CIM 2465 IP Addressing Scheme1 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

CIM 2465 IP Addressing Scheme2 IP Address Fundamentals Logical address IPv4 (32 bits, usually in dotted-decimal, e.g ) Must be unique inside a particular network

CIM 2465 IP Addressing Scheme3 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

CIM 2465 IP Addressing Scheme4 Address Assignment (2) ipconfig

CIM 2465 IP Addressing Scheme5 Address Assignment (3) 3 key rules –Devices on the same LAN must use IP addresses 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

CIM 2465 IP Addressing Scheme6 Three networks –All IP addresses that begin with 10 –All IP addresses that begin with 11 –All IP addresses that begin with 12

CIM 2465 IP Addressing Scheme7 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 by 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 ClassLength of Network Part Length of Host Part 1-126A1 octet3 octets B2 octets C3 octets1 octet

CIM 2465 IP Addressing Scheme8 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

CIM 2465 IP Addressing Scheme9 Network Classes (3) Fig 9-15 IP AddressClassNetwork partHost part

CIM 2465 IP Addressing Scheme10 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 – , loopback IP address –Network has been reserved

CIM 2465 IP Addressing Scheme11 Network Classes (5) IP network number (network ID) is a dotted-decimal number that represents a particular IP network. E.g First and last number in a network are reserved – (network ID) – (network broadcast address) IP AddressClassNetwork addressHost address

CIM 2465 IP Addressing Scheme12 Network Classes (6) Fig 9-17

CIM 2465 IP Addressing Scheme13 Number of Hosts per Network Depends on number of bits of the Host part ClassNetwork part (bits) Host part (bits) Number of Hosts per Network A B C

CIM 2465 IP Addressing Scheme14 Number of Class A, B, C Networks Depends on number of bits of the network part How many class A? 2 8 ? 2 8 – 2 ? ClassNetwork part (bits) “Fixed” bits at beginning Bits that can vary Number of Networks A B C

CIM 2465 IP Addressing Scheme15 Subnetting (1) Subnetting allows the network designer to subdivide a classful IP network into smaller groups, called subnets Class A network , was divided into three subnets – – –10.1.3

CIM 2465 IP Addressing Scheme16 Subnetting (2) Key rules –Devices on the same LAN must use IP addresses in the same group (IP subnet) –Devices on different LANs that are separated by at least 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

CIM 2465 IP Addressing Scheme17 Three subnets –IP addresses beginning with –IP addresses beginning with –IP addresses beginning with

CIM 2465 IP Addressing Scheme18 Various Views of Subnetted IP Addresses Fig 9-19

CIM 2465 IP Addressing Scheme19 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 AddressMaskClassNetworkSubnetHost

CIM 2465 IP Addressing Scheme20 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)

CIM 2465 IP Addressing Scheme21 Fig 9-20

CIM 2465 IP Addressing Scheme22 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

CIM 2465 IP Addressing Scheme23 NAT and Private IP Networks (2) ClassRange of Network Numbers Total Number of Networks A B – C –

CIM 2465 IP Addressing Scheme24 IPv4 Vs IPv6

CIM 2465 IP Addressing Scheme25 Assigning and Mapping IP Addresses A planning process Two popular methods –Static IP Address Configuration –Dynamic configuration using (DHCP)

CIM 2465 IP Addressing Scheme26 Static IP Address Configuration Fixed IP addresses entered by users Key Config Options –IP address, Subnet mask, Default gateway, DNS server Fig 9-23

CIM 2465 IP Addressing Scheme27

CIM 2465 IP Addressing Scheme28 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)

CIM 2465 IP Addressing Scheme29 Fig 9-25

CIM 2465 IP Addressing Scheme30 DHCP Mechanism Fig 9-26

CIM 2465 IP Addressing Scheme31 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

CIM 2465 IP Addressing Scheme32 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

CIM 2465 IP Addressing Scheme33 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)

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CIM 2465 IP Addressing Scheme35 ARP Process

CIM 2465 IP Addressing Scheme36 Using IP ARP in Larger Network

CIM 2465 IP Addressing Scheme37