CCNA 1 Chapter 7 TCP/IP Protocol Suite and IP Addressing

www.ciscopress.comCopyright 2003

CCNA 1 Chapter 7

TCP/IP Protocol Suite and IP Addressing

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Objectives

• Introduction to TCP/IP

• Internet addresses

• Obtaining an IP address


History and Future of TCP/IP

• The U.S. Department of Defense (DoD) created the TCP/IP reference model because it wanted a network that could survive any conditions.

• Some of the layers in the TCP/IP model have the same name as layers in the OSI model.


Application Layer

• Handles high-level protocols, issues of representation, encoding, and dialog control.

• The TCP/IP protocol suite combines all application related issues into one layer and ensures this data is properly packaged before passing it on to the next layer.


Application Layer Examples

• Telnet – Provides the capability to remotely access another computer

• File Transfer Protocol – Download or upload files• Hypertext Transfer Protocol – Works with the

World Wide Web


Transport Layer

Five basic services:• Segmenting upper-layer application data• Establishing end-to-end operations• Sending segments from one end host to another

end host• Ensuring data reliability• Providing flow control


Layer 4 Protocols


Internet Layer

• The purpose of the Internet layer is to send packets from a network node and have them arrive at the destination node independent of the path taken.

• Internet layer protocols:– Internet Protocol (IP)– Internet Control Message Protocol (ICMP) – Address Resolution Protocol (ARP)– Reverse Address Resolution Protocol (RARP)


Network Access Layer

• The network access layer is concerned with all of the issues that an IP packet requires to actually make a physical link to the network media.

• It includes the LAN and WAN technology details, and all the details contained in the OSI physical and data link layers.


Comparing the OSI Model and TCP/IP Model


Similarities of the OSI and TCP/IP models

• Both have layers.• Both have application layers, though they

include very different services.• Both have comparable transport and network

layers. • Packet-switched, not circuit-switched,

technology is assumed.

• Networking professionals need to know both models.


Differences of the OSI and TCP/IP models

• TCP/IP combines the presentation and session layer into its application layer.

• TCP/IP combines the OSI data link and physical layers into one layer.

• TCP/IP appears simpler because it has fewer layers.

• TCP/IP transport layer using UDP does not always guarantee reliable delivery of packets as the transport layer in the OSI model does.


Internet Architecture

• Two computers, anywhere in the world, following certain hardware, software, protocol specifications, can communicate, reliably even when not directly connected.

• LANs are no longer scalable beyond a certain number of stations or geographic separation.


Internet Addresses


IP Address as a 32-Bit Binary Number


Binary and Decimal Conversion


IP Address Classes


IP Address Classes


IP Addresses as Decimal Numbers


Hosts for Classes of IP Addresses

Class A (24 bits for hosts) 224 - 2* = 16,777,214 maximum hosts

Class B (16 bits for hosts) 216 - 2* = 65,534 maximum hosts

Class C (8 bits for hosts) 28 - 2* = 254 maximum hosts

* Subtracting the network and broadcast reserved address


IP Addresses as Decimal Numbers


An IP address such as 176.10.255.255 that has all binary 1s in the host bit positions is reserved for the broadcast address.

An IP address such as 176.10.0.0 that has all binary 0s in the host bit positions is reserved for the network address.

Network IDs and Broadcast Addresses


Private Addresses


Reserved Address Space

• Network ID• Broadcast address• Hosts for classes of IP addresses


Basics of Subnetting

• Classical IP addressing• Subnetworks• Subnet mask• Boolean operations: AND, OR, and NOT• Performing the AND function


Subnetworks

To create a subnet address, a network administrator borrows bits from the original host portion and designates them as the subnet field.


Subnetworks


Subnet Mask

• Determines which part of an IP address is the network field and which part is the host field

• Follow these steps to determine the subnet mask:– 1. Express the subnetwork IP address in binary form.– 2. Replace the network and subnet portion of the

address with all 1s.– 3. Replace the host portion of the address with all 0s.– 4. Convert the binary expression back to dotted-decimal

notation.


Subnet mask in decimal = 255.255.240.0

Subnet Mask


• AND is like multiplication. • OR is like addition. • NOT changes 1 to 0, and 0 to 1.

Boolean Operations: AND, OR, and NOT


Performing the AND Function


Range of Bits Needed to Create Subnets


Subnet Addresses


Decimal Equivalents of 8-Bit Patterns


Creating a Subnet

• Determining subnet mask size• Computing subnet mask and IP address• Computing hosts per subnetwork• Boolean AND operation• IP configuration on a network diagram• Host and subnet schemes• Private addresses


Class B address with 8 bits borrowed for the subnet

130.5.2.144 (8 bits borrowed for subnetting) routes to subnet 130.5.2.0 rather than just to network 130.5.0.0.

Determining Subnet Mask Size


The address 197.15.22.131 would be on the subnet 197.15.22.128.

11000101 00001111 00010110 100 00011

Network Field SNHost Field

Class C address 197.15.22.131 with a subnet mask of 255.255.255.224 (3 bits borrowed)

Determining Subnet Mask Size


Subnetting Example with AND Operation


The router connects subnetworks and networks.

IP Configuration on a Network Diagram


The number of lost IP addresses with a Class C network depends on the number of bits borrowed for subnetting.

Host Subnet Schemes


IPv4 versus IPv6

• IP version 6 (IPv6) has been defined and developed.

• IPv6 uses 128 bits rather than the 32 bits currently used in IPv4.

• IPv6 uses hexadecimal numbers to represent the 128 bits.

IPv4


Obtaining an IP Address


Obtaining an IP Address

• Static addressing– Each individual device must be configured with an IP

address.• Dynamic addressing

– Reverse Address Resolution Protocol (RARP)– Bootstrap Protocol (BOOTP)– Dynamic Host Configuration Protocol (DHCP)– DHCP initialization sequence– Function of the Address Resolution Protocol– ARP operation within a subnet


Static Assignment of IP Addresses

• Each individual device must be configured with an IP address.


Reverse Address Resolution Protocol (RARP)

The source initiates a RARP request, which helps it detect its own IP address.


BOOTP IP

• The Bootstrap Protocol (BOOTP) operates in a client/server environment and only requires a single packet exchange to obtain IP information.

• BOOTP packets can include the IP address, as well as the address of a router, the address of a server, and vendor-specific information.


Dynamic Host Configuration Protocol

• Allows a host to obtain an IP address using a defined range of IP addresses on a DHCP server.

• As hosts come online, contact the DHCP server, and request an address.


Client collects DHCP offer responses from the server.

DHCP Initialization Sequence


ARP

t

ARP enables a computer to find the MAC addressof the computer that isassociated with an IPaddress.


All devices on the network receive the packet and pass tonetwork layer; only one device responds with an ARP reply.

ARP Operation Within a Subnet


ARP Process


Advanced ARP Concepts

• Default gateway

• Proxy ARP


A default gateway is the IPaddress of the interface on the router that connects to the network segment on which the source host is located.

Default Gateway


How ARP Sends Data to Remote Networks


Proxy ARP

Documents

CCNA 1 Chapter 7 TCP/IP Protocol Suite and IP Addressing