ASHWIN JADHAV BANDER AL TURAIF KALYAN MANTRAVADI PRAVEEN GADIKOTA INTRODUCTION The first computer networks were designed with the hardware as the main concern Idea of software controlled mechanisms To reduce the design complexity most networks were organized as a series of levels or layers each one built upon the one below it Hardware is considered to be a bottleneck but by improving network software can overcome some of the hardware limitations Earlier the ISO OSI architecture was used INTRODUCTION To provide communication amongst various network infrastructures the TCP IP reference model was proposed with the TCP IP protocol suite as the protocol stack The requirement led to the choice of a packet switching network based on a connectionless internet work layer Its job is to inject packets into any network and have them travel independently to the destination The network layer is the lowest layer that deals with endto end communication The internet layer defines an official packet format and protocol called IP Internet Protocol TCP IP vs OSI Model Internet Protocol The protocols and technologies work as a team to accomplish the goal of communication across the network Like any team no single member can get the job done alone no matter how good they are Still if we were to try to pick a most valuable player in the world of networking a good case could be made that we have it here in this section the TCP IP Internet Protocol IP IP is in fact the workhorse of TCP IP It implements key network layer functions including addressing datagram handling and routing and is the foundation upon which other TCP IP protocols are built IP Overview The Internet Protocol IP is the core of the TCP IP protocol suite The network layer is primarily concerned with the delivery of data between devices that may be on different networks that are interconnected in an arbitrary manner IP is the mechanism by which this data is sent on TCP IP networks Key Concept While the Internet Protocol has many functions and characteristics it can be boiled down to one primary purpose the delivery of datagram s across an internetwork of connected networks Key IP Characteristics The Internet Protocol is said to be Universally Addressed Underlying Protocol Independent Delivered Connectionlessly Delivered Unreliably Delivered Without Acknowledgments IP Functions Addressing Data Encapsulation and Formatting Packaging Routing algorithms congestion control algorithms and optimization techniques Fragmentation and Reassembly Routing Indirect Delivery Internet Protocol Version 4 IP IPv4 Version 4 of IP was the first widely used in modern TCP IP It provides the basic datagram delivery capabilities upon which all of TCP IP functions and it has proven its quality in use over a period of more than two decades Defined in RFC 791 IPv4 HEADER FORMAT IP Addressing The primary job of IP is delivering messages between devices One of the most important functions of the Internet Protocol is addressing IP addresses are used not only to uniquely identify IP addresses but to facilitate the routing of IP datagram s over internetworks IP Addressing Overview IP Address Functions Identification and Routing Network Interface Identification IP address provides unique identification of the interface between a device and the network This is required to ensure that the datagram is delivered to the correct recipients Routing When the source and destination of an IP datagram are not on the same network the datagram must be delivered indirectly using intermediate systems a process called routing The IP address is an essential part of the system used to route datagram s IP Addressing Overview Number of IP Addresses Per Device Any device that has data sent to it at the network layer will have at least one IP address one per network interface Normal hosts such as computers and network capable printers usually get one IP address while routers get more than one IP address Lower level network interconnection devices such as repeaters bridges and switches don t require an IP address because they pass traffic based on layer two data link layer addresses contd IP Addressing Overview contd Address Uniqueness Network Specificity of IP Addresses Contrasting IP Addresses and Data Link Layer Addresses IP Addressing Overview IP Address Datagram Delivery Issues contd Private and Public IP Network Addresses IP Address Configuration static configuration dynamic configuration Key Concept IP addresses serve the dual function of device identification and routing Each network interface requires one IP address which is network specific IP addresses can be either statically or dynamically allocated and come in unicast multicast and broadcast forms IP Address Size The IP address is just a 32 bit binary number a set of 32 ones or zeroes At the lowest levels computers always work in binary and this also applies to networking hardware and software The address itself is just this 32 digit binary number IPIP Address Dotted Decimal addresses are normally expressed with each octet of 8 bits converted to a decimal number and the octets separatedNotation by a period a dot The lowest value is theoretically 0 0 0 0 and the highest is value is theoretically 0 0 0 0 and the highest is 255 255 255 255 Dotted decimal notation provides a convenient way to work with IP addresses The binary hexadecimal and decimal representations of an IP address are all equivalent IP Address Space The IP address is 32 bits wide the theoretical address space of 232 or 4 294 967 296 addresses Despite this IP was originally created on a rather small internetwork wasting much of the address space Just this one decision makes 1 256th of the total number of addresses or 16 277 216 addresses no longer available IP address space dictates the limit on the number of addressable interfaces in each IP internetwork So if you have a private network you can in theory have 4 billion plus addresses However in a public network such as the Internet all devices must share the available address space Techniques such as CIDR supernetting and Network Address Translation NAT were designed in part to more efficiently utilize the existing Internet IP address space Network ID and Host ID Internet IP Address Structure Even though these sets of 32 bits are considered a single entity they have an internal structure containing two components Network Identifier Network ID A certain number of bits starting from the left most bit is used to
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