WAN

wide area network (WAN)

wide area network (WAN) is a telecommunication network that covers a broad area (i.e., any network that links across metropolitan, regional, or national boundaries). Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations. In essence this mode of telecommunication allows a business to effectively carry out its daily function regardless of location.

This is in contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively.


Design options

The textbook definition of a WAN is a computer network spanning regions, countries, or even the world. However, in terms of the application of computer networking protocols and concepts, it may be best to view WANs as computer networking technologies used to transmit data over long distances, and between different LANs, WANs and other localised computer networking architectures. This distinction stems from the fact that common LAN technologies operating at Layer 1/2 (such as the forms of Ethernet or Wifi) are often geared towards physically localised networks, and thus cannot transmit data over tens, hundreds or even thousands of miles or kilometres.

WANs necessarily do not just connect physically disparate LANs. A CAN, for example, may have a localised backbone of a WAN technology, which connects different LANs within a campus. This could be to facilitate higher bandwidth applications, or provide better functionality for users in the CAN.

WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.

Academic research into wide area networks can be broken down into three areas: mathematical models, network emulation and network simulation.

Performance improvements are sometimes delivered via wide area file services or WAN optimization.

question....!!!!!!!! us task

LENI FITRIANI(105610001)


1.what IP addres????

anwers:

"IP" stands for Internet Protocol, so an IP address is an Internet Protocol address. What does that mean? An Internet Protocol is a set of rules that govern Internet activity and facilitate completion of a variety of actions on the World Wide Web. Therefore an Internet Protocol address is part of the systematically laid out interconnected grid that governs online communication by identifying both initiating devices and various Internet destinations, thereby making two-way communication possible.

2.explain about the class of ip addressing class?
anwers:

• The first bit of class A IP address is 0, with a length of 8 bits net ID and host ID 24 bits long. So the first byte of the IP address class A has a range of 0-127. So in class A there are 127 networks with each network can accommodate about 16 million hosts (255x255x255). Class A IP address given to the network with a very large number of hosts, 
• Two bits of a class B IP address is always set to 10 so the first byte is always a value between 128-191. Network ID is the first 16 bits and 16 bits are the host ID so that if any computer has the IP address 167.205.26.161, the network ID and host ID = 167 205 = 26 161. On. Class B IP address has IP range from 128.0.xxx.xxx to 191.155.xxx.xxx, which amounted to 65 255 network by the number of hosts per network host 255 x 255 or about 65 thousand hosts.
• Class C IP address originally used for small networks such as LANs. The first three bits of a class C IP address is always set to 111. Network ID consists of 24 bits and 8 bits of remaining host ID so it can be formed about 2 million networks with each network has 256 hosts.
• Class D IP address used for multicasting. The first four bits of a class D IP address is always set 1110 so the first byte ranges between 224-247, while the next bit is set as required using the IP multicast group address. In multicasting is not known the term network ID and host ID
• Class E IP address is not made ​​available for public use. The first four bits of the IP address of this class is set 1111 so the first byte ranges between 248-255.

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LAN

LAN

A LAN (local area network) is a group of computers and network devices connected together, usually within the same building. By definition, the connections must be high speed and relatively inexpensive (e.g., token ring or Ethernet). Most Indiana University Bloomington departments are on LANs.

Local area networks (LANs) are computer networks ranging in size from a few computers in a single office to hundreds or even thousands of devices spread across several buildings. They function to link computers together and provide shared access to printers, file servers, and other services. LANs in turn may be plugged into larger networks, such as larger LANs or wide area networks (WANs), connecting many computers within an organization to each other and/or to the Internet.

Because the technologies used to build LANs are extremely diverse, it is impossible to describe them except in the most general way. Universal components consist of the physical media that connect devices, interfaces on the individual devices that connect to the media, protocols that transmit data across the network, and software that negotiates, interprets, and administers the network and its services. Many LANs also include signal repeaters and bridges or routers, especially if they are large or connect to other networks.

The level of management required to run a LAN depends on the type, configuration, and number of devices involved, but in some cases it can be considerable.

A LAN connection is a high-speed connection to a LAN. On the IUB campus, most connections are either Ethernet (10Mbps) or Fast Ethernet (100Mbps), and a few locations have Gigabit Ethernet (1000Mbps) connections.

NAT

NAT

Network Address Translation ( NAT ) is the process of modifying IP address information in IP packet headers while in transit across a traffic routing device .

The simplest type of NAT provides a one to one translation of IP addresses. RFC 2663 refers to this type of NAT as basic NAT . It is often also referred to as one-to-one NAT . In this type of NAT only the IP addresses, IP header checksum and any higher level checksums that include the IP address need to be changed. The rest of the packet can be left untouched (at least for basic TCP/UDP functionality, some higher level protocols may need further translation). Basic NATs can be used when there is a requirement to interconnect two IP networks with incompatible addressing.

However it is common to hide an entire IP address space, usually consisting of private IP addresses , behind a single IP address (or in some cases a small group of IP addresses) in another (usually public) address space. To avoid ambiguity in the handling of returned packets, a one-to-many NAT must alter higher level information such as TCP/UDP ports in outgoing communications and must maintain a translation table so that return packets can be correctly translated back. RFC 2663 uses the term NAPT ( network address and port translation ) for this type of NAT. Other names include PAT ( port address translation ), IP masquerading , NAT Overload and many-to-one NAT. Since this is the most common type of NAT it is often referred to simply as NAT.

As described, the method enables communication through the router only when the conversation originates in the masqueraded network, since this establishes the translation tables. For example, a web browser in the masqueraded network can browse a website outside, but a web browser outside could not browse a web site in the masqueraded network. However, most NAT devices today allow the network administrator to configure translation table entries for permanent use. This feature is often referred to as "static NAT" or port forwarding and allows traffic originating in the "outside" network to reach designated hosts in the masqueraded network.

In the mid-1990s NAT became a popular tool for alleviating the consequences of IPv4 address exhaustion .  It has become a common, indispensable feature in routers for home and small-office Internet connections. Most systems using NAT do so in order to enable multiple hosts on a private network to access the Internet using a single public IP address.

Network address translation has serious drawbacks on the quality of Internet connectivity and requires careful attention to the details of its implementation. In particular all types of NAT break the originally envisioned model of IP end-to-end connectivity across the Internet and NAPT makes it difficult for systems behind a NAT to accept incoming communications. As a result, NAT traversal methods have been devised to alleviate the issues encountered.

IP ADDRESSING AND SUBNETTING

IP addressing

IP addresses are used as the address in the relationship between hosts on the internet so it is a universal communication system because it is an addressing method that has been accepted worldwide. By determining the IP address means that we have provided a universal identity for each interadce computer. If a computer has more than one interface (eg using two ethernet) then we must give two IP addresses for each computer for each interface.

2.Format IP Address

IP addresses consist of 32-bit binary numbers separated by a dot every 8 bits. Each 8 bits are called octets. IP address form can be written as follows:

xxxxxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx

So the IP address has a range of 00000000.00000000.00000000. 00000000 to 11111111.11111111.11111111.11111111. IP address notation with binary numbers like this difficult to use, so often written in the fourth decimal, each separated by 4 pieces point better known as "dotted decimal notation". Each decimal number represents the value of one octet IP address. 

3.Pembagian Class IP Address

The number of available IP addresses is theoretically 255x255x255x255 or about 4 billion more to be distributed to all users worldwide Internet network. The division of these classes are intended to facilitate the allocation of IP addresses, both for the host / network or for certain specific purposes.

IP addresses can be separated into two parts, namely the network (net ID) and the host (host ID). Net ID instrumental in the identification of a network from another network, while the host ID serves to identify a host within a network. Thus, all hosts are connected in the same network have the same net ID. Some of the bits of the early part of the IP Address is the network bits / network number, while the rest is for the host. The dividing line between the network and hosts are not fixed, depending on the class network. IP addresses are divided into five classes, namely class A, class B, class C, class D and class E. The differences of each class is on the size and number. For example class A IP network is used by few but the number of hosts that can be accommodated by each network is very large. Class D and E are not used in general, a class D is used for network multicast and class E for experimental keprluan. Internet Protocol software determines the division of this class by examining the first few bits of the IP Address. Determination of the class is done in the following ways:

• The first bit of class A IP address is 0, with a length of 8 bits net ID and host ID 24 bits long. So the first byte of the IP address class A has a range of 0-127. So in class A there are 127 networks with each network can accommodate about 16 million hosts (255x255x255). Class A IP address given to the network with a very large number of hosts, the IP of this class may be illustrated in the figure below:
• Two bits of a class B IP address is always set to 10 so the first byte is always a value between 128-191. Network ID is the first 16 bits and 16 bits are the host ID so that if any computer has the IP address 167.205.26.161, the network ID and host ID = 167 205 = 26 161. On. Class B IP address has IP range from 128.0.xxx.xxx to 191.155.xxx.xxx, which amounted to 65 255 network by the number of hosts per network host 255 x 255 or about 65 thousand hosts.
• Class C IP address originally used for small networks such as LANs. The first three bits of a class C IP address is always set to 111. Network ID consists of 24 bits and 8 bits of remaining host ID so it can be formed about 2 million networks with each network has 256 hosts.
• Class D IP address used for multicasting. The first four bits of a class D IP address is always set 1110 so the first byte ranges between 224-247, while the next bit is set as required using the IP multicast group address. In multicasting is not known the term network ID and host ID
• Class E IP address is not made ​​available for public use. The first four bits of the IP address of this class is set 1111 so the first byte ranges between 248-255.

In addition the term also known as Network Prefix, which is used to designate the IP address prefix is jaringan.Penulisan network with a slash "/" followed by numbers that indicate the network prefix length in bits. Eg to appoint a class B network 167.205.xxx.xxx used 167.205/16 writing. This is item 16 bits for the network prefix length of class B.

Special 4.Address

In addition to the address used for the host identifier, there are several types of addresses are used for special purposes and should not be used for the host identifier. Address is:

Network Address. Address is used to identify a network on the Internet network. Suppose for a host with a class B IP address 167.205.9.35. Without using the subnet (will be explained later), the network address of this host is 167.205.0.0. Address is obtained by making all the host bits in the two last segments to 0. The goal is to simplify the routing information on the Internet. Router enough to see the network address (167 205) to determine the router where the datagram should be sent. The analogy is similar to the process of mail delivery, the clerk at the post office sorters just look at the destination mail address (no need to read selutuh address) to determine which path should be taken of the letter.

Broadcast Address. This address is used to send / receive information that should be known by all hosts on a network. As is known, each IP datagram header has a destination address of IP addresses of hosts that will be addressed by the datagram. With this address, so only the destination host the datagram processing, while others will host it. What if a host wants to send datagram to all hosts in its network? Inefficient if he should make as much as the amount of replication datagram destination host. Bandwidth usage will increase and the host workload increases, the contents of the same datagram-datagram. Therefore, created the concept of a broadcast address. Host simply send to the broadcast address, all hosts in the network will receive the datagram. Consequently, all hosted on the same network must have the same broadcast address and the address should not be used as an IP Address to a particular host.

So, in fact each host has two addresses to receive a datagram: the first is the IP Addressnya that is unique and the second is a broadcast address on the network where the host is located.

Broadcast address is obtained by making the host bits in the IP Address to 1. So, for the host with IP address 167.205.9.35 or 167.205.240.2, its broadcast address is 167205255255 (two last segments of the IP Address 11111111.11111111 are valuable, so it is unreadable 255 255 decimal). The type of information is usually broadcast routing information.

Multicast Address. Address classes A, B and C is the address used for communication between hosts, which uses unicast datagram-datagram. That is, the datagram / ​​packet has a destination address of a particular host. Only hosts that have the same IP address with the destination address in the datagram that will receive the datagram, while others will host it. If the datagram is addressed to all hosts on a network, then the field will contain the destination address is broadcast address from the network in question. From these two modes of delivery (unicast and broadcast), there are also modes to three. Required a special mode if a host wants to communicate with multiple hosts at once (host group), with only sends one datagram only. But unlike the broadcast mode, only the host - the host who are members of a group who will receive this datagram, while the other hosts will not be affected. Therefore, introduced the concept of multicast. In this concept, all the groups that run the application with a single multicast address. Class structure of multicast addresses can be seen in Figure below.

For the purposes of multicast, a number of IP addresses allocated as a multicast address.If the structure follows the shape 1110xxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx IP Address (224.0.0.0 decimal form to 239 255 255 255), then the IP address is a multicast address. The allocation is intended for group purposes, not for the host as in class A, B and C. Members of the group is the host - the host who wants to join the group. Members are also not limited to the network on one subnet, but can reach the whole world. Because it resembles a backbone, then the network is muticast also known as the Multicast Backbone (MBONE

Primary Election 5.Aturan network ID and host ID

Here are the ground rules in determining the network ID and host ID is used:

• Network ID can not be equal to 127

127 by default network ID is used as a loopback address ie the IP address used by a computer to appoint himself.

• Network ID and host ID must not be equal to 255

Network ID or host ID 255 will be interpreted as a broadcast address. This ID is the address that represents the entire network.

• Network ID and host ID must not be equal to 0

IP address with the host ID 0 is defined as a network address. Network address is used to designate a jaringn not a host.

• Host ID must be unique within a network.

In a network there should be no two hosts have the same host ID.

6.Subnetting

For some reason relating to the efficiency of the IP Address, resolve problems and organizational network topology, network administrators usually do subnetting. The essence of subnetting is to "move" the dividing line between the network and host part of an IP Address. Some bits from the host is allocated a bit extra on the network. Address of the network according to the standard structure is broken down into several subnetworks. This method creates a number of additional networks, but reduced the maximum number of hosts in each network.

Subnetting is also done to overcome hardware differences and the physical media used in a network. IP routers can integrate various networks with different physical media only if every network has a unique network address. In addition, with subnetting, Network Administrators can delegate a host address settings throughout the department of a large company to each department, for simplicity in managing the overall network.

A subnet is defined by implementing the masking bits (subnet mask) to the IP Address. Structure similar to the structure of the subnet mask IP address, which consists of 32 bits divided into 4 segments. The bits of the IP Address that "covered" (masking) by subnet mask bits corresponding active and will be interpreted as network bits. Bit 1 in the subnet mask means to enable masking (on), while bit 0 is off (off). In this case, let us take a single IP address with the number of class A 44.132.1.20.

With the standard rule, the IP address of this network number is 44 and the host number is 132.1.20. The network can accommodate a maximum of more than 16 million hosts are connected directly. Suppose at this address will be implemented as much as 16-bit subnet mask 255.255.0.0. (Hexa = FF.FF.00.00 or binary = 11111111.11111111.00000000.00000000). Note that in the first 16 bits of the subnet mask is worth 1, while the next 16 bits 0. Thus, the first 16 bits of an IP subnet mask address that subject will be considered as network bits. Network numbers will be changed to 44,132 and the number of hosts to be 1.20. Maximum capacity of directly connected hosts on the network to around 65 thousand hosts.

Subnet mask above is identical to the standard IP Address class B. By applying the subnet mask on a single class A network, network 256 can be made ​​new with each capacity equivalent network subnet class B. The application of more distant subnets such as 255.255.255.0 (24 bits) in class A will produce a larger number of networks (more than 65 thousand network) with the capacity of each subnet for 256 hosts. Class C network can also be subdivided into several subnets by applying the subnet mask of such higher for 25-bit (255 255 255 128), 26-bit (255 255 255 192), 27-bit (255 255 255 224) and so on.

Subnetting made ​​during interface configuration. Application of the subnet mask in the IP Address will define two new pieces address, ie Network Address and Broadcast Address. Network address is defined by setting all the host bits worth 0, while the broadcast address by setting the host bits worth 1. As has been dijelasakan in the previous section, the network address is the network that is useful in routing information. A host that does not need to know the address all hosts in the network to another. The information needed was the address of the network will be contacted as well as the gateway to reach the network. Illustration of subnetting, network address and broadcast address can be seen in Table below.

IP Address	Network Address Standard	Subnet Mask	Interpretasi	Broadcast Address
44.132.1.20	44.0.0.0	255.255.0.0 (16 bit)	Host 1.20 pada               subnet  44.132.0.0	44.132.255.255
81.150.2.3	81.0.0.0	255.255.255.0 (24 bit)	Host 3 pada  subnet 81.50.2.0	81.50.2.255
167.205.2.100	167.205.0.0	255.255.255.128 (25 bit)	Host 100 pada Subnet 167.205.2.0	167.205.2.127
167.205.2. 130	167.205.0.0	255.255.255.192 (26 bit)	Host 130 pada  subnet 167.205.2.128	167.205.2.191

Subnetting is only valid on the local network. For the network beyond the local network, network numbers are identified according to standard fixed network number-class IP Address.

   

TRANSMISSION MEDIA AND 802.xx IMPLEMENTATION

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Media Transmission

Transmission media in accordance with its function is to bring the bit stream data from one computer to another, then the data transmission requires the transmission medium that will be used for transmission purposes. Each medium has certain characteristics, within the bandwidth, delay, cost, and ease of installation and pemeliharaanya.
Transmission medium is a physical path between transmitter and receiver in a data transmission system. Transmission medium can be classified as a guided (guided) and unguided (not guided). Both can occur in the form of electromagnetic waves. With guided media, the wave is guided through a dense media such as twisted copper cable (twisted pair), coaxial copper cable and fiber optics. The atmosphere and the air is an example of unguided media, transmission form in this medium is referred to as wireless transmission.

Some fakor associated with the transmission media and signals as a determinant of the data rate and distance are as follows:
a. Bandwidth
The larger the signal bandwidth, the greater the data that can be handled.
b. Impairement transmission (transmission damage)
For guided media, twisted pair cable in general damaged transmission over the coaxial cable, and coaxial experienced it more than fiber optics.
c. Interference (Interference)
Interference of signals in frequency bands overlapping each other can cause distortion or could damage a signal
d. Number of recipient (receiver)
A guided media can be used to construct a point-to-point or a relationship that can be used together.
After knowing the factors associated with the transmission medium and can determine a suitable topology for the network to be built of course we need to know what equipment is needed in building a computer network. The media is needed in addition to the computer regardless of the type of network to be built are:
a. Cable
b. Wireless Transmission
c. Network Interface Card (NIC) or network card

= Types of Transmission Media
 
Guided Media (directional)
 
a. Cable
 
The cable network is a physical component of the most vulnerable and must be installed carefully and thoroughly, although the cable is not something that is so interesting and usually soon forgotten once completed installed. But once the network affected by the problem, then the cable is the first component being examined, because of the possibility of problems arising in this component.
 
Cables are classified into the guided transmission media. For guided transmission media, transmission capacity, in terms of bandwidth or data rate, depends critically on the distance and the state media are point-to-point or multipoint, such as Local Area Network (LAN). Three guided media are generally used for transmitting data is twisted pair, coaxial and fiber optic (fiber optic)
 
Cables can be said is that the major media networks in building a computer network including a network card. Because the two components without media components namely LAN expansion hub, we can build a small computer network using the BUS topology.
 
1. Twisted Pair
 
Is the simplest type of cable compared to the other and is currently the most widely used as a medium of cable in building a computer network.
 
• physical description
 
Twisted pair consists of two copper-sheathed wires arranged in such a way as to form a spiral pattern. One pair of wire serves as a communication link. In the farther distance, a bundle of twisted pair cable will be composed of hundreds of couples, the torsion of this cable will reduce the interference that occurs between the wires.
 
• Applications
 
At this time the most common transmission medium is twisted pair is used for both analog and digital communications. For analog communication, twisted pair is used for voice communications or telephone. Media that connects telephone terminals with LE (Local Exchange) is a twisted pair. For digital communications, media type is generally also used for digital signaling, connection to the digital data into digital switch or PBX to a building.
 
Twisted pair is often also used for data communications in a LAN (local). Data rate that can be handled by a twisted pair in data communications is about 10 Mbps, but in its development, current twisted pair has been able to handle the data rate of 100 Mbps. In terms of price, twisted pair is cheaper than the other two transmission media and more easily integrated in terms of its use. But in terms of distance and data rate that can be handled, twisted pair is more limited than others.
 
• Types of Twisted Pair
 
As with coaxial cable, twisted pair is also divided into 2 types of Unshielded Twisted Pair or better known by the acronym of UTP and Shielded Twisted Pair or STP. As the name implies clearly that the difference between the two lies in the shield or wrapper. At STP cable in which there is a protective coating of internal wires that protect data transmitted from the interference or disturbance.

 

Gambar 4.15  Kabel STP CAT5 / 1000 ft / 4 pair

UTP cable is much more popular than the STP and the most widely used as a wired network. UTP is specified by the organization EIA / TIA or the Electronic Industries Association and Telecommuniation Industries Association that categorizes UTP in 8 categories. You may have heard UTP CAT 5 and so on. It is one of the categories of UTP. The categories of UTP on the market today is a category 1, 2, 3, 4, 5 +, 6, 7. As for the difference in this category, especially in terms of transmission speed issues. In the first category or 1 can only transmit sound / voice just does not include data. In category 2, the maximum transmission speed of up to 4 Mbps. Category 3 to 10 Mbps, category 4 up to 16 Mbps, category 5 to 100 Mbps and paint 5 +, 6 and 7 was able to reach 1 Gbps or 1.000 Mbps.

Gambar 4.16  Kabel UTP CAT 5 /100m /4 Pair

Gambar 4.17  Kabel UTP CAT 5 /305m / 4 Pair

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Terjemahan

As an example of using UTP cable is a daily telephone cable, one of the main reasons why this type of UTP cable degan very popular compared to other cable types is due to the use of UTP cable as phone cable. Many buildings use this cable for telephone systems and usually no extra cables are installed to meet future development. Because of this cable can also be used to transmit data and voice, then an option to build a computer network. The only difference between a phone with a computer in the use of UTP cable is located on the jack or plug.

On computers that use RJ-45 can accommodate 8 cable connection while on the phone to use RJ-11, can accommodate 4 cable connections and smaller. More details can be seen that the connection from your phone using the RJ-11.

• Transmission Characteristics

For analog signal amplifier is required for each distance of 5 to 6 km. For digital signal repeaters are needed every 2 to 3 km.

• Advantages and Disadvantages

The advantage of using twisted pair media is in a computer network is the ease of installation and building a relatively cheap price. However, range and speed of data transmission on twisted pair is relatively limited. Addition, the media is easily affected by noise.

EIA / TIA (Electronic Industry Association / Telecommunication Industry Association) has made a standard UTP and categorized into 5 categories:

Categories of Unshielded Twisted Pair

type of Use
Category 1 Voice Only (Telephone Wire)
Category 2 Data to 4 Mbps (LocalTalk)
Category 3 Data to 10 Mbps (Ethernet)
Category 4 Data to 20 Mbps (16 Mbps Token Ring)
Category 5 Data to 100 Mbps (Fast Ethernet)


• Unshielded Twisted Pair Connector

Standard connector for UTP cable is a RJ-45 connector. This is a plastic connector that is similar to the telephone wall jack, but bigger. A slot is available to him make the RJ-45 can only be inserted one way.

Gambar 4.18  RJ-45 Connetctor CAT5e / Crimp Type

The downside of UTP is susceptible to electrical and radio frequency interference. STP suitable for use in environments with electrical interference; however, the extra shielding can make the cable become large. STP is often used on networks that use a ring topology.

2. coaxial

Today the coaxial cable is the most bnayak transmission medium used on a Local Area Network and a choice of many people because besides the price is cheap, cable type is also easy to use.

• physical description

Consists of two coaxial conductors, formed to operate on a large frequency band. Consists of the core conductor and surrounded by small wires. Among the conductors with the conductors surrounding a core separated by an insulator (jacket / sheld) as shown in the picture below

 

Gambar 4.19  Kabel Coaxial

Coaxial cables are less likely to interfere due to the shield. Coaxial can be used for long distances and support more terminals in a common pathway.

• Applications

The use of coaxial cables in general are:
- Antenna Television
- Long distance telephone transmission
- Link computers and
- LAN

• Types of coaxial cable

Coaxial cable is divided again into two parts, ie baseband coaxial cable (50 ohm cable) used for digital transmission and broadband coaxial cable (75 ohm cable) used for analog transmission.

• Coaxial Cable Baseband

This type of coaxial cable consists of copper wire as the hard core. Surrounded by an insulating material. This insulator is wrapped by a cylindrical conductor, which often takes the form of woven fabric. Outer conductor enclosed in a protective plastic sheath.

Construction and a protective layer of the coaxial cable provides a good combination of large bandwidth and excellent noise immunity. Bandwidth depends on the length of the cable. For cables over the length can actually be used, but will only achieve a lower data rate. Coaxial cable is widely used in telephone systems, but at this time for longer distances used type of fiber optic cable.

• Broadband Coaxial Cable

Other coaxial cable systems using analog transmission system with a standard cable television wiring. Such systems are called broadband. Due to the broadband network using a standard cable television technology, cable can be used up to 300 MHz and can operate nearly 100 miles in connection with analog signaling, which is much more secure than digital signaling.

To transmit digital signals on analog networks, the interface must be installed on any electronic device to change the outgoing bit stream into an analog signal and the incoming analog signal into a stream of bits.
An important difference between the baseband to broadband is that the broadband system covering a large area compared to the baseband system.

• Type coaxial cables

Coaxial cable is divided again into two types: thin (thinnet) and thick (thicknet). The difference is the thin cable is more flexible, easier to use and more importantly cheaper than thick cable. Thick cable is thicker and hard to bend and reach farther than the thin, which makes it more expensive. For comparison the thin cable range is 185 meters thick while cable coverage to reach 500 meters. Both types of cable uses the same components known as BNC (British Naval Connector) to connect the cable to the computer. BNC component form as shown in the figure below. Components of this include the BNC connector BNC cables, BNC T connectors, BNC connectors and BNC terminator barrel.

Gambar 4.20  BNC Coupler

Gambar 4.21  BNC 'T'

Gambar 4.22  BNC Terminator

 

Gambar 4.23  BNC Plug / Solder Type

• Transmission Characteristics
Coaxial can be used for both analog and digital signals. Because it is formed by using a shield then less likely to interfere and the occurrence of cross-talk. For the transmission of analog signals, needs to be given every few kilometers amplifiers. Spectrum which is used for signaling (signaling) is about 400 MHz. Thus for digital signals, repeaters are needed in every kilometer.

• Advantages and disadvantages

These cables are virtually unaffected noise and relatively cheap. However, the use of these cables easy hijacked. In addition, the type of thick coaxial is not possible to put in some kind of space.
 

  Optical fiber (optical fiber)

Fiber optics is one of the transmission medium that can deliver information with a large capacity with high reliability. Unlike other transmission media, then in fiber optics, carrier waves instead of electromagnetic waves or electricity, but light / laser light.

In fiber optics, digital signal transmitted data using light waves so it is quite safe for data transmission because it can not be on tap in the middle of the road, so the data can not be stolen in the middle of transmission. As with the cable such as coaxial and twisted pair. Another advantage of this optical fiber is in terms of speed (100 Mbps to 200.000 Mbps based on testing that has been done in the laboratory).

• physical description

Diameter optical fiber is very thin, between 2-125 um. Various glass and plastic materials can be used to make optical fiber material, the best and has the smallest loss is to use ultra-pure fiber Fused silican (more details look at the picture below.

fihure 4.24  cable Serat Optik

The material is very difficult to produce, because it was replaced by other materials that have a greater loss, but still tolerable mixture of plastic and glass materials. Fibre optic cylindrical and consists of 3 parts, core, cladding, and jacket. Core is the deepest and consists of one or more fibers. Each fiber is surrounded by cladding and then covered by the coating. The outer portion is separately charged with protecting jacket optical fiber from moisture, abrasion and damage.

• Applications

The difference between the use of optical fiber with twisted pair and coaxial cable, among others:

- Large capacity
2 Gbps data transmission can be performed within tens of kilometers, compared to the coaxial cable that can transmit data only a few Mbps in a maximum of 1 km or twisted pair is only up to 100 Mbps within tens of meters.

- Small size and lighter
Optical fiber diameter is smaller and lighter weight

- Low Attenuation
Attenuation is much lower compared with other wiring

- Isolation of electromagnetic
Optical fiber is not affected by electromagnetic fields outside the cable, not too fragile to noise or crosstalk.

- Repeater spacing greater
The distance between repeaters is greater, AT & T has fiber optics along the 318 km without repeaters, while the twisted pair or coaxial, repeaters placed every few meters.

• The main components

Optical fiber transmission system has three main components, namely the transmission medium, light sources and detectors. As the transmission medium used are very fine fibers of glass or fused silica. The light source can utilize Light Emitting Diode Laser Code or both of which emit pulses of light when electric current is given. As the photodiode detector is used, which serves to generate electrical pulses of light when there is a highlight. By combining an LED or laser diode to one end of optical fiber, it can be obtained undirected data transmission system that receives an electrical signal, convert and transmit a light pulse and convert the output back into an electrical signal at the receiving end.


• Characteristics of transmission

Optical fiber systems operate in areas with 100,000 to 1 million GHz. The working principle of optical fiber transmission are as follows:

The light from one source into a cylindrical glass or plastic cores

- File light is reflected and propagated along the fiber, while the part is absorbed by the surrounding material. Propagation in single mode provides better performance than multimode, each file took a route with different lengths and this led to the transfer time in the fiber causes signal elements to spread in time, so it can happen that the data received is not accurate. Since there is only one transmission path in a single mode of transmission, then the distortion will not occur. In fiber optic transmissions there are 3 types, namely single mode, multi mode and multi mode grade index.

- Two types of light sources used in fiber-optic system is the LED (Light Emitting Diode) and ILD (Injection Laser Diode). Both are semiconductor devices that will emit light when voltage is given. LEDs are more expensive types, can operate with a wider temperature range and have a longer operating time. This type of ILD, which operates on the principle of laser, more efficient and can forward data rate is greater. There is a link between the wavelength used, the type of transmission and the data rate that can be sent.




• The use of

Fiber optics can be very useful for transmission over varying distances. As an illustration, the distance that can be taken for data transmission on optical fiber is as follows:
- Long distance
For the telephone network, is 900 miles, with a capacity of 20,000 to 60,000 voice channels.
- Metropolitan
Located 7.8 miles and can accommodate 100 000-channel sound
- Regional rular
Located between 25 to 100 miles that connect the various cities
- Subscriber loop
                        Used to connect the central with direct customers.
- LAN
Used in local networks connecting inter-office
• Type of Fiber Optics
Based on the characteristic properties of the type of optical fiber can be broadly divided into two general categories:
- Multimode
In this type of fiber optic light propagation from one end to the other occurs through some streaks of light, as it is called multi-mode. Diameter of core (core) in accordance with the recommendations of the CCITT G.651 at 50 mm and is covered by a jacket sheath (cladding) with a diameter of 125 mm. While based on the composition of refractive index, multi-mode optical fiber has two profiles of graded index and step index.

In graded index fiber, optical fiber has a refractive index of light which is a function of distance to the axis / spindle fiber optics. Thus the light that radiates through multiple trajectories will eventually arrive at the other end at the same time. Unlike the graded index, then in step index optical fiber (having the same index of refraction of light), the rays are spread on the axis will arrive at the other end first (dispersion).

This can occur because the path through which the shaft is shorter than that experienced light reflection on the wall of the optical fiber. As a result of widening pulse occurs or in other words reducing the width of the field frequency. Therefore, practically only graded index optical fiber alone is used as a transmission channel multi-mode optical fiber.

- Single mode

Single mode optical fiber has a diameter or mono mode (core) is very small 3-10 mm, so that only one beam of light that can pass through it alone. Therefore only one beam of light then there is no influence of the refractive index of light travel, or the influence of differences in arrival time of light from one end to the other end (no dispersion). Thus the single mode optical fiber commonly used in fiber optic transmission systems remotely or out of town (long haul transmission system). While graded index used for the local telecommunications network (local network).
Comparison between multi-mode and single mode can be seen in the table below:
Table 4.2 Comparison of multi-mode and single mode
Bit Rate Distance Repeater
Multi Mode Distance Repeater
Single Mode
140 30 50
280 20 35
420 15 33
565 10 31

• Advantages and Disadvantages

Cables of this type are not affected by noise and can not be intercepted. But this cable is very expensive, difficult installation and the technology is still very expensive. In addition, the optical fiber in transmission has advantages over other transmission media, among others:

- A very small damping

Fiber optic telecommunications system having transmission attenuation per km is relatively small compared with other transmissions, such as coaxial cable or PCM, this means that the optical fiber is suitable for use in telecommunications over long distances, because it only requires fewer repeaters.

- The field frequency

In theory, optical fiber can be used with high speed, up to several gigabits / sec. Thus this system can be used to carry signaling information in large numbers only in single optical fiber is smooth.


- Small size and lightweight

Thus greatly facilitate the transport of the installation to the location. For example, can be fitted with a long cable, without having to make a new hole.

- There is no reference

This is due to optical fiber transmission systems use the light / laser light as a carrier wave. The result will be free from competent cross (cross talk) is often the case on regular cable. Or in other words the quality of telecommunications transmission or produced far better than with cable transmission. With no interference would allow fiber optic cables installed on high voltage electric power networks (high voltage) without fear of interference caused by high voltage.

For comparison of the three types of cable above, can be seen in the table below:

Table 4.3 Comparison of coaxial cable, twisted pair and fiber optic
Characteristics Thinnet Thicknet Twisted Pair Fiber Optics
Cost / price more expensive to more expensive than twisted thinnet Most expensive Most expensive
Range of 185 meters 500 meters 100 meters 2000 meters
Transmission of 10 Mbps 10 Mbps 1 Gbps> 1 Gbps
Less flexible flexibility flexible enough Most flexible is flexible
Ease of installation Easy installation Easy installation is very easy to Difficult
Resistance to interference Good / Good resistance to interference / resistance to interference Susceptible to interference Undeterred interference

2. Unguided media (not directional)

When two computers owned by a company / organization with its position close to one another need to communicate, often can be implemented easily by installing a cable between two computers. However, if the distance is far enough, or computer amounted to much, or the cord through the public streets, the cost of cabling to be a barrier, in addition to personal cabling that crosses (or planted) in public places is considered a violation of law. As a result, the designers of the network using multiple alternatives:

a. Using the Telephone Cable

Connections made using existing telecommunications facilities (in Indonesia is provided by PT. Telkom). As with other cables, telephone cables also often experience some problems, namely: attenuation, distortion, and delay.

Attenuation is the reduction in energy when the signal travels to its destination. When the attenuation terlau large, the receiver will not be able to detect the signal at all. To overcome this, the amplifier can be mounted in order to compensate for attenuation. However, this approach can only help it but have never been able to improve the signal in accordance with the original form.

Other disorders delay distortion. The distortion is caused by the difference Fourier components that run with different speed. For digital data, the rapid component of a single bit can capture and take over a slow first component of the bits, mix the two bits and increase the probability of acceptance is not true.

The third is a noise disturbance, which is not expected that the energy can come from sources other than the transmitter. Thermal noise due to random motion (random) electrons in the wires and can not be avoided. Conversations cross (CROs stalk) is caused by the induction between two wires that lie very close. Sometimes while talking on the phone, you hear other conversations in the background. That's called cross talk. Finally, there is also the impulses that caused noise markers on power lines or other causes. For digital data, impulse noise can eliminate one or more bits of information.

Based on experience, the use of wired LAN network using dial-up telephone connections often experience rupture caused by disturbances in the transmission cable. This problem becomes more complicated because of the improvements have to wait for a third party (in this case the PT. Telkom) which usually takes a long time. This problem can actually be overcome by providing a backup phone line, but this means additional cost burden of the company. Not to mention the cost of monthly phone bills which amount is not small.

b. Using Infrared and Millimeter Waves
The use of infrared as a transmission medium for communication of data began to be applied at close range on a variety of equipment such as televisions, mobile phones until the data transfer on the PC. These waves are relatively directional, inexpensive and easily made. But there are drawbacks: can not penetrate solid objects (try to stand between you and the television remote control and see if the device can function). On the other hand, the fact that the infrared system can not penetrate the wall of an advantage as well. This means that the infrared system in a room will not interfere with existing infrared systems in the surrounding space. In addition, infrared security against eavesdroppers better than the radio system. For this reason, it is not necessary government permits to operate the infrared system. Converse with radio systems that require government approval. Infrared communication can not be used outdoors because sunlight has the same bright infrared spectrum appears.

c. Transmission of Light Waves

Transmission is done by installing a laser beam as wide as 1 mm in the roof and direct it to the target width of 1 mm. But this requires zero skill. The disadvantage is that laser light can not penetrate rain or thick fog, but the laser can operate normally in sunny weather. However, although the weather is sunny, the heat emanating from the sun during the day led to rising convection currents on the roof of the building. This turbulent air will deflect the laser beam and make it spin in circles around the detector.

d. Radio Transmission

Radio waves is easy once made, can be spread over long distances. Because it used radio waves for communication both indoors and outdoors. That's why a portable radio can function well in the room. Radio waves can spread in omnidirectional, meaning that such waves may spread in different directions. Because it's physical position of the transmitter and receiver do not need to be regulated carefully. The nature of radio waves depends on frequency. With respect to the ability of radio waves that can spread far, the interference between two users is a problem. For this reason, all countries strictly supervise the users transmitter. When this has been a lot of vendors who sell packages Wireless LAN (WaveLAN) which uses radio transmission medium.
e. Technologies WaveLAN
Wireless LAN (WaveLAN) is a technology that allows users to access the LAN network without a cable media. WaveLAN can also be used to connect one location to another location without the LAN cable (wireless). Motivation and its main advantage is the increased mobility of network users can switch almost without restriction and access LANs from nearly anywhere.
Needed to build a wireless LAN client adapter installed on each client. WLAN ad hoc (or peer-to-peer) is the simplest configuration. In this configuration, all devices installed client adapter enough and can communicate directly.
For the number of client and network segment more (microcellular network) using a device access point that functions like a hub / bridge on an Ethernet network as well as the interconnection between the LAN. Some of the WaveLAN product on the market including Cisco, Teletronics, Samsung, D Link, Wave, Addtron and others.
Communication WaveLAN can use radio frequency (RF) or infrared (IF). RF is more commonly used than the IF because it has advantages in terms of coverage, coverage (coverage) and wide bandwidth.
RF operates on several frequencies including 2.4 GHz; 5.2 GHz and 5.7 GHz. Frequency of several options, the most widely used today is the WaveLAN 2.4 GHz (ISM band), which by the FCC (Federal Commission Commission) categorized free frequency licensing.
Frequency of 2.4 GHz actually has two types of transmission: frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS). Spread spectrum is a modulation technique that transmits broadband signals at radio frequencies. This technique is ideal for use in data communications is more resistant to noise and radio interference. FHSS bandwidth is limited only up to 2 Mbps, while the DSSS can achieve 11 Mbps. So that the wireless LAN applications at this time many uses DSSS technology.
The diversity of WaveLAN technology raises the need for standardization. World standards bodies IEEE (Institute of Electrical and Electronic Engineers) has made the standardization of Ethernet as the technology. IEEE 802.11b interoperability standards for the frequency is 2.4 GHz with a bandwidth of 11 Mbps (using DSSS technology). While the IEEE 802.11a is for the frequency of 5 GHz with a maximum bandwidth of 54 Mbps.
Standard includes all the standard security algorithms used Wired Equivalent Privacy (WEP). WEP is a security protocol designed to transfer security to the WaveLAN with a level of security and privacy as the base network cable. WEP will mengekripsi (scrambles) the data are transferred in a wireless network, which prevents access to users who are not members of the LAN.
Antargedung
The presence of WaveLAN has redefined the meaning of 'local' on the LAN. Unlike the wired LAN that only reach a maximum of 100 m (UTP cable) or 500 m (coaxial cable), the emission of radio waves can reach up to tens of kilometers. If the previous location is usually a connection between the LAN infrastructure WAN (Wide Area Network), a wireless alternative to this is not necessary anymore. By using the BTS and RF antenna's reach can reach 35 km.
With that range, allowing to build a LAN connection antargedung (building-to-building) with a single LAN. Just compare if we choose a WAN solution, it needs an additional device (router, modem), the cost of rental links, licensing, and installation time is quite long. Wireless solutions will reduce infrastructure costs, license fees, rental fees and the canal is much faster installation time.

Excellence
WLAN solution provides many advantages over cable technology. In terms of cost, this solution is the most economical. The cost of installation and devices will have a lot on the market at affordable prices. WLAN customers pay only the cost of any connection to the ISP, without thinking about cost of the phones. For the ISP is also very beneficial because they do not need to lease or permit E1 connection to Telkom for the use frequency is 2.4 GHz license-free.
Flexibility, the ease of access to the network while the cable can not reach, ease of movement and ease of configuration changes and install.
Scalability, ie the ease of development and the addition of network nodes. The concept of home office has become easy and inexpensive.
Mobility, which allows users to access mobile networks (mobile).
Multi Application, Infrastructure WaveLAN can use a variety of applications. Through a wide bandwidth enables applications laid IP applications that require QoS (Quality of Service) such as voice, teleconferences and multimedia.
Performance
WaveLAN performance depends on the knowledge of installation and user density in one area. Poor understanding of the WLAN installers frequency technology, the installation of devices is often done carelessly that eventually led to ketidakhandalan / instability of the transmission network. Transmission errors become larger with the result that the transmission process becomes slow.
User density factor (density) in an area often also cause low wireless performance. Due to the lack of clarity of rules on the use of a frequency of 2.4 GHz and the lack of knowledge about the frequency, resulting in lines 2.4 GHz strongly contested by''race''between the transmitter. As is often experienced in some cities such as Yogyakarta, Bandung

4.3 Types Transmission

This type of signal transmission of data or information in a medium of communication can be grouped into two parts, namely the transmission of parallel and serial transmission.

4.3.1 Parallel Transmission

In parallel transmission, a single connector which consists of seven or eight bits (ASCII) are transmitted simultaneously at any time. For example when used ASCII code, then it takes as many as eight channels to transmit 8 bits at once for a single character ASCII code.

In this parallel transmission is transmitted in parallel is the bits that represent a single character, while each character transmitted serially.
Parallel communications used for communication at close range, usually the transmission type is used to transmit signals inside the computer or between computers to the printer.
Delivery with parallel transmission mode has a high speed, because at every moment can be directly transmitted one character. However, this transmission mode requires a special cable that consists of several lines that will be used in shipping the bits of the character.

4.3.2 Serial Transmission

Serial transmission is a form of transmission that are generally used. In this serial transmission, each bit of a character are sent sequentially, ie bits per bit, where one bit is followed by the next bit (see picture). In this system, the receiver will collect the number of bits (for the system ASCII = 8 bits) sent by the transmitter to then be used as a single character.

Serial transmission can be grouped in three forms, namely synchronous transmission, asynchronous transmission and isochronous transmission. Further forms of serial transmission will be discussed one by one.

4.3.2.1 Synchronous Transmission

Synchronous transmission is a form that transmits serial transmission of data or information continuously. Transmission of this type often face problems, namely problems sinkroniassi bit and character synchronization (see figure)
The main problem of synchronization is a matter of time when the transmitter began to put the bits to be transmitted to the transmission medium and the receiver knows exactly when to take the bits to be sent these.
Maslaah this can be overcome with a clock in the transmitter and receiver clock at. Clock at the transmitter will tell when to put the bits to be transmitted, for example if you want to send with a capacity of 100 bps, the clock at the transmitter is set to work with a clock speed of 100 bps and the receiver must also diatus to take from the transmission line 100 each time second.

The second problem in synchronous transmission is character synchronization. This problem of determining the number of bits which are the bits forming a character. This can be overcome by giving SYN character. Generally two or lebh tranmsisi SYN control is placed in front of the block of data transmitted.
When only used a transmission control character false synchronization errors can occur.

To prevent false synchronization, two control characters SYN can be used at the beginning of the block of transmitted data. identify the forms of SYN receiver after the first, then identify the next 8 bits, if a SYN control the second character, then after it starts counting every 8 bits and assemble into a character.

Asynchronous transmission is a transmission form in transmitting serial data or information not be continuous, where the transmitter can mentransmikan characters at different time intervals or in other words not necessarily in sync time between sending a single character with next character.
Each character is transmitted as a stand-alone entity and the recipient must be able to recognize each character. To overcome this, each character starts one additional bit, the start bit is a bit value of 0 and stop bits are a bit value of 1 is placed at the end of each character.
Asynchronous transmission is more secure than the synchronous transmission. In asynchronous transmission, when an error occurs in the transmitted data, will only destroy a block of data. However, asynchronous transmission is less efficient because it requires additional bits for each character that is the start bit and stop bit.

4.3.2.3 Transmission isochronous

Transmisison isochronous transmission is a combination of asynchronous and synchronous transmission. Each shipment will be prefixed with the character start bit and ends with a stop bit, but between the transmitter and receiver synchronized at the time of sending data continuously. Synchronization occurs at a specific time unit (see picture).

4.4 Method of transmission

A network can also be distinguished by the transmission method used in the process of sending data. In general, methods of transmission are often used include baseband and broadband.
4.4.1 Baseband
In this method, the data in the form of a direct digital signal transmitted over a single transmission medium such as cable channels without undergoing any change. In this way, then the data transmission depends on the transmission distance and quality of media used (Figure 4.34).
In this baseband method, it takes multiplexing equipment called Time Division Multiplexing (TDM). Using multiplexing equipment is then:
a. save the cost of use of communication channels
b. communication channel capacity can be utilized to the maximum extent possible
c. there is a possibility of some terminals do transmission of data to a common point.

TDM is used for transmitting data in the form of signals. With the TDM data transmission is done by managing the delivery of data from each terminal based on time (Figure 4.34). Each terminal was allotted delivery time, when time is up then turn given to the next terminal. And so on until all the terminal gets a turn to transmit, then given another turn to the first terminal. This process takes place quickly, so as if all the stations can transmit data at the same time. Therefore we need high-quality transmission medium yag, can transmit data at high speed multiplexer between the transmitter and receiver multiplexers.

The advantage of this baseband transmission system are:
a. low cost, because the system is not required modem
b. form of simple technology
c. easy installation and maintenance

In addition to the above profit-making, there are some drawbacks of baseband systems, namely:
a. Data transmission capacity is very limited because there is only one cross
data, so that only one pair of computers that can communicate at the same time.
b. Electrical signal traveling distance is limited
c. Ground cable connection is rather difficult
d. For large area needed expensive installation costs

4.4.2 Broadband

This method is used to transmit analog signals. So, if in the form of a digital signal must first be modulated analog signal.
Media used form of broadband coaxial cable (using medium frequency radio or satellite). Data from several terminals can use a single channel, but frequency varies, so that at the same time can be delivered several types of data over multiple frequencies.

advantage of broadband transmission system are as follows:

a. Data transmission capacity is quite high, because it has some transmission lines
b. For non-cable broadband systems, wider coverage area with a relatively cheaper cost.

Besides the above advantages can be exploited, there is some lack of broadband systems, namely:

a. Prices mode that required a relatively expensive
b. Trip delay time signal doubled compared with the time delay baseband signals travel on the system, because the modulation signal to be done first.
c. The process of installation and maintenance is quite large
d. For non-wired transmission media, the price is expensive relative frequency

4.5 Transmission Unit

A very important aspect in data communications is the speed of data transmission through the transmission medium. Factors that play a role in determining the maximum speed, among others are:

a. Quality track tranmsisi
b. The length of the connection
c. Electrical properties and
d. Type of modem

Quality of the transmission path indicated by the bandwidth. Bandwidth indicates the size of the capacity of transmission lines are expressed in units of:

a. Baud (Bd) is the velocity modulation
b. Bits per second (bps) is the speed signal
c. Characters per second (cps) is the transmission speed

Associated with the modulation speed of traffic on the transmission path. Speed ​​element in the path tranmsisi information expressed in one baud (elements per second). Basically this speed shows a maximum speed of the transmission line conditions change. One element equal to the number of bits per second can be transmitted in the transmission path.

Here are two examples of calculation of the transmission speed:

a. A terminal start / stop signal operates with a relatively slow speed, 110 bps. At this speed modem that transmits setiao used bits as a single element. Therefore, the modulation speed is 110 baud. In this example, each character consists of 11 bits (1 start bit, 7 data bits, 1 parity bit and 2 stop bits) sehigngga tramsmisinya speed is 110 bps: 11 bits = 10 cps.

b. A terminal has a synchronous speed of 2400 bps signal. For example it is assumed that the width of baud are not sufficient to maintain this speed. Therefore, modulation is used which combines the two bits into one element, in order to obtain the modulation speed of 1200 baud. So in this transmission, one character consists daru 8 bits (7 data bits and 1 parity bit), then the transmission speed is 2400 bps: 8 bits = 300 cps)

4.6 The capacity of transmission lines

The capacity of transmission lines can be classified into three groups based on their capacity, namely:

a. Narrowband Channel (Grade Subvoice Channel)
speed signal on the transmission line is 50-300 bps. Transmission of this type requires a relatively low installation costs, but the overhead is relatively expensive with a fairly large error rate.

b. Voiceband Channel (Voice Grade Channel)
Speed ​​signal on the transmission line is 300-500 bps. Transmission line is divided into two groups, ie dial-up (switched lines) and private lines (leased line). Dial up is the communication channel is obtained by using the telephone network. Before the relationship occurs, the user must dial a phone number to be addressed. While the private line is a line that uses the telephone network, but using special facilities so that it can be used by Telkom.

c. Wideband Channel
Speed ​​signal transmission in this type of transmission can reach millions of bps, eg coaxial cable, microwave and others.

Implementasi 802.1x

System Requirements
To implement a system of 802.1x on a wireless network, then the required specifications as follows.
1. Access Point (AP) that supports WPA/WPA2 (Example: SMCWBR14-G).
2. Wireless Adapter that supports WPA/WPA2 for authentication client (Supplicant).
3. One computer server for back-end authentication server (RADIUS server).
As for the OS used is Linux Debian Etch, and mechanisms to be applied is EAP-TLS
because it feels very safe for the private network.

Installing and Configuring the RADIUS Server
RADIUS can be used there are many, including FreeRADIUS, GNU Radius, JRadius, Open Radius, IAS, RadiusNT
& RadiusX, and much more. In this implementation freeradius used for back-end authentication server. on
Debian distribution, has included the distribution of FreeRADIUS. It's just that freeradius does not support TLS, so that
we need to reset itself in order to compile the TLS support. For FreeRADIUS source code can be downloaded at
http://www.freeradius.org. Do not forget to install libssl-dev compalingnya later that the results support TLS.
apt-get install libssl-dev
To compile FreeRADIUS as usual with the command
. / configure
Make
make install
Once completed and no errors, then the resulting distribution will be installed to the directory / usr / local /.
Before setting up, try running the following command.

root@tomiko:~# radiusd -X

Starting - reading configuration files ...

reread_config: reading radiusd.conf

Config: including file: /usr/local/etc/raddb/proxy.conf

Config: including file: /usr/local/etc/raddb/clients.conf

Config: including file: /usr/local/etc/raddb/snmp.conf

Config: including file: /usr/local/etc/raddb/eap.conf

Config: including file: /usr/local/etc/raddb/sql.conf

.

.

.

Module: Loaded radutmp

radutmp: filename = "/usr/local/var/log/radius/radutmp"

radutmp: username = "%{User-Name}"

radutmp: case_sensitive = yes

radutmp: check_with_nas = yes

radutmp: perm = 384

radutmp: callerid = yes

Module: Instantiated radutmp (radutmp)

Listening on authentication *:1812

Listening on accounting *:1813

Ready to process requests.

FreeRADIUS configuration for EAP-TLS
To configure FreeRADIUS to be used with EAP-TLS mechanism, then that needs to be done first
times is to make the certificate. FreeRADIUS has been included on the distribution of scripts to create the necessary certificates.
The script contained in the freeradius source directory, in the script directory. There are two scripts that can be used
to create a certificate, ie CA.certs and CA.all. To CA.certs is a script that is not interactive, so
we need to edit its configuration. As for CA.all, is an interactive script. And if you want to make
alone it can be read in http://www.urbanwireless.co.nz/?page_id=22. Here's the output from CA.certs.root@tomiko#sh CA.certs

##################

create private key

name : name-root

CA.pl -newcert

##################

Generating a 1024 bit RSA private key

................++++++

......................++++++

writing new private key to ’newreq.pem’

-----

You are about to be asked to enter information that will be incorporated

into your certificate request.

What you are about to enter is what is called a Distinguished Name or a DN.

There are quite a few fields but you can leave some blank

For some fields there will be a default value,

If you enter ’.’, the field will be left blank.

-----

Country Name (2 letter code) [AU]:

State or Province Name (full name) [Some-State]:

Locality Name (eg, city) []:

Organization Name (eg, company) [Internet Widgits Pty Ltd]:

Organizational Unit Name (eg, section) []:

Common Name (eg, YOUR name) []:

Email Address []:

##################

create CA

use just created ’newreq.pem’ private key as filename

CA.pl -newca

##################

CA certificate filename (or enter to create)

##################

exporting ROOT CA

CA.pl -newreq

CA.pl -signreq

openssl pkcs12 -export -in demoCA/cacert.pem \

-inkey newreq.pem -out root.pem

openssl pkcs12 -in root.cer -out root.pem

##################

MAC verified OK

##################

creating client certificate

name : name-clt

client certificate stored as cert-clt.pem

CA.pl -newreq

CA.pl -signreq

##################

Generating a 1024 bit RSA private key

...........................................++++++

..++++++

writing new private key to ’newreq.pem’

-----

.

.

.

.

dst

From the command will be generated some pretty important files cacert.pem and client_cert.p12 namely the keduakeduanya
later must be installed on the client / Supplicant.
To configure FreeRADIUS server, then there are two files that need to be edited is clients.conf and eap.conf. because FreeRADIUS
compiled re-used then the configuration file will be in / usr / local / etc / raddb. Here are the contents of
each configuration file.File eap.conf

eap {

default_eap_type = tls

timer_expire = 60

ignore_unknown_eap_types = no

cisco_accounting_username_bug = no

tls {

private_key_password = rahasiasaya

private_key_file = ${raddbdir}/certs/server_keycert.pem

certificate_file = ${raddbdir}/certs/server_keycert.pem

CA_file = ${raddbdir}/certs/cacert.pem

dh_file = ${raddbdir}/certs/dh

random_file = ${raddbdir}/certs/random

fragment_size = 1024

include_length = yes

}

}

File: clients.conf

client 202.46.129.0/26 {

secret = itsnet

shortname = itsnet

nastype = other

}

When finished, then try running the command radiusd-X. If no errors then FreeRADIUS configuration has been completed
carried out.root@tomiko:/usr/local/etc/raddb# radiusd -X

Starting - reading configuration files ...

reread_config: reading radiusd.conf

Config: including file: /usr/local/etc/raddb/proxy.conf

Config: including file: /usr/local/etc/raddb/clients.conf

Config: including file: /usr/local/etc/raddb/snmp.conf

Config: including file: /usr/local/etc/raddb/eap.conf

Config: including file: /usr/local/etc/raddb/sql.conf

.

.

.

.

Module: Instantiated radutmp (radutmp)

Listening on authentication *:1812

Listening on accounting *:1813

Ready to process requests.

Configuring the Access Point
For the access point used SMCWBR14-G that supports EAP-TLS, and EAP-MD5. Because EAP-MD5 does not
longer natively supported olehWindows XP SP2 starts, it uses EAP-TLS for authentifikasinya mechanism.
That need to be configured on the access point is a DHCP (if the access point support) and the RADIUS server.

Gambar 5:Configuring Radius Server

Gambar 6: Configuring DHCP

Configuring Client (Windows XP and above)
For EAP-TLS authentication mechanism, then the client needs to dinstall certificate CA Certificate is required
(root.der), the client certificate (cert-clt.p12) and the server certificate (cert-srv.p12). To install the CA certificate of the residence
Just click on the file root.der and the following window will appear

Gambar 7: CA sertifikat

Window that appears will inform the detail of the certificate. To install the certificate then click "Install Certificate",
will display a confirmation that the certificate will be installed. Click next and will show up window
the following.

Image 8: Location Instalasi

Select "Place all certificates in the following store" and click browse and select the "Trusted Root Certification Authorities".
After that click next and final confirmation will appear on the certificate and its installation location. Click the finish.
To install client certificates and server certificates are also using the same steps, except that the election
location has been selected "Automatically select the certificate store based on the type of certificate".
After all the certificates installed then the client is ready to use WPA with EAP-TLS mechanism.
4 testbed
In this tesbed will use IBM i-Series laptops with PCMCIA card D-LINK DWL-G65 AirPlusG + +. to be able to
it is necessary to configure an existing profile on the wireless LAN client / Supplicant. After opening the wireless connection
and open the "view wireless connection available" it will get the following display.

image 9: View Wireless Connection Available

In the picture can be seen that WPA security is applied at the access point with essid SMCass. next select the
"Change advanced settings" and select the tab "Wireless Network". In the "Preferred Network" essid is selected to be
we use to connect, then click "Properties" button.

image 10: Wireless Network

After that will appear as shown below. On the tab "Association" no option "Network Authentication"
and "Data encryption". For the "Network Authentication" is selected WPA and for "Data encryption" is selected TKIP

.

image 11: Wireless Network Properties

Next select the certificate for authentication. Select the tab "Authentication", then select the type of EAP (EAP Type) type
"Smart Card or other Certificate". Then select the certificate in accordance with the previously installed.

image 12: Memilih sertifikat

Wireless profile configuration has been completed. Client / Supplicant can perform authentication with EAP-TLS method.
At the time pass authentication it will show the image as follows

Gambar 13: Koneksi