Transcript Slide 1
IPv4 and Subnetting CIDR notation Address class is no longer uniquely identifiable from the address We must find a way of telling routers the size of the network part of the address Done by including a number along with the network address E.g. 73.5.0.0/ 17 • In the above example, the first 17 bits of the address are the network part • You can search for more example CIDR address blocks at http://www.arin.net CIDR notation The CIDR notation will tell you how many IP addresses are available in that subnet. How does a company allocate a large pool of addresses? Ex. UNCW has 152.20.0.0 / 16 which gives them a possible 65,536 IP addresses (2(32-16)) Possible approach to assigning IP addresses: As soon as a computer comes online, you can assign them the next IP address available. Workstation in Library Desktop in CIS Laptop in Union 5-4 How does a company allocate a large pool of addresses? Alternative Method: Each college or building allocated a contiguous set of IP addresses Fisher Union 152.20.2.0 152.20.2.255 Library 152.20.3.0 152.20.3.255 CIS 152.20.1.0 152.20.1.255 Laptop in Union Desktop in CIS Workstation in Library 5-5 Subnetting and network structure Each Ethernet is given a unique subnetwork ID Enables broadcasting within the Ethernet Each computer on the Ethernet must be part of this network Subnetting enables the partition of a large address pool into multiple smaller blocks Hospital Ethernet University campus Library Ethernet Hospital subnet 131.247.5.0 – 131.247.5.255 Library subnet 131.247.1.0 – 131.247.1.255 Cisco 3600 SERIES 0 1 1 ACTIVE 0 READY SYSTEM COM RPS PCMCIA AUX Main campus router Business School Ethernet Business school subnet 131.247.2.0 – 131.247.4.255 Engineering Ethernet Engineering subnet 131.247.6.0 – 131.247.7.255 Subnets and IP Addresses Network part of IP address Host part of IP address 10000011 11110111 00010000 11101011 131 . 247 . Network ID (USF) 16 . 235 Host ID (worskstation 24 in lab) What does UNCW’s IP Addresses look like? 3-part interpretation of IP addresses Network part of IP address 10000011 11110111 00010000 11101011 131 . 247 . Network ID (USF) 16 . 235 Subnet ID Host ID (College of (worskstation 24 in Business) lab) Host part of IP address Subnet ID component of host part of IP address Host ID component of host part of IP address 8 Subnets - How do you decide who gets what address? Group of computers on the same LAN with IP numbers using the same prefix Assigned addresses For example: • Subnet 152.20.234.x – Computers in CIS labs (x is between 0 & 255) • Subnet 152.20.244.x & 152.20.196.x – Computers in CIS Offices (x is between 0 & 255) • Subnet 129.79.125.x – Computers in Cameron Does anyone see a problem with the subnets above? 5-9 Subnet: Example Address: 152.20.244.254 Address: 172.20.104.254 Address: 152.20.5.56 CIS R 152.20.244.X 172.20.101.X Library R 172.20.104.X R Address: 152.20.5.70 Cameron 172.20.102.X R Psych R 172.20.103.X Campus Backbone Address: 152.20.5.X 5 - 10 Basic Subnetting How do we create 2 subnets? 5 - 11 Basic Subnetting How do we create 3 subnets? 5 - 12 Basic Subnetting How do we create 4 subnets? 5 - 13 Subnetting example Consider an organization with a /16 network address block (131.247.0.0/ 16) Most medium-large organizations fall in this category Also, most State Universities Say, after analysis, the organization settles on 5-bit subnet IDs Example with 5-bit subnet IDs Subnet ID Campus unit Subnet ID Campus unit Subnet ID Campus unit 00001 (1) College 1 00010 (2) College 2 00011 (3) College 3 00100 (4) College 4 00101 (5) College 5 00110 (6) College 6 00111 (7) College 7 01000 (8) College 8 01001 (9) College 9 01010 (10) College 10 01011 (11) <future college> 01100 (12) <future college> 01101 (13) Dorm 1 01110 (14) Dorm 2 01111 (15) <future dorm> 10000 (16) <future dorm> 10001 (17) Branch campus 1 10010 (18) Branch campus 2 10011 (19) <future branch campus > <future expansion> <future expansion> <future expansion> 10100 (20) Administration 10101 (21) Campus IT 10111 (23) <future expansion> <future expansion> <future expansion> 11000 (24) <future expansion> <future expansion> <future expansion> 10110 (22) 11001 (25) 11100 (28) 11010 (26) 11101 (29) 11011 (27) 11110 (30) Network ID + subnet ID for colleges in example Campus unit Subnet ID First 2 parts of IP addresses by college College 1 00001 10000011.11110111.00001_ _ _ . _ _ _ _ _ _ _ _ College 2 00010 10000011.11110111.00010 _ _ _ . _ _ _ _ _ _ _ _ College 3 00011 10000011.11110111.00011 _ _ _ . _ _ _ _ _ _ _ _ College 4 00100 10000011.11110111.00100 _ _ _ . _ _ _ _ _ _ _ _ College 5 00101 10000011.11110111.00101 _ _ _ . _ _ _ _ _ _ _ _ College 6 00110 10000011.11110111.00110 _ _ _ . _ _ _ _ _ _ _ _ College 7 00111 10000011.11110111.00111 _ _ _ . _ _ _ _ _ _ _ _ College 8 01000 10000011.11110111.01000 _ _ _ . _ _ _ _ _ _ _ _ College 9 01001 10000011.11110111.01001 _ _ _ . _ _ _ _ _ _ _ _ College 10 01010 10000011.11110111.01010 _ _ _ . _ _ _ _ _ _ _ _ Complete subnet addresses for colleges in example Campus unit Subnet address (binary) Subnet address (decimal) College 1 10000011.11110111.00001000.00000000 131.247.8.0/ 21 College 2 10000011.11110111.00010000.00000000 131.247.16.0/ 21 College 3 10000011.11110111.00011000.00000000 131.247.24.0/ 21 College 4 10000011.11110111.00100000.00000000 131.247.32.0/ 21 College 5 10000011.11110111.00101000.00000000 131.247.40.0/ 21 College 6 10000011.11110111.00110000.00000000 131.247.48.0/ 21 College 7 10000011.11110111.00111000.00000000 131.247.56.0/ 21 College 8 10000011.11110111.01000000.00000000 131.247.64.0/ 21 College 9 10000011.11110111.01001000.00000000 131.247.72.0/ 21 College 10 10000011.11110111.01010000.00000000 131.247.80.0/ 21 Subnet Masks Used to make it easier to separate the subnet part of the address from the host part. Example Subnet: 149.61.10.x Subnet mask: 255.255.255.000 or in binary 11111111.11111111.11111111.00000000 Example Subnets: 149.61.10.1-128, Subnet mask 255.255.255.128 or, in binary: 11111111.11111111.11111111.10000000 5 - 18 Subnet mask operation What does a subnet mask do? The 0’s in the subnet mask block (mask) the corresponding bits in any destination address The 1’s in the subnet mask allow the corresponding bits to be seen The Result is the subnet address How a network is setup for IP addresses Determine the Total Number of Hosts 5 - 20 How a network is setup for IP addresses Determine the Number and Size of the Networks 5 - 21 How a network is setup for IP addresses Allocating Addresses 5 - 22 How a network is setup for IP addresses Allocating Addresses 5 - 23 How a network is setup for IP addresses Within the address range of each IPv4 network, we have three types of addresses: • Network address - The address by which we refer to the network • Broadcast address - A special address used to send data to all hosts in the network • Host addresses - The addresses assigned to the end devices in the network 5 - 24 Case study – networks in the retail sector Both Wal-Mart and K-Mart started in 1962 K-Mart grew rapidly at first 250 stores in 1967, compared to 18 Wal-Marts Each K-Mart store had 6 times the revenue of a Wal-Mart store 2002 K-Mart filed for bankruptcy For the first time, Wal-Mart was the largest company in America by revenue Among other factors Wal-Mart relied on IT First computer network using phone lines in 1977 • To improve inventory refills Satellite network in 1987 • Cut credit card processing time by half EDI, RetailLink K-Mart relied on managerial expertise Used spreadsheets to track supply and demand