minggu kelapan : internet infrastructure and internet protocol

Internet Infrastructure
The most important thing in it is network .Without network , we cannot send data to the internet . Every computer that connect to the internet is a part of network .

Internet Protocol : IP address
Every machine on the internet has it own Internet Protocol address . IP address is a language that computers use to communicate with the internet .For an example , IP address is like 216.27.22.162. It normally expessed in decimal number form . The four number for every of it was called octet . Octet act as to create classes that can be assigned to differentiate an address such as it was for goverment , organization and others . It was split into two thing , host and network .   The Network section always contains the first octet. It is used to identify the network that a computer belongs to. Host sometimes referred to as Node is identifies the actual computer on the network. The Host section always contains the last octet..


IP address can be classified into several classes such as ...

Class A

Class A addresses are assigned to networks with a very large number of hosts. The high-order bit in a class A address is always set to 0. The next seven bits (completing the first octet) complete the network ID. The remaining 24 bits (the last three octets) represent the host ID. This allows for 126 networks and 16,777,214 hosts per network.

 

Class B

Class B addresses are assigned to medium-sized to large-sized networks. The two high-order bits in a class B address are always set to binary 1 0. The next 14 bits (completing the first two octets) complete the network ID. The remaining 16 bits (last two octets) represent the host ID. This allows for 16,384 networks and 65,534 hosts per network.

 

Class C

Class C addresses are used for small networks. The three high-order bits in a class C address are set to binary 1 1 0. The next 21 bits (completing the first three octets) complete the network ID. The remaining 8 bits (last octet) represent the host ID. This allows for 2,097,152 networks and 254 hosts per network.

Class D
Class D addresses are reserved for IP multicast addresses. The four high-order bits in a class D address are always set to binary 1 1 1 0. The remaining bits are for the address that interested hosts recognize. Microsoft supports class D addresses for applications to multicast data to multicast-capable hosts on an internetwork.

Class E

Class E is an experimental address that is reserved for future use. The high-order bits in a class E address are set to 1111.

The network ID cannot begin with the number 127. The number 127 in a class A address is reserved for internal loopback functions. For example, 127.0.0.1 is the common loopback address.

·         Loopback means the interface created and designated to test a local port or interface. It routes test messages from their source device back to the source without any processing or modification.

·         The loopback IP address is the address used to access itself. A loopback interface is also known as a virtual IP, which does not associate with hardware interface.

·         The loopback address is used to test network software without physically installing a Network Interface Card (NIC), and without having to physically connect the machine to a TCP/IP network.

Domain Name System

Although people can type address information like http://207.241.148.80/ into their Web browser to visit sites, being able to use proper names like http://www.hotmail.com/ is much more practical. When someone types a site's name into their browser, DNS looks up the corresponding IP address for that site, the data required to make the desired network connections between Web browsers and Web servers.

The DNS organizes its servers into a hierarchy. For the Internet, so-called root name servers reside at the top of the DNS hierarchy. The Internet root name servers manage DNS server information for the Web's top-level domains (like ".com" and ".uk"). Servers at the next lower level of the DNS hierarchy track second-level domain names and addresses (like "hotmail.com").

Hierarchy of domain names

ISP

Short for Internet Service Provider, it refers to a computer access to the Internet. The service provider usually provides a software package,username and password. You can then log on to the Internet and browse the World Wide Web and send and receive e-mail. ISPs also serve large companies, providing a direct connection from the company's networks to the Internet. ISPs.

An ISP is a company that provides individuals and other companies access to the Internet and other related services such as Web site building and virtual hosting. An ISP has the equipment and the telecommunication line access required to have a point-of-presence on the Internet for the geographic area served. The larger ISPs have their own high-speed leased lines so that they are less dependent on the telecommunication providers and can provide better service to their customers.

HTTP  (Hypertext Transfer Protocol)

HTTP stands for Hypertext Transfer Protocol. It is an TCP/IP based communication protocol which is used to deliver virtually all files and other data, collectively called resources, on the World Wide Web. These resources could be HTML files, image files, query results, or anything else.Every Web server on the Internet conforms to the hypertext transfer protocol (HTTP). The Hypertext Transfer Protocol (HTTP) is an application-level TCP/IP based protocol with the lightness and speed necessary for distributed, collaborative, hypermedia information systems (internet).

There are three important things about HTTP of which you should be aware:

·         HTTP is connectionless: After a request is made, the client disconnects from the server and waits for a response. The server must re-establish the connection after it process the request.

·         HTTP is media independent: Any type of data can be sent by HTTP as long as both the client and server know how to handle the data content. How content is handled is determined by the MIME specification.

·         HTTP is stateless: This is a direct result of HTTP's being connectionless. The server and client are aware of each other only during a request. Afterwards, each forgets the other. For this reason neither the client nor the browser can retain information between different request across the web pages.

The diagram shows where HTTP Protocol fits in communication:

minggu ketujuh : unbounded media

what is unbounded media ?

• No physical connection is required.

• Space or air is the transmission medium for electromagnetic waves.

• Source and destination can be static or mobile.

• Broad spectrum from low to high bandwidth is available.

• Can be quickly implemented.

   

  Terrestial Microwave

  - require line-of-sight transmission and reception microwave
  - the taller the antennas, the longer the sight distance
  - signals are propagate in one direction in a time
  - consist of repeater which function to increase the distance
•  

They are two type of antenna 
a) Parabolic Dish
- catching a wide range of waves and directing to a focus
  -higher frequencies for higher data rates
  -10-60 GHz

b) Horn
  -looks like a gigantic scoop
  -deflected the waves outward in a series of narrow parallel beams
  -received transmission are collected by the scooped shape


Satellite microwave
The main problem with aero wave communication is the curvature of the earth, mountains & other structure often block the line of side. Due to this reason, many repeats are required for long distance which increases the cost of data transmission between the two points. This problem is recommended by using satellites.

Satellite micro wave transmission is used to transmit signals through out the world. These system use satellites in orbit about 50,000 Km above the earth. Satellite dishes are used to send the signals to the satellite where it is again send back down to the receiver satellite. These transmissions also use directional parabolic antenna’ with in line of side.

In satellite communication micro wave signals at 6 GHz is transmitted from a transmitter on the earth through the satellite position in space. By the time signal reaches the satellites becomes weaker due to 50,000 Km distance. The satellite amplifies week signals and transmits it back to the earth at the frequency less than 6 GHz.


The difference between 3g and 4g

3G is currently the world’s best connection method when it comes to mobile phones, and especially mobile Internet. 3G stands for 3rd generation as it  is just that in terms of the evolutionary path of the mobile phone industry. 4G means 4th generation. This is a set of standard that is being developed as a future successor of 3G in the very near future.

The biggest difference between the two is in the existence of compliant technologies. There are a bunch of technologies that fall under 3G, including WCDMA, EV-DO, and HSPA among others. Although a lot of mobile phone companies are quick to dub their technologies as 4G, such as LTE, WiMax, and UMB, none of these are actually compliant to the specifications set forth by the 4G standard. These technologies are often referred to as Pre-4G or 3.9G.

4G speeds are meant to exceed that of 3G. Current 3G speeds are topped out at 14Mbps downlink and 5.8Mbps uplink. To be able to qualify as a 4G technology, speeds of up to 100Mbps must be reached for a moving user and 1Gbps for a stationary user. So far, these speeds are only reachable with wired LANs.

Another key change in 4G is the abandonment of circuit switching. 3G technologies use a hybrid of circuit switching and packet switching. Circuit switching is a very old technology that has been used in telephone systems for a very long time. The downside to this technology is that it ties up the resource for as long as the connection is kept up. Packet switching is a technology that is very prevalent in computer networks but has since appeared in mobile phones as well. With packet switching, resources are only used when there is information to be sent across. The efficiency of packet switching allows the mobile phone company to squeeze more conversations into the same bandwidth. 4G technologies would no longer utilize circuit switching even for voice calls and video calls. All information that is passed around would be packet switched to enhance efficiency.

 so we can conclude that -

1. 3G technologies are in widespread use while 4G compliant technologies are still in the horizon

2. 4G speeds are much faster compared to 3G

3. 3G is a mix of circuit and packet switching network while 4G is only a packet switching network

minggu keenam : cabling

Cable is the medium through which information usually moves from one network device to another. There are several types of cable which are commonly used with LANs. In some cases, a network will utilize only one type of cable, other networks will use a variety of cable types. The type of cable chosen for a network is related to the network's topology, protocol, and size. Understanding the characteristics of different types of cable and how they relate to other aspects of a network is necessary for the development of a successful network.

The following sections discuss the types of cables used in networks.

• Unshielded Twisted Pair (UTP) Cable
• Shielded Twisted Pair (STP) Cable
• Coaxial Cable
• Fiber Optic Cable

Unshielded twisted pair (UTP) is the most popular and is generally the best option for school networks

Unshielded twisted pair

The quality of UTP may vary from telephone-grade wire to extremely high-speed cable. The cable has four pairs of wires inside the jacket. Each pair is twisted with a different number of twists per inch to help eliminate interference from adjacent pairs and other electrical devices. The tighter the twisting, the higher the supported transmission rate and the greater the cost per foot. 

Categories of Unshielded Twisted Pair

Category	Speed	Use
1	1 Mbps	Voice Only (Telephone Wire)
2	4 Mbps	LocalTalk & Telephone (Rarely used)
3	16 Mbps	10BaseT Ethernet
4	20 Mbps	Token Ring (Rarely used)
5	100 Mbps (2 pair)	100BaseT Ethernet
	1000 Mbps (4 pair)	Gigabit Ethernet
5e	1,000 Mbps	Gigabit Ethernet
6	10,000 Mbps	Gigabit Ethernet

Unshielded Twisted Pair Connector

The standard connector for unshielded twisted pair cabling is an RJ-45 connector. This is a plastic connector that looks like a large telephone-style connector. A slot allows the RJ-45 to be inserted only one way. RJ stands for Registered Jack, implying that the connector follows a standard borrowed from the telephone industry. This standard designates which wire goes with each pin inside the connector.

RJ-45 connector

Shielded Twisted Pair (STP) Cable

Although UTP cable is the least expensive cable, it may be susceptible to radio and electrical frequency interference. If you must place cable in environments with lots of potential interference, or if you must place cable in extremely sensitive environments that may be susceptible to the electrical current in the UTP, shielded twisted pair may be the solution. Shielded cables can also help to extend the maximum distance of the cables.

Shielded twisted pair cable is available in three different configurations:

1. Each pair of wires is individually shielded with foil.
2. There is a foil or braid shield inside the jacket covering all wires.
3. There is a shield around each individual pair, as well as around the entire group of wires.

Coaxial Cable

Coaxial cabling has a single copper conductor at its center. A plastic layer provides insulation between the center conductor and a braided metal shield. The metal shield helps to block any outside interference from fluorescent lights, motors, and other computers.

Coaxial cable

Although coaxial cabling is difficult to install, it is highly resistant to signal interference. In addition, it can support greater cable lengths between network devices than twisted pair cable. The two types of coaxial cabling are thick coaxial and thin coaxial.

Thin coaxial cable is also referred to as thinnet. 10Base2 refers to the specifications for thin coaxial cable carrying Ethernet signals. The 2 refers to the approximate maximum segment length being 200 meters. In actual fact the maximum segment length is 185 meters. Thin coaxial cable has been popular in school networks, especially linear bus networks.

Thick coaxial cable is also referred to as thicknet. 10Base5 refers to the specifications for thick coaxial cable carrying Ethernet signals. The 5 refers to the maximum segment length being 500 meters. Thick coaxial cable has an extra protective plastic cover that helps keep moisture away from the center conductor. This makes thick coaxial a great choice when running longer lengths in a linear bus network. One disadvantage of thick coaxial is that it does not bend easily and is difficult to install.

Coaxial Cable Connectors

The most common type of connector used with coaxial cables is the Bayone-Neill-Concelman (BNC) connector. Different types of adapters are available for BNC connectors, including a T-connector, barrel connector, and terminator. Connectors on the cable are the weakest points in any network. To help avoid problems with your network, always use the BNC connectors that crimp, rather screw, onto the cable.

Fig. 4. BNC connector

Fiber Optic Cable

Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials. It transmits light rather than electronic signals eliminating the problem of electrical interference. This makes it ideal for certain environments that contain a large amount of electrical interference. It has also made it the standard for connecting networks between buildings, due to its immunity to the effects of moisture and lighting.

Fiber optic cable has the ability to transmit signals over much longer distances than coaxial and twisted pair. It also has the capability to carry information at vastly greater speeds. This capacity broadens communication possibilities to include services such as video conferencing and interactive services. The cost of fiber optic cabling is comparable to copper cabling; however, it is more difficult to install and modify. 10BaseF refers to the specifications for fiber optic cable carrying Ethernet signals.

The center core of fiber cables is made from glass or plastic fibers. A plastic coating then cushions the fiber center, and kevlar fibers help to strengthen the cables and prevent breakage. The outer insulating jacket made of teflon or PVC.

Fiber optic cable

There are two common types of fiber cables -- single mode and multimode. Multimode cable has a larger diameter; however, both cables provide high bandwidth at high speeds. Single mode can provide more distance, but it is more expensive.

Specification	Cable Type
10BaseT	Unshielded Twisted Pair
10Base2	Thin Coaxial
10Base5	Thick Coaxial
100BaseT	Unshielded Twisted Pair
100BaseFX	Fiber Optic
100BaseBX	Single mode Fiber
100BaseSX	Multimode Fiber
1000BaseT	Unshielded Twisted Pair
1000BaseFX	Fiber Optic
1000BaseBX	Single mode Fiber
1000BaseSX	Multimode Fiber

minggu kelima : network topology

Network topology is the layout pattern of interconnections of the various elements (links, nodes, etc.) of a computer or biological network.Network topologies may be physical or logical.

There are several basic types of topology in networks:

(1) BUS TOPOLOGY

A linear bus topology consists of a main run of cable with a terminator at each end. All nodes (file server, workstations, and peripherals) are connected to the linear cable.Ethernet and LocalTalk networks use a linear bus topology.The bus cable carries the transmitted message along the cable. As the message arrives at each workstation, the workstation computer checks the destination address contained in the message to see if it matches it's own. If the address does not match, the workstation does nothing more. If the workstation address matches that contained in the message, the workstation processes the message. The message is transmitted along the cable and is visible to all computers connected to that cable.

Advantages of a Linear Bus Topology

• Easy to connect a computer or peripheral to a linear bus.
• Requires less cable length than a star topology.

Disadvantages

• Entire network shuts down if there is a break in the main cable.
• A faulty cable or workstation will take the entire LAN down
• terminators are required at both ends of the backbone cable.
• Difficult to identify the problem if the entire network shuts down.
• Not meant to be used as a stand-alone solution in a large building.

(2) STAR TOPOLOGY

A star topology is designed with each node (file server, workstations, and peripherals) connected directly to a central network hub or concentrator. Data on a star network passes through the hub or concentrator before continuing to its destination. The hub or concentrator manages and controls all functions of the network. It also acts as a repeater for the data flow.This configuration is common with twisted pair cable; however, it can also be used with coaxial cable or fiber optic cable.The protocols used with star configurations are usually Ethernet or LocalTalk.

Advantages

• Easy to install, and wire.
• Easy to add new workstations
• No disruptions to the network when connecting or removing devices.
• Any non-centralised failure will have very little effect on the network
• Easy to detect faults and to remove parts.
• Centralized control Centralized network/hub monitoring

Disadvantages

• Requires more cable length than a linear topology.
• If the hub or concentrator fails, nodes attached are disabled.
• More expensive than linear bus topologies because of the cost of the concentrators.

(3) STAR-WIRED

A star-wired topology may appear (externally) to be the same as a star topology. Internally, the MAU (multistation access unit) of a star-wired ring contains wiring that allows information to pass from one device to another in a circle or ring. The Token Ring protocol uses a star-wired topology.

(4) TREE TOPOLOGY

A tree topology combines characteristics of linear bus and star topologies.It consists of groups of star-configured workstations connected to a linear bus backbone cable. Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.

Advantage

• Point-to-point wiring for individual segments.

Disadvantages

• Overall length of each segment is limited by the type of cabling used.
• if the backbone line breaks, the entire segment goes down.
• More difficult to configure and wire than other topologies.

(5) ETHERNET

      Ethernet is the most widely-installed local area network ( LAN) technology. Specified in a standard, IEEE 802.3, Ethernet was originally developed by Xerox from an earlier specification called Alohanet (for the Palo Alto Research Center Aloha network) and then developed further by Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Ethernet is also used in wireless

ethernet cables

(6) LOCALTALK

     

    LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer. LocalTalk specifies a system of shielded twisted pair cabling, plugged into self-terminating transceivers, running at a rate of 230.4 kbit/s.CSMA/CA was implemented as a random multiple access method.

minggu 4:networking

what is computer networking ??
-connecting a computer with other computer or other devices to enable them to communicate with each other .
It can be :
 -Computer devices/equipment
–transmission media to send/control data/signals,
–Communication devices to transmit/send data from sources to destinations
–softwares


There are several types of this LAN based geographic :
1.LAN-local area network
2.MAN-Metropolitan area network
3.WAN-Wide area network


And then we go to network component .We can categorise it into 5 component . 


1.Terminals
-Refers to data sources and destination .
examples-workstation,personal computer,terminals,automatic teller machine


2.Transmission Media
-used to transmit data in a networked enviroment
-transmit pulse through a medium
-there are 2 types of it, bounded and unbounded


Bounded-twisted pair wire,co-axial cable,fiber optic cable
Unbounded-AM and FM radio,TV broadcasting,Microwave signal


3.Network Electronic Devices
-Devices that control data transmission from sources to destination
-Also act as interface between different transmission media


Examples-Bridges,Hub,Routers,Multiplexers,Gateway,Private Branch


4.Network
-a network operating system (NOS)
-control data transmission,a network & it message,traffic and queues .
-provide certain administrative function,including security


5.Network Architecture Standards
-Standard to enable devices made by different companies to work/communicate with each other 
-Blueprint of standard for a network consisting of item such as choices of media,media interface,encoding method and transmission protocol.
-Needed to ensure interoperability between various devices and equipment made by different vendors .