Network Fundamentals

Network Fundamentals Chapter 6

Network Architecture • Network infrastructure involves the network’s physical configuration, logical operation, structure, procedures, data format, protocols and other components. • The most common forms of network architectures are Local Area Network (LAN) and Wide Area Network (WAN) • LAN’s are typically smaller in terms of size and geographic coverage and consist of two or more connected devices. Prepared by Saher Hasan Mohammed

Network Architecture • WAN’s tend to larger, covering more geographic area and consist of two or more systems in geographically separated areas connected by any of a variety of methods such as leased lines, radio waves, satellite relay, microwaves or even dial-up connection. Prepared by Saher Hasan Mohammed

Network Architecture • Campus Area Network (CAN): a network connecting any number of buildings in an office or university complex. • Metropolitan Area Network (MAN): a network designed for a specific geographic locality such as a town or a city. • Storage Area Network (SAN): a high speed network connecting a variety of storage devices such as a tape, RAID, optical drives, file servers and others. Prepared by Saher Hasan Mohammed

Network Architecture • Virtual Local Area Network (VLAN): a logical network allowing systems on different physical network to interact as if they were connected to the same physical network. • Client-Sever: A network where powerful, dedicated systems called servers provide resources to individuals workstations or clients. • Peer-to-Peer: a network where every system is treated as an equal, such as a home network. Prepared by Saher Hasan Mohammed

Network Architecture • Internet: a “global network” connecting thousands of millions of systems and users. • Intranet: a “private’ network only accessible to authorized users. Many large corporations host an intranet to facilitate information sharing within their organization. • Extranet: a “private” network established by connecting two or more intranets. This network is accessible only to the authorized users from the participating intranet’s. Prepared by Saher Hasan Mohammed

Network Topology • Network Topology: refers to the way the network is physically and logically arranged. • Star Topology: all the network components are connected to a central point. • Bus Topology: all the network components are connected to same cable, called the “bus” or the “backbone”. • Ring Topology: all the network components are connected to each other in a closed loop with each device directly connected to two other devices. Prepared by Saher Hasan Mohammed

Network Topology – Star Topology Client - PC Client Active Node Hub Client - PC Client - Laptop Client Client Client - Scanner Client - Printer Server Client Prepared by Saher Hasan Mohammed

Network Topology – Bus Topology Client Client Client Server Client Prepared by Saher Hasan Mohammed

Network Topology – Ring Topology Client Client Client Server Client Client Prepared by Saher Hasan Mohammed

Network Topology – Mixed Topology Client Client Client Client Client Client Server Server Client Client Client Client BUS Prepared by Saher Hasan Mohammed

Network Protocol • A protocol is an agreed upon format for exchanging or transmitting data between systems. • A protocol defines a number of agreed upon parameters, such as data compression methods, the type of error checking to use, and mechanism for systems to signal when they have finished either receiving or transmitting data. Prepared by Saher Hasan Mohammed

Network Protocol – Examples • Ethernet: the most widely used LAN protocol. • TCP/IP: the collection of communications protocols used to connect hosts to the internet. TCP/IP is the most widely used network protocol and is a combination of the TCP and IP. • Internet Protocol: the protocol for managing and transmitting data between packet-switched networks. • AppleTalk: the communication protocol developed by Apple to connect Macintosh computers and printers. Prepared by Saher Hasan Mohammed

Packets • The main purpose of communication networks is to facilitate the sharing of information. • Every network has some limitations on the amount of data that can be transmitted. • Larger chucks of data is broken down into smaller, more manageable sized chunks called packets. • Breaking down a large chunk of data into smaller size chunks has advantages, the network bandwidth is better utilized. In case of any transmission error, we do not have to retransmit one large large chuck data. Prepared by Saher Hasan Mohammed

IP Packet Fields • Protocol version number: what kind of packet it is. • Packet header length: how large the header of the packet is. • TOC: how to process the packet, i.e., minimize delay, maximize throughput, maximize reliability, and minimize cost. • Identification: an unique identifier so this packet can be distinguished from other packets. • Total length: how large the entire packet is. • Flag: Whether or not this packet is part of a longer data stream and should be handled relative to other packets. Prepared by Saher Hasan Mohammed

IP Packet Fields • Fragment offset: a description of where this packet fits into data stream as compared to other packets. • Checksum: checksum code to minimize the potential for data corruption during transmission. • Source IP: where the packet is from. • Destination IP: where the packet is going. • Data Payload: the data this packet carries. • Options: governs security and handling restrictions, whether or not to record the route this packet has taken. Prepared by Saher Hasan Mohammed

IP Packet Structure Prepared by Saher Hasan Mohammed

User Datagram Protocol – UDP • UDP is a “connectionless” protocol. • No connection is established between the sender and the receiver. • There is no way for the sender to know if the packet was successfully transmitted to the receiver, and in the order sent. • Since no connection is established, UDP is considered to be an unreliable protocol. • UDP is used when the loss of data is tolerated. • Advantage of UDP: most of the bandwidth is used for the transfer of data, there is no overhead. Prepared by Saher Hasan Mohammed

Transmission Control Protocol - TCP • TCP is a “connection-oriented” protocol. • Sender and the receiver establishes a connection via “three was handshake” before transmitting the data. • TCP is a reliable protocol, the packets are processed in the order sent. Each packet has a sequence number. Prepared by Saher Hasan Mohammed

Packet Delivery • The ultimate purpose of any communication network is to deliver packets across the networks. • Packets can be delivered locally, if the destination address belongs to a local network. Packets can be delivered remotely, if the destination address is belongs to a different network. Alternatively, the packets can be delivered remotely, then locally. • There are two types of packet delivery mechanisms. • Local Packet Delivery • Remote Packet Delivery Prepared by Saher Hasan Mohammed

Local Packet Delivery • If the source and the destination are on the same LAN, or a local network, local packet delivery is used. • Delivery is accomplished by using the MAC address. • Media Access Control (MAC) address is a system’s hardware address. Every system has a unique MAC address. • A MAC address is expressed as six pairs of hexadecimal digits such as 00:07:e9:7c:c8:aa. • Storing the MAC address of each system on the local LAN is impossible and time consuming. • To find the destination MAC address, the sending system must use Address Resolution Protocol (ARP). Prepared by Saher Hasan Mohammed

Local Packet Delivery • The sending system knows the destination IP address, however, it does not know the destination MAC address. • To know the destination MAC address, the sending system send a broadcast query to all the systems on the LAN asking “who is 10.1.1.140?” • Only the system with the 10.1.1.140 IP address will respond to the broadcast query by sending the MAC address. Prepared by Saher Hasan Mohammed

Remote Packet Delivery • Remote packet delivery is accomplished via IP address. • For humans, IP address are very difficult to remember. • Domain Name System (DNS) protocol was developed to translate a name into IP address. • Routers are used to interconnect different networks. The sending system send the packet to the router, the router will check its routing table to see where to resent the packet. This process is called routing. • This process is repeated until the packet reaches the destination router. The destination router fill finally determine the MAC address, and forward the packet to the destination. Prepared by Saher Hasan Mohammed

Subnet • IPv4 IP address has a network part and a host part. • The network part is called the subnet. • The process of dividing the 32 bit space into networks is called subnetting. • Subnet mask is used to tell exactly how much of the space is network portion and how much is the host portion. Prepared by Saher Hasan Mohammed

Subnet – Example • IP address 10.10.10.101 • Subnet mask: 255.255.255.0 • Convert the decimal format to binary format. • Subnet mask: 11111111.11111111.11111111.00000000 • IP address: 00001010. 00001010. 00001010. 01100101 • Perform a bitwise AND operation to get the subnet address. • Subnet Address: 00001010. 00001010. 00001010. 00000000 • Subnet Address in decimal format: 10.10.10.0 Prepared by Saher Hasan Mohammed

Subnet • Class A address: • Supports 16 million host address on each of 27 network. • Subnets: 10.10.10.0 to 126.255.255.255. • Class B address: • Supports 65,000 hosts on each of 16,000 networks. • Subnets: 128.0.0.0 to 192.255.255.255. • Class C address: • Supports 254 hosts on each of 2,000,000 networks. • Subnets: 192.0.0.0 to 223.255.255.255. Prepared by Saher Hasan Mohammed

Network Address Translation (NAT) • NAT translate the private (non-routable) IP address into public (routable) IP address. • Most organization use private IP address for internal usage, and use a NAT device to translate many internal IP address into small number of public IP address. Prepared by Saher Hasan Mohammed

Network Address Translation (NAT) Outbound Source: 10.10.10.121 Destination: 207.25.71.23 Source: 63.69.110.110 Destination: 207.25.71.23 www.hotmail.com 207.25.71.23 Firewall Performing NAT Source : 207.25.71.23 Destination: 63.69.110.110 Source : 207.25.71.23 Destination: 10.10.10.121 Internal Network Inbound Prepared by Saher Hasan Mohammed

Network Fundamentals