Internet Protocols PDF

INTERNET PROTOCOLS  A protocol is a set of rules. Internet protocols are sets of rules governing communication within and between computers on a network. Protocol specifications define the format of the messages to be exchanged.  Timing is crucial to network operation. Protoc...

INTERNET PROTOCOLS  A protocol is a set of rules. Internet protocols are sets of rules governing communication within and between computers on a network. Protocol specifications define the format of the messages to be exchanged.  Timing is crucial to network operation. Protocols require messages to arrive within a certain amount of time so that computers do not wait indefinitely for messages that may have been lost. Therefore, systems maintain one or more times during transmission of data. Protocols also initiate alternative actions if the network does not meet the timing rules. Many protocols consist of a suite of other protocols that are stacked in layers. These layers depend on the operation of MAIN FUNCTIONS OF PROTOCOLS: Identifying errors Compressing the data Deciding how the data should be sent Addressing the data Deciding how to announce sent and received data Commonly Used Internet Protocol  COMMONLY USED PROTOCOLS: TCP/IP: the transmission control protocol /internet protocol (tcp/ip) suite of protocols has become the dominant standard for internetworking. TCP/IP represents a set of public standards that specify how packets of information are exchanged between computers over one or more networks.  COMMONLY USED PROTOCOLS: IPX/SPX: internetwork packet exchange/sequenced packet exchange is the protocol suite originally employed by novell corporation’s network operating system, netware. It delivers functions similar to those included in TCP/IP. Novell in its current releases supports the TCP/IP suite. A large installed base  COMMONLY USED PROTOCOLS: Netbeui: netbios extended user interface is a protocol used primarily on small windows NT networks. Netbeui cannot be routed or used by routers to talk to each other on a large network. Netbeui is suitable for small peer-to-peer networks, involving a few computers directly connected to each other. It can be used in conjunction with another routable protocol such as TCP/IP. This gives the network administrator  COMMONLY USED PROTOCOLS: APPLETALK: appletalk is a protocol suite used to network macintosh computers. It is composed of a comprehensive set of protocols that span the seven layers of the open systems interconnection (OSI) reference model. The appletalk protocol was designed to run over localtalk, which is the apple LAN physical  COMMONLY USED PROTOCOLS: HTTP: hypertext transfer protocol governs how files such as text, graphics, sound, and video are exchanged on the world wide web (www). The internet engineering task force (IETF) developed the standards for HTTP.  COMMONLY USED PROTOCOLS: HTTP: hypertext transfer protocol governs how files such as text, graphics, sound, and video are exchanged on the world wide web (www). The internet engineering task force (IETF) developed the standards for HTTP.  COMMONLY USED PROTOCOLS: FTP: file transfer protocol provides services for file transfer and manipulation. Ftp allows multiple simultaneous connections to remote file systems.  COMMONLY USED PROTOCOLS: SSH: Secure shell is used to securely connect to a remote computer.  COMMONLY USED PROTOCOLS: Telnet: it is an application used to connect to a remote computer that lacks security features.  COMMONLY USED PROTOCOLS: POP3: Post office protocol is used to download e-mail from a remote mail server.  COMMONLY USED PROTOCOLS: IMAP: internet message access protocol is also used to download E-mail from a remote mail server.  COMMONLY USED PROTOCOLS: SMTP: Simple mail transfer protocol is used to send e-mail to a remote e-mail server. IP Addressing  An IP Address is a number that is used to identify a device on the network. Each device on a network must have a unique IP Address to communicate with other network devices. Network devices are those that move data across the network, including hubs, switches, and routers. On a LAN, each host (device that sends or receives information on the network) and network device must have an IP Address within the same network to be able to communicate  A person’s name and fingerprints usually do not change. They provide a label or address for the person’s physical aspect—the body. A person’s mailing address, on the other hand, relates to where the person lives or picks up mail. This address can change. On a host, the media access control (MAC) address is assigned to the host network interface card (NIC) and is known as the physical address. The physical address remains the same regardless of where the host is  An IP address consists of a series of 32 binary bits (1s and 0s). It is very difficult for humans to read a binary IP address. For this reason, the 32 bits are grouped into four 8-bit bytes called octets. An IP address, even in this grouped format, is hard for humans to read, write, and remember. Therefore, each octet is presented as its decimal value, separated by a decimal point or period. This format is called dotted-decimal notation. When a host is  Imagine if you had to enter the 32-bit binary equivalent of this: 11000000101010000000000100000101. If you mistyped just 1 bit, the address would be different, and the host may not be able to communicate on the network. The logical 32-bit IP address is hierarchical and is composed of two parts. The first part identifies the network, and the second part identifies a host on that network. Both parts are required in an IP address.  For example, if a host has an IP address of 192.168.18.57, the first three octets, 192.168.18, identify the network portion of the address, and the last octet, 57, identifies the host. This is called hierarchical addressing, because the network portion indicates the network on which each unique host address is located. Routers only need to know how to reach each network, not the location of each individual host. FIVE CLASSES OF IP ADDRESS SUBNET MASK The subnet mask indicates the network portion of an IP address. Like the IP address, the subnet mask is a dotted- decimal number. Usually all hosts within a LAN use the same subnet mask.  255.0.0.0: class A, which indicates that the first octet of the IP address is the network portion  255.255.0.0: class B, which indicates that the first two octets of the IP address are the network portion  255.255.255.0: class C, which indicates that the first three octets of the IP address DEFAULT SUBNET MASKS FOR USABLE IP ADDRESSES Class D addresses are used for multicast groups. There is no need to allocate octet or bits to separate network and host addresses. Class E addresses are reserved for research use only.  IPCONFIG Ipconfig is a command used to find out the IP address of a certain network you are connected to.  HOW TO USE THE IPCONFIG COMMAND? 1) click on start button, then type cmd (command prompt) on the search box. 2) a black screen will appear as shown in the figure below. Command Prompt Window 3) Type ipconfig and press enter. The figure shows the IP configuration window using the ipconfig command. The information from this window will be useful because it shows the IP address, subnet mask and default IP Configuration in CMD Window  ASSIGNING A STATIC IP ADDRESS In a home network with several computers and devices, it is ideal to assign each of them a specific address. This is for the purpose of avoiding problems when you do troubleshooting which requires figuring out the IP address of each of them. It is also a means to prevent address conflicts between the devices. You can also PROCEDURES IN ASSIGNING AN IP ADDRESS ON A WINDOWS BASE COMPUTER SYSTEM: 1. Open the control panel’s network connections icon. 2. Open the icon representing your computer’s network connection. 3. Click the properties button in the status dialog box. 4. From the list of items, choose internet protocol Wireless Network Connections Properties Dialog Box 5. Click the properties button. The internet protocol (TCP/IP) properties dialog box appears. TCP / IPV4 Dialog Box 6. Type the IP address for your computer. Enter the appropriate IP address in the IP address section. 7. Type a subnet mask. The value used on a local network is commonly 255.255.255.0, but it can be different, such as 255.255.255.127. TCP / IPV4 Dialog Box 8. Type the default gateway address. The default gateway is the router, so type the router’s address. Assigning an IP Address 9. Type the address for the preferred DNS server. The address should be obtained from your internet service protocol. It is used to help your computer find web pages and other addresses on the internet. 10. Type the address for the alternate DNS server. The alternate domain name system (DNS) server’s IP address is something that your ISP provides.  ASSIGNING A DYNAMIC IP ADDRESS If more than a few computers comprise the LAN, manually configuring IP addresses for every host on the network can be time-consuming and prone to errors. In this case, using a dynamic host configuration protocol (DHCP) server would automatically assign IP addresses and greatly simplify the addressing process. Assigning a Dynamic IP Address Dynamic host configuration protocol (DHCP) is a software utility used to dynamically assign IP addresses to network devices. This dynamic process eliminates the need to manually assign IP addresses. A DHCP server can be set up and the hosts can be configured to automatically obtain an IP address. When a computer is set to obtain an IP address automatically, the other entire IP addressing configuration boxes are dimmed or disabled. The server maintains a list of IP addresses to assign, and it manages the process so that every device on the network receives a unique IP address. Each address is held for a predetermined amount of time. When the time expires, the DHCP server can use this address for any computer that joins the network. THESE ARE THE IP ADDRESS INFORMATION THAT A DHCP SERVER CAN ASSIGN TO HOSTS:  Ip address  subnet mask  default gateway  optional values, such as a domain name system (DNS) server address The DHCP server receives a request from a host. The server then selects IP address information from a set of predefined addresses that are stored in a database. After the IP address information is selected, the DHCP server offers these values to the requesting host on the network. If the host accepts the offer, the DHCP server leases the IP address for a specific period of time. Using a DHCP server simplifies the administration of a network because the software keeps track of IP addresses. Automatically configuring TCP/IP also reduces the possibility of assigning duplicate or invalid IP addresses. Before a computer on the network can take advantage of the DHCP server services, the computer must be able to identify the You can configure a computer to accept an IP address from a DHCP server by clicking the obtain an IP address automatically option in the NIC configuration window, If your computer cannot communicate with the DHCP server to obtain an IP address, the windows operating system automatically assigns a private IP address. If your computer is assigned an IP address in the range of 169.254.0.0 to 169.254.255.255, it can communicate with only other computers in the same range An example of when these private addresses would be useful is in a classroom lab where you want to prevent access outside to your network. This operating system feature is called automatic private IP addressing (APIPA). APIPA continually requests an IP address from a DHCP server for your computer.