Network Repeater And Router Computer Science Essay

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10BASE-2, one of several physical media specified by IEEE 802.3 for use in an Ethernet local area network, consists of Thinwire coaxial cable with a maximum segment length of 185 meters. Like other specified media, 10BASE-2 supports Ethernets 10 Mbps data rate.

This designation is an Institute of Electrical and Electronics Engineers (IEEE) shorthand identifier. The "10" in the media type designation refers to the transmission speed of 10 Mbps. The "BASE" refers to base-band signalling, which means that only Ethernet signals are carried on the medium (or, with 10BASE-36, on a single channel). The "T" represents twisted-pair; the "F" represents fiber optic cable; and the "2", "5", and "36" refer to the coaxial cable segment length (the 185 meter length has been rounded up to "2" for 200).

10Base5

10BASE5 (also known as thick Ethernet or thicknet) is the original "full spec" variant of Ethernet cable, using cable similar to RG-8/U coaxial cable but with extra braided sheiding. This is a stiff, 0.375-inch (9.5 mm) diameter cable with an impedance of 50 ohms (Ω), a solid centre conductor, a foam insulating filler, a shielding braid, and an outer jacket. The outer sheath is often yellow-to-orange/brown foam fluorinated ethylene propylene (for fire resistance) so it often is called "yellow cable", "orange hose", or sometimes humorously "frozen yellow garden hose".

10BASE5 has been superseded due to the immense demand for high speed networking, the low cost of Category 5 Ethernet cable, and the popularity of802.11 wireless networks. Both 10BASE2 and 10BASE5 have become obsolete.

10BaseT

Ethernet over twisted pair refers to the use of cables that contain insulated copper wires twisted together in pairs for the physical layer of an Ethernet network-that is, a network in which the Ethernet protocol provides the data link layer. Other Ethernet cable standards use coaxial cable or optical fiber. There are several different standards for this copper-based physical medium. The most widely used are 10BASE-T, 100BASE-TX, and 1000BASE-T, running at 10 Mbps (also Mbps or Mbs-1), 100 Mbps, and 1000 Mbps (1 Gbps), respectively. These three standards all use the same connectors. Higher speed implementations nearly always support the lower speeds as well, so that in most cases different generations of equipment can be freely mixed. They use 8 position modular connectors, usually called RJ45 in the context of Ethernet over twisted pair. The cables usually used are four-pair twisted pair cable (though 10BASE-T and 100BASE-TX only actually require two of the pairs). Each of the three standards support both full-duplex and half-duplex communication.

The common names for the standards derive from aspects of the physical media. The number refers to the theoretical maximum transmission speed in megabits per second (Mbps). The BASE is short for baseband, meaning that there is no frequency-division multiplexing (FDM) or other frequency shifting modulation in use; each signal has full control of wire, on a single frequency. The T designates twisted pair cable, where the pair of wires for each signal is twisted together to reduce radio frequency interference and crosstalk between pairs (FEXT and NEXT). Where there are several standards for the same transmission speed, they are distinguished by a letter or digit following the T, such as TX.

Advantages and Disadvantages

10Base2-An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signalling, with a contiguous cable segment length of 100 meters and a maximum of 2 segments 

10Base5-An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signalling, with 5 continuous segments not exceeding 100 meters per segment. 

10BaseT-An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signalling and twisted pair cabling.

Task 1: part b

Network Repeater

A repeater connects two segments of your network cable. It retimes and regenerates the signals to proper amplitudes and sends them to the other segments. When talking about, ethernet topology, you are probably talking about using a hub as a repeater. Repeaters require a small amount of time to regenerate the signal. This can cause a propagation delay which can affect network communication when there are several repeaters in a row. Many network architectures limit the number of repeaters that can be used in a row. Repeaters work only at the physical layer of the OSI network model.

Bridge

A bridge reads the outermost section of data on the data packet, to tell where the message is going. It reduces the traffic on other network segments, since it does not send all packets. Bridges can be programmed to reject packets from particular networks. Bridging occurs at the data link layer of the OSI model, which means the bridge cannot read IP addresses, but only the outermost hardware address of the packet. In our case the bridge can read the ethernet data which gives the hardware address of the destination address, not the IP address. Bridges forward all broadcast messages. Only a special bridge called a translation bridge will allow two networks of different architectures to be connected. Bridges do not normally allow connection of networks with different architectures. The hardware address is also called the MAC (media access control) address. To determine the network segment a MAC address belongs to, bridges use one of:

Transparent Bridging - They build a table of addresses (bridging table) as they receive packets. If the address is not in the bridging table, the packet is forwarded to all segments other than the one it came from. This type of bridge is used on ethernet networks.

Source route bridging - The source computer provides path information inside the packet. This is used on Token Ring networks.

Network Router

A router is used to route data packets between two networks. It reads the information in each packet to tell where it is going. If it is destined for an immediate network it has access to, it will strip the outer packet, readdress the packet to the proper ethernet address, and transmit it on that network. If it is destined for another network and must be sent to another router, it will re-package the outer packet to be received by the next router and send it to the next router. The section on routing explains the theory behind this and how routing tables are used to help determine packet destinations. Routing occurs at the network layer of the OSI model. They can connect networks with different architectures such as Token Ring and Ethernet. Although they can transform information at the data link level, routers cannot transform information from one data format such as TCP/IP to another such as IPX/SPX. Routers do not send broadcast packets or corrupted packets. If the routing table does not indicate the proper address of a packet, the packet is discarded.

Brouter

There is a device called a brouter which will function similar to a bridge for network transport protocols that are not routable, and will function as a router for routable protocols. It functions at the network and data link layers of the OSI network model.

Gateway

A gateway can translate information between different network data formats or network architectures. It can translate TCP/IP to AppleTalk so computers supporting TCP/IP can communicate with Apple brand computers. Most gateways operate at the application layer, but can operate at the network or session layer of the OSI model. Gateways will start at the lower level and strip information until it gets to the required level and repackage the information and work its way back toward the hardware layer of the OSI model. To confuse issues, when talking about a router that is used to interface to another network, the word gateway is often used. This does not mean the routing machine is a gateway as defined here, although it could be.

Task 1: Part C

An Internet Protocol address (IP address) is a numerical annuls that is assigned to any device participating in a computer network that uses the Internet Protocol for communication between its nodes. In other words, it is an address that is assigned to any device that is connected to a network that follows the Internet Protocol, i.e. the Internet. An IP address serves two principal functions; host or network interface identification and location addressing. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."

The designers of TCP/IP defined an IP address as a 32-bit number[1] and this system, known as Internet Protocol Version 4 (IPv4), is still in use today. However, due to the enormous growth of the Internet and the predicted depletion of available addresses, a new addressing system (IPv6), using 128 bits for the address, was developed in 1995, standardized by RFC 2460 in 1998, and is in world-wide production deployment.

Although IP addresses are stored as binary numbers, they are usually displayed in human-readable notations, such as 208.77.188.166 (for IPv4), and 2001:db8:0:1234:0:567:1:1 (for IPv6).

The Internet Protocol is used to route data packets between networks; IP addresses specify the locations of the source and destination nodes in the topology of the routing system. For this purpose, some of the bits in an IP address are used to designate a subnetwork. The number of these bits is indicated in CIDR notation, appended to the IP address; e.g., 208.77.188.166/24.

As the development of private networks raised the threat of IPv4 address exhaustion, RFC 1918 set aside a group of private address spaces that may be used by anyone on private networks. Such networks require network address translator gateways to connect to the global Internet.

The Internet Assigned Numbers Authority (IANA) manages the IP address space allocations globally and cooperates with five regional Internet registries (RIRs) to allocate IP address blocks to local Internet registries (Internet service providers) and other entities

Task 2: Part A

Bandwidth

In computer networking and computer science, bandwidth, network bandwidth, data bandwidth or digital bandwidth is a bit rate measure of available or consumed data communication resources expressed in bits/second or multiples of it (kilobits/s, megabits/s etc.).

Note that in textbooks on data transmission, digital communications, wireless communications, electronics, etc., bandwidth refers to analogue signal bandwidth measured in hertz - the original meaning of the term. Some computer networking authors prefer less ambiguous terms such as bit rate, channel capacity and throughput rather than bandwidth in bit/s, to avoid this confusion.

Basic Factors

Cultural Identity

Racial Identity

Ethnic Identity

Gender Role Identity

Individual Personality

Social Class Identity

Age Identity

Roles Identity

Task 2: Part C

Physical Address

In computing, a physical address, also real address, or binary address, is the memory address that is electronically (in the form of binary number) presented on the computer address bus circuitry in order to enable the data bus to access a particular storage cell of main memory.

In a computer with virtual memory, the term physical address is used mostly to differentiate from a virtual address. In particular, in computers utilizing memory management unit (MMU) to translate memory addresses, the virtual and physical addresses refer to an address before and after MMU translation respectively.

Difference between Physical address and Logical address

In a system, there are two types of addresses: logical and physical. Another name for logical address is IP address and it is set by your Internet service provider (ISP) or your router. If you have a router then you have a LAN, which sets a logical address for your computer. Your router will have an logical address set by your ISP. 

The physical address is also called the MAC address and it is generated by the manufacturer. (but only to a given extent) 

Because a MAC address is assigned (by the FCC) to a company to use for a range of products. 

For example: 

01:23:45:00:00:00 - 01:23:45:FF:FF:FF 

Would be their "range" of MAC addresses. They use a coding called Hex which is not to far off from what you know which is base-10 (0-9). 

Instead hex uses (0-F). 0123456789ABCDEF 

A = 10, B = 11, etc.

Task 2: Part C

"The difference between Layer 2 and Layer 3 switching is the type of information inside the frame that is used to determine the correct output interface. With Layer 2 switching, frames are switched based on MAC address information. With Layer 3 switching, frames are switched based on network-layer information."

Task 3:

OSI Model

The Open Systems Interconnection model (OSI model) is a product of the Open Systems Interconnection effort at the International Organization for Standardisation. It is a way of sub-dividing a communications system into smaller parts called layers. A layer is a collection of conceptually similar functions that provide services to the layer above it and receives services from the layer below it. On each layer an instance provides services to the instances at the layer above and requests service from the layer below.

For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of the path. Conceptually two instances at one layer are connected by a horizontal protocol connection on that layer.

Encryption and Decryption

Encryption and decryption are both methods used to ensure the secure passing of messages and other sensitive documents and information.

Encryption basically means to convert the message into code or scrambled form, so that anybody who does not have the 'key' to unscramble the code cannot view it. This is usually done by using a 'cipher'. A cipher is a type of algorithm used in encryption that uses a certain described method to scramble the data. The cipher can only be 'deciphered' with a 'key'. A key is the actual 'described method' that was used to scramble the data, and hence the key can also unscramble the data.

When the data is unscrambled by the use of a key, that is what is known as 'decryption'. It is the opposite of encryption and the 'described method' of scrambling is basically applied in reverse, so as to unscramble it. Hence, the jumbled and unreadable text becomes readable once again.

In network security, password encryption as well as document encryption is a major player. Without it, there would be no 'security' in the network. Also, encryption is used for all sorts of files and all forms of digital transfers as well. It is used on the internet to safeguard websites and copyrighted material, as well as in bank ATM machines. The encryption process plays a major factor in our technology advanced lives.

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