CIM 2465 IP Addressing Scheme1 IP Addressing Scheme (Topic 4) Textbook: Networking Basics, CCNA 1...

CIM 2465 IP Addressing Scheme 1

IP Addressing Scheme(Topic 4)

Textbook:

Networking Basics, CCNA 1 Companion Guide, Cisco Press

Cisco Networking Academy Program, CCNA 1 and 2, Companion Guide, Cisco Press, Latest Edition


IP Address Fundamentals

• Logical address

• IPv4 (32 bits, usually in dotted-decimal, e.g. 192.168.123.1)

• Must be unique inside a particular network


Address Assignment (1)• All hosts on the same LAN must use the same

value for the first part of their IP addresses (length depends on size of the network)

• IP addresses are assigned to network interfaces rather than to entire computers


Address Assignment (2)

• ipconfig


Address Assignment (3)

• 3 key rules– Devices on the same LAN must use IP addres

ses in the same group (IP network)– Devices on different LANs that are separated

by at least one router must use IP addresses in different IP networks

– IP addresses must be unique inside the same internetwork

• Fig 9-13


• Three networks– All IP addresses that begin with 10– All IP addresses that begin with 11– All IP addresses that begin with 12


Network Classes (1)• Unicast IP address

– An IP address that can be assigned to a single interface• IPv4 defines 3 three classes of unicast IP addresses, determined b

y the value of the first octet of the address• An address includes two parts (no subnetting)

– network part– host part

Range of values

In first octet

Class Length of Network Part

Length of Host Part

1-126 A 1 octet 3 octets

128-191 B 2 octets 2 octets

192-223 C 3 octets 1 octet


Network Classes (2)

• Fig 9-14

• A unicast IP address determines its class and structure, specifically, the size of the network and host parts of the address

• An IP network consists of all unicast IP addresses for which the network part’s value is the same


Network Classes (3)

• Fig 9-15

IP Address Class Network part Host part

10.1.1.1

172.22.3.4

192.168.55.66


Network Classes (4)

• IPv4 uses class D IP addresses to multicast packets to a multicast destination IP address (all hosts will receive a copy of the packet)

• Table 9-7

• Values of 0 and 127 are not listed in the first octet– 127.0.0.1, loopback IP address– Network 0.0.0.0 has been reserved


Network Classes (5)

• IP network number (network ID) is a dotted-decimal number that represents a particular IP network. E.g. 10.0.0.0

• First and last number in a network are reserved– 10.0.0.0 (network ID)

– 10.255.255.255 (network broadcast address)

IP Address Class Network address Host address

10.1.1.1

172.22.3.4

192.168.55.66


Network Classes (6)

• Fig 9-17


Number of Hosts per Network

• Depends on number of bits of the Host part

Class Network part (bits)

Host part (bits)

Number of Hosts per Network

A

B

C


Number of Class A, B, C Networks

• Depends on number of bits of the network part• How many class A? 28 ? 28 – 2 ?

Class Network part (bits)

“Fixed” bits at beginning

Bits that can vary

Number of Networks

A

B

C


Subnetting (1)

• Subnetting allows the network designer to subdivide a classful IP network into smaller groups, called subnets

• Class A network 10.0.0.0, was divided into three subnets– 10.1.1– 10.1.2– 10.1.3


Subnetting (2)

• Key rules– Devices on the same LAN must use IP addresses in t

he same group (IP subnet)– Devices on different LANs that are separated by at le

ast one router must use IP addresses in different IP subnet

– IP addresses must be unique inside the same internetwork

• Subnet: A group of IP addresses that all have the same value in the first part of the address

• Subnet number: A dotted-decimal number that represents a particular IP subnet


• Three subnets– IP addresses beginning with 10.1.1– IP addresses beginning with 10.1.2– IP addresses beginning with 10.1.3


Various Views of Subnetted IP Addresses

• Fig 9-19


Subnet Mask

• To find out the network (and subnet) parts of an IP address, thus determine whether two hosts are in the same network

• To determine if the network is subnetted

IP Address Mask Class Network Subnet Host

10.1.2.3 255.0.0.0

172.22.109.4 255.255.0.0

192.168.1.109 255.255.255.0

10.1.2.3 255.255.0.0

172.22.109.4 255.255.224.0

192.168.1.109 255.255.255.224


Ensuring Unique IP Addresses Throughout the Internet

• Unique IP addresses on all computers?

• Unique Network Address for Each Enterprise Network

• Internet Assigned Numbers Authority (IANA), IANA member organizations

• IPv4 Address Depletion– NAT, Private IP Networks– IPv6 (128 bits)


• Fig 9-20


NAT and Private IP Networks (1)

• NAT allows a company to use just a few registered IP addresses instead of an entire registered Class A, B, or C networks

• Fig 9-21


NAT and Private IP Networks (2)

Class Range of Network Numbers

Total Number of Networks

A 10.0.0.0 1

B 172.16.0.0 – 172.31.0.0 16

C 192.168.0.0 – 192.168.255.0

256


IPv4 Vs IPv6


Assigning and Mapping IP Addresses

• A planning process

• Two popular methods– Static IP Address Configuration– Dynamic configuration using (DHCP)


Static IP Address Configuration

• Fixed IP addresses entered by users• Key Config Options

– IP address, Subnet mask, Default gateway, DNS server

• Fig 9-23


Dynamic IP Config Using DHCP

• Dynamic Host Configuration Protocol (DHCP)• DHCP allows a host that does not have a static

IP address configured on an interface to send a request to a DHCP server

• The server then sends back a DHCP reply (IP address that can be used, mask, default gateway, and DNS server, and other control information)


• Fig 9-25


DHCP Mechanism

• Fig 9-26


Advantages of using DHCP

• When companies move employees and their PCs, the PCs can be installed in the new offices, send a DHCP request, and be up and running

• Laptop computers can be moved all over a network (company, home, hotel…)

• DHCP server can keep statistics of the usage of IP addresses

• DHCP reclaims the IP address once the lease expires so another host can use the IP addresses


Why use Static IP

• Server IP addresses need to stay the same

• Routers, switches need to stay at the same IP addresses

• End-user hosts do not move often

• Network administration


Using ARP

• For an IP host to send an IP packet over a LAN, the sending host must know the Ethernet MAC address of another device on the LAN

• By Address Resolution Protocol (ARP)


ARP Process


Using IP ARP in Larger Network

CIM 2465 IP Addressing Scheme1 IP Addressing Scheme (Topic 4) Textbook: Networking Basics, CCNA 1...

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