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This paper explains the different networking hardware components by comparing and contrasting with other devices and also explains about the protocols that represented in the different layers of the OSI model, and explaining how protocols can be optimized for better performances. This paper also tries to explain the responsibilities of a network administrator.
The paper is divided into parts to explain the different topics. Part one discusses the different network devices. Compares and contrasts with other network devices. Part two explains the different protocols that used in the representative OSI layers, Part three is based on the OSI layers and trying to develop a method to improve the performance of the network device. The last part of the assignment explains the level and type of job that a person with the skill sets explained in the paper can have.
Transmission medium is the medium through which different devices on a network are connected. It acts at the layer one of the network model. There are different types of network transmission medium, and can be categorized broadly into three.
- COPPER CABLE
- FIBER OPTIC CABLE
There are three types of copper cable are available, unshielded twisted-pair (UTP), shielded twisted-pair (STP), and coaxial cable. Copper cables are cheaper and easy to maintain. Copper cable has its own disadvantages as well. The spectrum is limited in case of copper cables. It's mainly used for point o point connectivity for devices which are not separated by a great distance. The main reason being the resistance in the copper cables. Resistance can decrease the efficiency of the data transmission considerably.FIBER OPTIC CABLE
Fiber optic cables are used for connections which require high bandwidth, like in the case of backbone connections. Since the fiber optic technology uses light as a medium, there won't be resistance playing part in decrease in data transmission. There won't be interference from different medium in case of fiber optic. It gives much better security compared to other transmission medium since tapping data transmission is almost impossible. It's an expensive medium compared to other transmission medium, and is expensive to maintain as well since the equipments used in this are also expensive.
Advantages of Fibre optic cables
- There will be near zero interference from other medium
- Light is used to transmit data.
- Light can encode more information that electrical signals, so they carry more information than a wire
- Light can carry a signal over a single fibre
- Expensive compared to other medium of transfer
The different types of wireless media are microwave, radio frequencies, satellite and infrared. Wireless medium is used in places where mobility is required. One advantage of wireless networks is that it can be incorporated to other networks with minimum alteration to the structure of the network.
- Compared to other medium it will be very cheaper
- Very easy to implement
- Wireless medium support very less data rates
- There is no constant reliability in wireless medium
A hub is a multi port device which works in the physical layer of OSI (Open System Interconnection). The role of hub is, when a packets arrives in a particular port the Hub will broadcast the packets to all other ports on the hub. So all connected pc can see what all the information are going through the hub. The hub is an unsophisticated network device. The hub is also called Multi port repeaters because both have the same characteristics. It performs as a single broadcast domain as well as single collision domain. This is called because of when attempting to connect two or more computers at the same time and this will cause the signals to crash. Hub does the half duplex communication. The hardware part of the hub have a PCB(printed circuit board), and RJ45 port. The hub has no software part, the hardware itself used to regenerate the signals send and received to all other active ports.SWITCH
Switches are the layer two devices having almost the same function of a hub in the network. The switch maintains a Mac address of the connected hosts. The switch first gives a broadcast to update all the Mac addresses in its list and then it unicast to the host using the destination Mac address. The two types of switches, manageable and non manageable. The manageable ones can be configured for its each port and has got access lists for security implementation. While the non manageable ones cannot be configured manually. The switches uses two methods for forwarding the frame one is store and forward (store the frame check for CRC and then forward) and the other is cut through (no error check). Switches have single broadcast domain but have multiple collision domains.ROUTER
It is a device used for routing and forwarding information between two network devices connected in a network. The router either connects two IP networks or an IP network to an internet service provider. It is described to play its role in network layer. The router consists of two interfaces which supports the IP protocol. The IP header or the network layer header helps the router to forward the received information or packets to the destination. It also helps the router to decide the interface which has to be used and the method to be implemented. The Minimum Transfer Unit (MTU) of an interface is checked before a packed is forwarded. If a packet is larger than the MTU, it is subdivided into smaller packets. A packet is discarded if it is attached with a don't fragment bit in the packed header and it is reported as an ICMP error informing about its interface MTU size. The router has all its information in a routing table. The only difference between the routing table and filter table is that, it consists of IP addresses instead of MAC addresses. They look similar in link layer bridges and switches. The IP address of the router can be configured either statically or dynamically based on the protocol used in the router. The contents of the routing table are updated periodically by the routing protocol which will help the router to have the updated information of the routing table and choose the best path to reach the destination. Manual configuration of routers can be done using console port and command line interface. The hardware part of a router consists of processor, NVRAM, Flash, ROM, Console and interface ports. IOS is the software used in the routers. It is Internet work operating systems. Different versions are also available depending on the router.HOSTS
Hosts are the end devices in a network. In a client server model it's the hosts which give the information to be processed by the server. Hosts can be of any type. It can be a computer or a PDA or a mobile device which is connected to the network.. Hosts of a network are distinguished by the ip address given to it. Nodes are connected to a network through different types of media depending upon the type of network it is connected to it. In case of a mobile device it's connected to the network through a wireless medium. Whereas simple computers acting as nodes can be connected using copper cables. The servers serve for the requests from the node. Nodes makes data input more easier and having the servers make the processing to be done at one place rather than over different computers, which saves time and money as well as backing up data is easier. .DATA LINK LAYER
Data link layer is layer two in the OSI model. This layer has the responsibilities to move the frames for physical layer the data link layer create frame with a header and trailer frame and send to the physical layer. . Data link layers consist two sub layer that are Media Access Control(MAC), and Logical Link Control(LLC). MAC methods are the shared media and point to point connections. In shared media it has controlled for each nodes have its own time to use medium like ring topology, and in contention based all the nodes contend for the use of medium as bus topology. The MAC point to point connection refers, in half duplex mode the pc can send or receive at one time when long distance and low bandwidth, in half duplex mode the pc can send and receive the data at the same time. The LLC sub layer is use to transmit the multiplex protocol over the MAC layer. The protocol is using in the Data link are RIP, IGRP, EIGRP, OSPF, PPP, Ethernet etc. Ethernet protocol is used for local area network (multi-node), Point-To- Point,HDLC,ADCCP are using for dual node connections.NETWORK LAYER
Network layer is consist layer two in OSI model. The network layer encapsulates the packet into frame and send to the data link layer. This layer performs an important role between transport and data link layers. Network layer includes logical addressing and it converts logical address into physical address and send to the data link layer. The Network layer protocols are IP (Internet Protocol). It is a connectionless protocol and there is no reliability whether the data reach the destination. The IP protocols versions are IPv4 and IPv6, IPv4 has 32bit decimal address whereas IPv6 has 48bit hexadecimal value. ICMP (Internet Control Message Protocol) is one of the major protocols that used in Internet Protocol. This protocol is used to send the error message like instance, or the host is not responding to the other clients. ARP (Address Resolution Protocol) is another protocol is used to find out the hardware address using the network layer address. Another network layer protocol is RARP (Reverse Address Resolution Protocol).TRANSPORT LAYER
Transport layer is layer three in OSI model. The transport layers responsibilities are segmenting the data and add header to the application data, using this header information transport layer reassemble the segment into application data. The transport layer occurs between session layer and network layer. The transport layer protocols are TCP (Transmission Control Protocol), UDP (User Datagram Protocol) and SCTP (Stream Control Transmission Protocol).TCP is the connection-oriented protocol whereas UDP is the connection-less protocol. TCP header provides source and destination address, sequence number to provide the same order delivery and acknowledgement for the receiving segments. The UDP header provides only source and designation address. The TCP protocol applications are web browsing, e-mail, file transfers. UDP applications are video-streaming, voice over IP, these are unreliable. UDP does not provide the acknowledgment for receiving the datagram. It sometimes called Universal Datagram Protocol or Unreliable Datagram Protocol. The packet header size of the UDP is 8 bytes whereas the TCP is 20-60 bytes.PART IV.
The protocol which I have chosen to improve the performance of is TCP (Transmission control Protocol). TCP is the protocol which is using the Transport layer of the OSI model. This protocol is connection-oriented, it sends the acknowledgement to the source when the data receive. TCP provides a communication medium between processes on each system. This medium is reliable, streaming and full-duplex. To accomplish this performance the TCP protocol divide the session stream data into separate segments and attach a TCP header into each header. An IP packet added to this header, this header is send to the network to delivery.
The TCP protocol is considered as a three-way handshake protocol. After establishing the TCP session, TCP protocol needs to improve the performance. One of the methods is use a good protocol stack. This helps to get better performance to the protocol. Another method is implement larger buffers with TCP window-Scaling options. The TCP flow algorithm try to work at the data rate at the low bandwidth and delay transmit the data to end to end network device. Using high bandwidth and delay the sender and receiver assist more efficiently.
Implement a TCP selective acknowledgement (SACK) mechanism: SACK is a method which is combined with a selective repeat transmission policy is used to help conquer the limitations of old TCP experiences when a sender can learn only about a single lost packet per RRT.
Title & Level of the Jobs:
The title of the job will be Network Administrator and the level of the jobs are creating a suitable network infrastructure for which company is working and make decision about which protocol is used to be implement the router and switches, configure the access lists and firewalls for restrict the unauthorized usage.Responsibilities:
Manage the whole network that undertaken, check all the networks are running properly and troubleshoot when error occur. Update the network topology when need to add the host in that network.Day to day task that would be undertaken
Daily check whether any complaints registered, if it is take necessary action to solve the problem and also check all the devices are running faultlessly. Take the backup if any update made.What would be expected from your manager
- Technical guidance and moral support.
- Management and well understanding
Who would be the contacts:
Manager, teachers, friends from networking field, company AMC (Annual Maintenance Contract) and customer care number of the device which used.