Ccna1 M9 Tcp Ip And Ip Addressing

CCNA – Semester1

Module 9 TCP/IP and IP Addressing

Objectives

• Introduction to TCP/IP • Internet addresses • Obtaining an IP address

Introduction to TCP/IP

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. • In 1992 the standardization of a new generation of IP, IPv6, was supported by the Internet Engineering Task Force (IETF) with 128 bits long.

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.

Transport Layer • The transport layer provides transport services including flow control and reliability from the source host to the destination host. • The transport layer constitutes a logical connection between the endpoints of the network.

Internet Layer • The purpose of the Internet layer is to select the best path through the network for packets to travel. • The main protocol that functions at this layer is the Internet Protocol (IP).

IP - Internet Protocol • IP: provides connectionless, best-effort delivery routing of packets. IP is not concerned with the content of the packets but looks for a path to the destination. • IP performs the following operations: – Defines a packet and an addressing scheme – Transfers data between the Internet layer and network access layers – Routes packets to remote hosts

Other Internet Layer Protocols • Internet Control Message Protocol (ICMP) provides control and messaging capabilities. • Address Resolution Protocol (ARP) determines the data link layer address, MAC address, for known IP addresses. • Reverse Address Resolution Protocol (RARP) determines IP addresses when the MAC address is known.

Network Access Layer • The network access layer is also called the host-to-network layer. • Include the LAN and WAN technology details such as: Ethernet, Token-Ring, ISDN, Frame-Relay. • Include the mapping of IP addresses to physical hardware addresses and encapsulation of IP packets into frames.

Internet

• Two computers, anywhere in the world, following certain hardware, software, and protocol specifications, can communicate reliably.

Internet Addresses

Network and Host Addressing • IP address is hierarchical and has two parts: – First part identifies the network where the system is connected. – Second part identifies that particular system on the network.

IP Address Classes • IP addresses are divided into classes to define the large, medium, and small networks.

IP Address Classes

IP Address • The 127.0.0.0 network is reserved for loopback testing. • The Class D address class was created to enable multicasting in an IP address. A multicast address is a unique network address that directs packets with that destination address to predefined groups of IP addresses. • A Class E address is reserved these addresses for research.

Reserved IP Address • Certain host addresses are reserved and cannot be assigned to devices on a network. – Network address – Used to identify the network itself – Broadcast address – Used for broadcasting packets to all the devices on a network

Network address • Network address provide a convenient way to refer to all of the addresses on a particular network or subnetwork. • Two hosts with differing network address require a device, typically a router, in order to communicate. • An IP address that ends with binary 0s in all host bits is reserved for the network address.

Broadcast address • Broadcast goes to every host with a particular network ID number. • An IP address that ends with binary 1s in all host bits is reserved for the directed broadcast address. • An IP address with binary 1s in all network bits and host bits is reserved for the local broadcast address.

Local broadcast address

255.255.255.255

STOP

Directed broadcast address

192.168.20.0 192.168.20.255

Example: 172.16.20.200 • • • • •

172.16.20.200 is Class B address Network portion: 172.16 Host portion: 20.200 Network address: 172.16.0.0 Broadcast address: 172.16.255.255

Public IP Address • In order to connect to the Internet, every machines must have its own public IP address. Public IP addresses are unique. • With the rapid growth of the Internet, public IP addresses were beginning to run out. New addressing schemes are used so solve this: – Classless interdomain routing (CIDR) – IP version 6 (IPv6) – Network Address Translation (NAT)

Private Address

• •

Private networks can use private address to assign their machines in the local network. RFC 1918 sets aside three blocks of IP addresses for private, internal use. – Class A: 10.0.0.0 – Class B: 172.16.0.0 Æ 172.31.0.0 – Class C: 192.168.0.0 Æ 192.168.255.0

•

Connecting a network using private addresses to the Internet requires translation (overloading) of the private addresses to public addresses. This translation is served by NAT

Valid address? • • • • • • •

150.100.255.255 175.100.255.18 195.234.253.0 100.0.0.23 188.258.221.176 127.34.25.189 224.156.217.73

IPv4 versus IPv6 • • •

Introduced by IETF in 1992, IPv6, known as IPng, uses 128 bits rather than the 32 bits currently used in IPv4. IPv6 uses hexadecimal numbers to represent the 128 bits. IPv6 provides 640 sextrillion addresses. This version of IP should provide enough addresses for future communication needs.

Obtaining an IP address

Obtaining an IP Address

Static Assignment of IP Addresses • Each individual device must be configured with an IP address. • Keep very detailed records, because problems can occur on the network if you use duplicate IP addresses.

Dynamic addressing • There are a some different methods that you can use to assign IP addresses dynamically: – RARP: Reverse Address Resolution Protocol. – BOOTP: BOOTstrap Protocol. – DHCP: Dynamic Host Configuration Protocol.

IP

Reverse Address Resolution Protocol

BOOTP IP

• Network administrator creates a configuration file that specifies the parameters for each device. The administrator must add hosts and maintain the BOOTP database. • BOOTP packets can include the IP address, as well as the address of a router, the address of a server, and vendorspecific information.

Dynamic Host Configuration Protocol

• Successor to BOOTP. • Automatically allows a host to obtain an IP address from an IP pool • Use 4-steps IP registration and requires IP leased time

DHCP Initialization Sequence

•

Broadcast request and discover DHCP server

•

Offer IP address, DHCP server address and Default Gateway address…

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Request for the offered IP statistics

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Acknownledge the request, confirm registration

Encapsulation

Address Resolution Protocol • In order for devices to communicate, the sending devices need both the IP addresses and the MAC addresses of the destination devices. • ARP enables a computer to find the MAC address of the computer that is associated with an IP address.

Address resolution protocol

ARP table in host

M A R

ARP operation ARP Table:

?

MAC MAC A.B.C.1.2.3 ?

IP IP Data 10.0.2.110.0.2.9

10.0.2.1 A.B.C.1.2.3

10.0.2.5 A.B.C.4.5.6

10.0.2.9 A.B.C.7.8.9

A

B

C

ARP operation: ARP request IP IP MAC MAC What is your MAC Addr? A.B.C.1.2.3 ff.ff.ff.ff.ff.ff 10.0.2.1 10.0.2.9

10.0.2.1 A.B.C.1.2.3

10.0.2.5 A.B.C.4.5.6

10.0.2.9 A.B.C.7.8.9

A

B

C

ARP operation: Checking IP IP MAC MAC What is your MAC Addr? A.B.C.1.2.3 ff.ff.ff.ff.ff.ff 10.0.2.110.0.2.9

is t P a I h y T m 10.0.2.1 A.B.C.1.2.3

10.0.2.5 A.B.C.4.5.6

10.0.2.9 A.B.C.7.8.9

A

B

C

ARP operation: ARP reply IP IP MAC MAC A.B.C.7.8.9 A.B.C.1.2.3 10.0.2.9 10.0.2.1

This is my MAC Addr

10.0.2.1 A.B.C.1.2.3

10.0.2.5 A.B.C.4.5.6

10.0.2.9 A.B.C.7.8.9

A

B

C

ARP operation: Caching ARP Table: A.B.C.7.8.9 – 10.0.2.9

IP IP MAC MAC A.B.C.1.2.3 A.B.C.7.8.9 10.0.2.1 10.0.2.9

Data

10.0.2.1 A.B.C.1.2.3

10.0.2.5 A.B.C.4.5.6

10.0.2.9 A.B.C.7.8.9

A

B

C

ARP: Local Destination

Internetwork communication

• How to communicate with devices that are not on the same physical network segment.

Default gateway

Default-Gateway

• •

•

In order for a device to communicate with another device on another network, you must supply it with a default gateway. A default gateway is the IP address of the interface on the router that connects to the network segment on which the source host is located. In order for a device to send data to the address of a device that is on another network segment, the source device sends the data to a default gateway.

Remote Destination

Packet forwarding • At layer 2, when encapsulating a frame, the host needs the destination MAC address • The host will then compares IP address of source and destination. – If the destination is on another network, then it will encapsulate the frame with the default-gateway MAC address. – If the destination is on the same net work, then it will use the destination MAC address

• Then it checks if the needed MAC address is in the ARP table, if it is not proceed ARP request to find the needed MAC address

Summary • • • • • • •

Four layers of TCP/IP model IP address, IP address classes Network address and broadcast address Public address and private address IPv4 versus IPv6 Static addressing, RARP, BOOTP, DHCP ARP local and remote destination