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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
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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 Scheme
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 CIM 2465 IP Addressing Scheme
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 Scheme
Address Assignment (2) • ipconfig CIM 2465 IP Addressing Scheme
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 Scheme
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 Scheme
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 CIM 2465 IP Addressing Scheme
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 Scheme
Network Classes (3) • Fig 9-15 CIM 2465 IP Addressing Scheme
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 CIM 2465 IP Addressing Scheme
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) CIM 2465 IP Addressing Scheme
Network Classes (6) • Fig 9-17 CIM 2465 IP Addressing Scheme
Number of Hosts per Network • Depends on number of bits of the Host part CIM 2465 IP Addressing Scheme
Number of Class A, B, C Networks • Depends on number of bits of the network part • How many class A? 28 ? 28 – 2 ? CIM 2465 IP Addressing Scheme
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 CIM 2465 IP Addressing Scheme
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 Scheme
Three subnets • IP addresses beginning with 10.1.1 • IP addresses beginning with 10.1.2 • IP addresses beginning with 10.1.3 CIM 2465 IP Addressing Scheme
Various Views of Subnetted IP Addresses • Fig 9-19 CIM 2465 IP Addressing Scheme
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 CIM 2465 IP Addressing Scheme
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 Scheme
Fig 9-20 CIM 2465 IP Addressing Scheme
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 Scheme
NAT and Private IP Networks (2) CIM 2465 IP Addressing Scheme
IPv4 Vs IPv6 CIM 2465 IP Addressing Scheme
Assigning and Mapping IP Addresses • A planning process • Two popular methods • Static IP Address Configuration • Dynamic configuration using (DHCP) CIM 2465 IP Addressing Scheme
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 Scheme
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 Scheme
Fig 9-25 CIM 2465 IP Addressing Scheme
DHCP Mechanism • Fig 9-26 CIM 2465 IP Addressing Scheme
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 Scheme
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 Scheme
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) CIM 2465 IP Addressing Scheme
ARP Process CIM 2465 IP Addressing Scheme
Using IP ARP in Larger Network CIM 2465 IP Addressing Scheme