International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-5, Issue-4, April 2016 242 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Pvt. Ltd. Computer Network - IP Address & Subnetting Rajesh Kumar, Pinky Ramchandra Shinde Abstract: The next-generation Internet Protocol, initially known as IP Next Generation (Ipng), and then later as IPv6, has been developed by the Internet Engineering Task Force (IETF) to replace the current Internet Protocol (also known as IPv4). which offers 2128 possible addresses To enable the integration of IPv6 into current networks, several transition mechanisms have been proposed by the IETF IPng Transition Working Group. This work examines and empirically evaluates two transition mechanisms, namely IPv6 to IPv4 tunneling and dual-stack mechanism, as they relate to the performance of IPv6. The primary focus of this paper is to compare and analyze IPv4 and IPv6 networks, study their characteristics and header formats. The paper also attempts to outline the key deployment issues and security-related challenges which are being faced and dealt with during the migration process. Keywords— IP address, Subnet, IPV4, IPV6, Multicast Address, Unicast Address, 6-over-4, encapsulation, tunneling, I. INTRODUCTION An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing . Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there." The rapid explosion of the internet and existence of high speed wireless and broadband networks have contributed towards depletion of IPv4.The IPv4 protocol created more than three decades ago with approximately an address space of 4 billion cannot cater to the needs of modern internet. The IANA (Internet Assigned Numbers Authority) allocated the last chunk of IPv4 addresses on Feb 3, 2011 to the Regional Internet Registries announcing end of IPv4 addresses [1]. The address depletion has posed a serious problem on the growth of internetworks. The short term solutions like PPP/DHCP (address sharing), CIDR (classless inter-domain routing) and NAT (network address translation) do not seem to help considering the number of devices that are getting connected to the internet daily. Also as the protocol was developed long time back, the features related to mobility, security and QoS (Quality of Service) are handled by additional protocols which cannot be integrated within the protocol. II. IP ADDRESS As we know that an Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, Revised Version Manuscript Received on May 02, 2016. Rajesh Kumar, Senior Lecturer, Department of Computer Science and Engineering, Govt. Polytechnic College, Ujjain – 456001 (M.P.). India. Ms. Pinky Ramchandra Shinde, Assistant Professor, Department of Computer, New Horizon Institute of Management Studies, Sector -13, Airoli, Navi Mumbai, India. Printer) participating in a computer network that uses the Internet Protocol for communication. There are 5 classes of IP address. “Class A” blocks (2 24 addresses, approximately 16.7 million). “Class B” (2 16 ) and “C” blocks (2 8 ) were provided to smaller networks. Early network architecture permitted only these three sizes. A. Class A Address The first bit of the first octet is always set to 0 (zero). Thus the first octet ranges from 1 – 127, i.e. Class A addresses only include IP starting from 1.x.x.x to 126.x.x.x only. The IP range 127.x.x.x is reserved for loopback IP addresses. The default subnet mask for Class A IP address is 255.0.0.0 which implies that Class A addressing can have 126 networks (2 7 -2) and 16777214 hosts (2 24 -2). Class A IP address format is thus: 0NNNNNNN.HHHHHHHH.HHHHHHHH.HHHHHHHH B. Class B Address An IP address which belongs to class B has the first two bits in the first octet set to 10, i.e. Class B IP Addresses range from 128.0.x.x to 191.255.x.x. The default subnet mask for Class B is 255.255.x.x.Class B has 16384 (2 14 ) Network addresses and 65534 (2 16 -2) Host addresses. Class B IP address format is: 10NNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH C. Class C Address The first octet of Class C IP address has its first 3 bits set to 110, that is: Class C IP addresses range from 192.0.0.x to 223.255.255.x. The default subnet mask for Class C is 255.255.255.x.Class C gives 2097152 (2 21 ) Network addresses and 254 (2 8 -2) Host addresses. Class C IP address format is: 110NNNNN.NNNNNNNN.NNNNNNNN.HHHHHHHH D. Class D Address Very first four bits of the first octet in Class D IP addresses are set to 1110, giving a range of: