and Class E (240255) forscientific purposes, but Im not going into these typesof addresses in this book (and you dont need toknow them).


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Reserved Addressing

Address FunctionNetwork 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.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 thespecified network

Entire IP address set to all 0s Used by Cisco routers to designate thedefault route. Could also mean anynetwork.

Entire IP address set to all 1s (same as Broadcast to all nodes on thecurrent network; 255.255.255.255)sometimes called an all 1s broadcast orlimited broadcast


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Private Addressing

Address Class Reserved Address Space

Class A 10.0.0.0 through 10.255.255.255Class B 172.16.0.0 through 172.31.255.255Class C 192.168.0.0 through 192.168.255.255


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Written Labs and Review Questions

Open your books and go through all the written labs andthe review questions.

Review the answers in class.


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Thank You

Chapter 2 Introduction to TCPIP

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Transcript of Chapter 2 Introduction to TCPIP