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Unit 1 Network layer and protocols, , 1.1, , IP addressing :, Ip address is a unique address that identifies a device on internet or local network., It is identifier that allows information to be sent between devices on a network. IP, addressing is the method used to identify hosts and network devices. The number of hosts, connected to the internet continues to grow and the IP addressing scheme has been adapted, over a time., 1. Network ID (Network address):, Identifies the network on which a host computer can be found., 2. Host ID (or Host address):, Identifies a specific device on the network indicated by the network ID., , 32bit, Network ID, , Host ID, , Fig. Parts of IP Address., , 145.25.10.100, Network ID, , Host ID, , Fig. Example of an IP address, Address space:, Address space is the amount of memory allocated for all possible addresses for a, computational entity, such as a device, a file, a server, or a networked computer. A protocol, IPv4 that defines address has an address space. IP uses 32-bit address, which means that, the address space is 232 or 4,294,967(more than Billions).
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Notations:, CIDR (Classless Inter Domain Routing) notation is a compact representation of an, IP address and its associated network mask. The notation was invented by Phil Karn in the, 1980s. CIDR notation specifies an IP address, a slash ('/') character, and a decimal number., e.g. A short list of things to do., , Classfull Addressing:, Classfull addressing is an IPv4 addressing architecture that divides addresses into, five groups (A, B, C, D, E). Prior to classful addressing, the first eight bits of an IP address, defined the network a given host was a part of. This would have had the effect of limiting, the internet to just 254 networks. It has three-part view, the address has an 8,16,24bit, network field based on the class A, B and C addressing rules., , Fig. Classfull Addressing
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Classless Addressing:, Classless Addressing is an improved IP Addressing system. It makes the allocation, of IP Addresses more efficient. It replaces the older classful addressing system based on, classes. It is also known as Classless Inter Domain Routing (CIDR). It uses a two part view, of IP address., Subnetting:, A subnet, or subnetwork, is a segmented piece of a larger network. More, specifically, subnets are a logical partition of an IP network into multiple, smaller network, segments. The Internet Protocol (IP) is the method for sending data from one computer to, another over the internet. Each computer, or host, on the internet has at least one IP address, as a unique identifier., Organizations will use a subnet to subdivide large networks into smaller, more, efficient subnetworks. One goal of a subnet is to split a large network into a grouping of, smaller, interconnected networks to help minimize traffic. This way, traffic doesn't have to, flow through unnecessary routs, increasing network speeds., An IP address is divided into two fields: a Network Prefix (also called the Network, ID) and a Host ID. What separates the Network Prefix and the Host ID depends on whether, the address is a Class A, B or C address., Supernetting:, Supernetting is the opposite of Subnetting. In subnetting, a single big network is, divided into multiple smaller subnetworks. In Supernetting, multiple networks are, combined into a bigger network termed as a Supernetwork or Supernet. Supernetting is, mainly used in Route Summarization, where routes to multiple networks with similar, network prefixes are combined into a single routing entry, with the routing entry pointing, to a Super network, encompassing all the networks. This in turn significantly reduces the, size of routing tables and also the size of routing updates exchanged by routing protocols., , How to supernet a network? Combining these networks into one network:
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(A summarized route), • 192.168.0.0/24, • 192.168.1.0/24, • 192.168.2.0/24, • 192.168.3.0/24, Step 1:, Write all the IP Addresses in binary like so:, • 192.168.0.0/24, 11000000.10101000.00000000.00000000, • 192.168.1.0/24, 11000000.10101000.00000001.00000000, • 192.168.2.0/24, 11000000.10101000.00000010.00000000, • 192.168.3.0/24, 11000000.10101000.00000011.00000000, Step 2:, Find matching bits from left to right, 11000000.10101000.00000000.00000000, 11000000.10101000.00000001.00000000, 11000000.10101000.00000010.00000000, 11000000.10101000.00000011.00000000, Step 3:, Re write the matching numbers and add the remaining zeros, because you are, converting network bits into host bits. This will be your NEW NETWORK ID, the route, that you will be advertising., (A summarized route), 11000000.10101000.00000000.00000000 = 192.168.0.0, Step 4:, Find the new subnet mask. Put “1s” in the matching networking part, and all zeros, in the host part. 11111111.11111111.11111100.00000000 This your new subnet mask, 255.255.252.0
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• Your new summarized route is 192.168.0.0/22, , Network Address Translation (NAT):, Network Address Translation (NAT) is a process in which one or more local IP, address(Private) is translated into one or more Global IP address (Public) and vice versa in, order to provide Internet access to the local host.When a packet enters the local network, the global IP address is converted to a local IP address and Viceversa., , 1.2, , Internet Protocol:, The Internet Protocol (IP) is a protocol that contains addressing information and, some control information that enables packets to be routed. IP information is attached to, each packet and this information helps routers to send packets to the right place., Datagram Format:, Data transmitted over an internet using IP is carried in message called IP datagrams.The, , format of data that can be recognized by IP is called an IP datagram. It consists of two, components, namely, the header and data, which need to be transmitted. Every field in the IP, datagram has a fixed size except for the IP Options field, which can be 20–60 bytes in length.
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Fragmentation:, IP fragmentation is an Internet Protocol (IP) process that breaks packets into smaller pieces, (fragments), so that the resulting pieces can pass through a link with a smaller maximum, transmission unit (MTU) than the original packet size. The fragments are reassembled by the, receiving host, The example of the IP packet fragmentation for IPv4 Original packet which size is 5140, bytes is divided into four fragments of maximum 1500 bytes. If one fragment of an IP packet is, dropped, then the entire original IP packet must be resent (all fragments)., , Fig. Example of fragmentation of a PDU in a given layer into smaller units.
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Options:, The Internet Protocol (IP) has provision for optional header fields identified by an option, type field. Options 0 and 1 are exactly one octet which is their type field. ... These taken together, form an eight bit value for the option type field. IP options are commonly referred to by this value., 1.3, , ICMPv4, ICMPv4 protocol is a network layer protocol. ICMPv4 protocol is an error reporting, protocol and it reports an error that occurs while IP datagram travels from source host to, the destination host. ICMPv4 is a message-oriented protocol which is used in assistance, with IP protocol as IP protocol lack in error reporting., , Fig. ICMP Message Format, Messages:, A communication sent by one user to another user by means of an e-mail system, such as the Simple Mail Transfer Protocol (SMTP) mail system that is used over the, Internet. A message can contain either text or binary data.
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Error Reporting:, Error Reporting reports the problems that any Host encounter while they are, processing a packet., , Query Messages:, Query Messages help to host or router to get specific information about another, host., , Debugging Tools:, Debugging tools (called debuggers) are used to identify coding errors at various, development stages. They are used to reproduce the conditions in which error has occurred,, then examine the program state at that time and locate the cause., , ICMP Checksum:, The Internet Control Message Protocol (ICMP) is a supporting protocol in, the Internet protocol suite. It is used by network devices, including routers, to send error, messages and operational information indicating success or failure when communicating, with another IP address, for example, an error is indicated when a requested service is not, available or that a host or router could not be reached., , 1.4, , Mobile IP:, Mobile, , IP, , is, , an, , Internet, , Engineering, , Task, , Force, , (IETF), , standard, , communications protocol that is designed to allow mobile device users to move from one, network to another while maintaining their permanent IP address., , Addressing:, The main Problem that must be solved by providing mobile Communication using the IP, Protocol is called as Addressing.
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Agents:, a computer program that performs various actions continuously and autonomously on, behalf of an individual or an organization. For example, an agent may archive various, computer files or retrieve electronic messages on a regular schedule., , Three Phases:, 1.Agent Discovery:, A mobile nude Discovers its foreign and home agent during agents discovery., A mobile node uses a method known as agent discovery to determine the following, information:, •, , When the node has moved from one network to another, , •, , Whether the network is the node's home or a foreign network, , •, , What is the foreign agent care-of address offered by each foreign agent on that network, , 2. Registration:, The Mobile Node registers its current location with the foreign agent and home agent, during registration. Mobile IP registration provides a flexible mechanism for mobile nodes, to communicate their current reachability information to their home agent. The registration, process enables mobile nodes to perform the following tasks: Request forwarding services, when visiting a foreign network., , 3. Tunneling:, A reciprocal tunnel is set up by the home agent to the care of address(current location of, the mobile node on the foreign network) to rout packets to the mobile node as it romas., e Mobile Node sends packets using its home IP address, effectively maintaining the, appearance that it is always on its home network. Data packets addressed to the Mobile, Node are routed to its home network, where the Home Agent now intercepts and tunnels, them to the care-of address toward the Mobile Node.
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Inefficiency:, , The degree of the inefficiency of Mobile IP is a function of the internetwork distance, between device A and M's home network, compared to the internetwork distance between, device A and M's current network., , 1.5, , Virtual Private Network (VPN):, A virtual private network, or VPN, is an encrypted connection over the Internet from a, device to a network. The encrypted connection helps ensure that sensitive data is safely, transmitted. It prevents unauthorized people from eavesdropping on the traffic and allows, the user to conduct work remotely. VPN technology is widely used in corporate, environments., •, , A VPN or virtual private network, is a secure tunnel between your device and the, internet. Or, , •, , Between two private networks connected on internet.
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Virtual Private networks extends a private network across a public network and, enables users to send and receive data across shared or public network as if their computing, devices were directly connected to the private network VPN increases a security and, management of the private network.
