ps2cho
07-31-05, 04:04 AM
Hey guys, i started writing up a few things that you guys might find interesting if you want to start learning about networking and how it works. I learnt all of this from the CISCO networking courses and nothing below is taken from any site. Let me know what you think so far, possibly you could add anything missing or correct any mistakes?
Thanks :) Enjoy.
EDIT: Well a great start, i put the title wrong rofl. Could any admins change it to Fundamentals of Networking please? Or just delete the thread?
Learning The Fundamentals Of Networking
Network is described as the connection of any collection of computers, printers, routers, switches, and other devices for the purpose of communication over some transmission medium.
Ok lets start with a few terms that you will need to understand before continuing. I will go into greater
depths when the time comes around, so just understand what each abbreviation stands for right now.
Do not worry if you do not understand what each term means.
ARP : Address Resolution Protocol.
AARP : AppleTalk Address Resolution Protocol.
AC : Alternating Current.
ACK : Acknowledgment.
Attenuation : To reduce (the amplitude of an electrical signal) with little or no distortion.
Bandwidth : The rated throughput capacity of a given network medium or protocol.
Baseband : A network technology where only one carrier frequency is used. An example is Ethernet.
Best-Effort Delivery : Describes a network that does not use a complex ACK system to guarantee reliable delivery of data.
Binary : A number system where the only characters used are 1 and 0. 1=on and 0= off.
Bit : A binary digit used in the binary numbering system.
Bits Per Second : Abbreviated as bps
BRI : Basic Rate Interface.
Bridge : A networking device that directs packets between two networks that use the same protocols. A Bridge operates at layer 2 of the OSI model. A bridge can filter, forward or flood an incoming frame based on the MAC address of that frame.
Broadband : A transmission system that multiplexes multiple independent signals onto one cable. This can be used when talking about a coaxial cable where analog signaling is used. Contrasts with Baseband.
Broadcast Address : The special address for sending a message to all stations.
Bus Topology : Linear LAN architecture in which transmissions from the network stations propagate the length of the medium and are received by all the other stations. One of topology's such as Ring, Star and Tree Topology's
Byte : A series of consecutive binary digits. There are 8 Bits in a Byte
Checksum : A method for checking the quality of the data that is being transmitted.
Client : A user, device or software program that requests services from a server.
Coaxial Cable : A typical high speed medium used typically in LANS. There are two types of coaxial cable: The 50-ohm cable, which is a digital signal and the 75-ohm cable which used an analog signal and high-speed digital signaling
Collision : A problem that occurs on a LAN network where frames from two nodes transmit at the same time and are damaged on route when they meet on the physical media.
Collision Domain : Same as Collision above. Repeaters/Hubs cause collisions to occur, while Switches, Bridges and Routers do not increase collision domains.
Connectionless : A term which means that the data that is being transferred without the existence of a virtual circuit. Refer to virtual circuit.
Connection-Oriented A term which means that the data that is being transferred requires a connection with a virtual circuit. Refer to virtual circuit.
Crosstalk : Interfering energy transferred from one circuit to another.
Datagram : A logical grouping of information sent as a network layer unit over the networks medium that does not establish a virtual circuit. An example of a datagram is an IP Datagram.
Data-Link Layer : Layer 2 of the OSI reference model. This layer basically provides reliablity of data across a physical link. The Data-Link layer deals with physical addressing, network topology, line discipline, error notification, ordered delivery of frames, and flow control.
Digital Signal : A type of electronic language which has only two characters: On and off which are indicated by a series of voltage pulses.
DoD : The abbreviation for the Department of Defense .
DNS : Domain Naming System. DNS is used to give names of network nodes, addresses.
Domain : A portion of the naming hierarchy tree that is to do with grouping networks based on organization-type or geography.
ESD : Electrostatic Discharge. A flow or spark of electricity from a static source
Ethernet : A Baseband LAN specification by Xerox Corporation. Runs at a variety of cable types at 10 Mbps. Also known as 10BASE2, 10BASE5, 10BASE-F, 10BASE-T.
Fast Ethernet : Any of a number of 100-Mbps Ethernets. Fast Ethernet is 10x faster compared to 10BASE-T Ethernets. Also known as 100BASE-FX, 100BASE-T, 100BASE-TX.
Fiber-Optic Cable : A physical medium which uses light transmission to send data down the cable. Fiber-Optic cable is more expensive than CAT5 or Coaxial cables. Fiber-Optic cabling ensures that there is no attenuation due to electromagnetic interference and is also runs at higher data rates.
FTP : File Transfer Protocol. A connection-oriented, Application protocol which is part of the TCP/IP protocol. Used to transfer files between two network nodes. More secure, but slower than TFTP.
Flow control : A technique to ensure that the data does not overwhelm the receiving device.
Frame : Logical grouping of information sent as a data link layer unit over a network medium.
Frequency : The number of cycles, measured in hertz, of an alternating current signal per unit time.
Full Duplex : Capability for simultaneous data transmissions between the sender and the receiver. Like a highway, it allows to send and receive at the same time, as compared to a one-way street which only allows one at a time.
GB : Gigabyte
GBps : Gigabytes per second
Gb : Gigabits
GHz : Gigahertz
Half Duplex : Compares to Full Duplex. Half Duplex is when only one direction of traffic can be sent and received at one time.
Handshake : A sequence of messages exchanged between two or more network devices to ensure transmission synchronization.
Hexadecimal : HEX. A number system using digits 0 through 9 and letters A through F. Abbreviation is HEX. HEX is Base16.
Hub : A network device which is a simple repeater. Hubs can be either passive or active. Active hubs repeat the signal that goes through them to strengthen the signal. Passive Hubs do not repeat and only separate the signal through the number of ports that the hub has.
IEEE : Abbreviation for the Institute of Electrical and Electronics Engineers.
IP Address : A 32-bit address that is assigned to the hosts that use TCP/IP. IP addresses have 5 classes. Class A,B,C,D or E. An IP has 5 octets separated with periods. An example would be 192.168.0.100
ISDN : Integrated Services Digital Network. A connection offered through your telephone line that can carry internet traffic. Usually faster than 56k/Dial up services.
ISO : International Organization for Standardization. This group developed the OSI reference model. This company have created a wide range of internet standards.
KBps : Kilobytes per second.
Kbps : Kilobits per second.
LAN : Local Area Network
Logical Address :
Loopback Test : A test in which signals are sent and directed back to where it was sent from to test for connection and other network interface usability’s.
MAC Address : Media Access Control Address. A address that is required to be a part of any NIC or networking device. MAC addresses are 6 bytes long and devices such as routers or switches use these MAC addresses to create its tables so that it can allocate the correct traffic down the correct port.
MAN : Metropolitan Area Network
NIC : Network Interface Card. The network device that allows system to communicate to the network.
OSI Reference Model : Open System Interconnection Reference Model. Consists of seven layers. This will be addressed later.
Packet : A logical grouping of information which includes a header which contains information and usually the user's data.
Routed Protocol : A protocol that can be routed by a router. The router must be able to interpret the logical internetwork as specified by that routed protocol. An example of a routed protocol include AppleTalk and IP.
Router : A layer 4 device which forwards packets from one network to another based on the information.
Routed Protocol : A protocol that routes through a specific routing algorithm.
Routing Table : A table created by for example a router or a switch that contains a list of the different routes in a network.
UDP : A connectionless transport layer protocol in the TCP/IP protocol stack. UDP is a simple protocol that exchanges data without ACK's or a guaranteed delivery. Faster than TCP.
SAN : Storage Area Network
UTP : Unshielded Twisted-Pair. Refers to CAT5 cabling where the wires do not have any shielding round them. The most commonly used medium on LAN networks. Cheap and reliable.
Virtual Circuit : A logical circuit which ensures reliable communication between two network devices such as a router or a switch.
VPN : Virtual Private Network
WAN : Wide Area Network - Anything outside your LAN
Window : The number of octets that the receiver is willing to accept.
Ok so those are the terms that i would recommend quickly reading over and referring back to if a word is used and you are not 100% sure the definition.
Learning The Very Basics Of Networking
The internet is the largest data network on the earth. Every network is interconnected.
For a connection to be established to the internet, it requires a physical connection, a logical connection and a program to display the results. The physical connection is completed by the NIC which allows the actual connection and transfer signal between the computers over your LAN or over your WAN. The logical connection uses standards called protocols. Protocols are basically a set of rules of how the connection will establish, maintain the connection and end it. The Transmission Control Protocol/ Internet Protocol or known more widely as TCP/IP, was created to forfil this. After all of this connecting and the like, it was to be viewed for the human eye right? We cant just read zeros and ones for information can we? A web browser is the most typical way to view what is being transmitted to your computer. Coding such as HTML will show all your graphics and text just like this webpage has your reading right now!
A NIC provides communication to and from the PC. For laptops, the most widely used is a PCMCIA Card (Personal Computer Memory Card International Association.) When choosing to purchase a NIC, you must make sure that the medium you are using on your network will actually work with the NIC. You wont be able to connect a Fiber-Optic cable to a CAT5 Ethernet Card for example. NIC's operate at anywhere from 10Mbps to 1000Mbps (Gb Ethernet).
Numbering/Base Systems
Computers use the binary number system or the Base 2 number system to represent data. Binary consists of ones and zeros (1 & 0.) ASCII uses binary digits to represent symbols on your keyboard. For example the A key is represented as an ASCII Value of 122. In Binary this is displayed as 01111010.
In a computer, one byte represents a single addressable storage location. These storage locations represent a value or single character of data, such as an ASCII code. The total number of combinations of the eight switches being turned on and off is 256. The value range of a byte is from 0 to 255. So a byte is an important concept to understand when working with computers and networks.
When a computer transmits a binary 0 it will be sent by 0 volts of electricity. When a binary 1 is sent, +5 volts of electricity are sent.
The Base 10 Number System
The most commonly used number system is the decimal or Base 10 numbering system.
Base 10 uses numbers 0 through 0 which can be combined together to create all possible numeric values. The Base 10 system uses powers of 10 to create its decimals.
So for example:
10^0 = 0,
10^1 = 10,
10^2 = 100,
10^3 = 1000,
10^6 = 10000 and etc...
Another example would be : 2134 = (2x103) + (1x102) + (3x101) + (4x100).
Base 2 Numbering System / Binary
The binary system uses base number 2 raised to a power or exponent. These values are placed in order with the lowest on the right. Here is how it looks:
2^7 --> 2^6 --> 2^5 --> 2^5 --> 2^4 --> 2^3 --> 2^2 --> 2^1
Or known as:
128 --> 64 --> 32 --> 16 --> 8 --> 4 --> 2 --> 1
So to put in an example. You want to find want to convert the decimal number 175 to a binary number you would do the following: (This is the easiest way to learn it)
Does 128 go into 175? Once. So start with a 1 as the first Binary Digit. So far you have the following:
1000000
Now minus 128 from 175 and you are left with 47.
Does 64 go into 47? It doesn't so put a 0 and leave the 47 you were left with alone.
Does 32 go into 47? Yes it does so put a 1 and minus 32 from 47.
47-32=15
We now have a binary that looks like this:
10100000
Does 16 go into 15? No it does not so put a 0 and leave it alone.
Now, Does 8 go into 15? Yes it does so another 1 and minus 8
15-8 = 7
Now the binary looks like this:
10101000
Does 4 go into 7? Yes it does so add another 1 and minus 4.
7-4 = 3
Does 2 go into 3? Yes so do the same
3-2 = 1
Does 1 go into 1? Yes course it does so add the last 1.
You have successfully completed your first Decimal to Binary conversion. Your Binary looks like this:
Decimal 175 = 10101111 Binary
Each bit of the binary is one bit and there are 8 bits! Remember this.
Right now you should test trying a different number. Another quick example would be Decimal Number 10. That would be in binary the following:
No 128's in 10.....No 64's in 10....No 32's in 10....No 16's in 10....Yes an 8....No 4's in 2.....Yes a two in 2....No 1's in 0.
The outcome would be: 00001010
That ends the Decimal --> Binary Conversion.
Binary to Decimal Conversion
This is even simpler than above :)
Very simply, count each of the 1's and add them together using there representation.
10000000 = 128
10000001 = 129
01000000 = 64
00001000 = 8
Remember the First octet = 128, the second = 64, Third = 32, Forth = 16, Fifth = 8, Sixth = 4, Seventh = 2, Eighth = 1
So give it a quick try now.
One more example would be:
10010101....128+16+4+1= 149 Decimal Number !
Easy huh = )
Hexadecimal Numbering System
The Hexadecimal Number System or HEX for short is a Base 16 numbering system. Hex numbers use 16 unique digits to display any combination of eight binary digits as only two hexadecimal digits, characters 0-9 and A-F .Most encryption on home networks use WEP which uses HEX as the primary encryption code.
Boolean/Binary Logic
Boolean login is used by routers to help determine the destination of packets. Boolean logic has seven Gates, but I am just going to cover three of these for now. The first Gate is the AND Gate. The AND Gate is a logic that a Router uses to help route packets to their destination and from their source. The second Gate is the NOT Gate. The NOT Gate simply changes a 0 bit to a 1 bit and a 1 bit to a 0 bit. The last Gate is the OR Gate. The OR Gate……….
CONTINUE LATER:::::: Could somebody explain this further?
IP Addresses and Layered Devices
The IP address
The IP address has 4 octets, with each octet containing 8 bits, just like above. IP Addresses are shown using the decimal number system but really are just binary coding.
For example: The IP address 68.109.65.100 is REALLY:
01000100 . 01101111 . 01000001 . 01100100
Get it why an IP Address is a 32-bit address? 4 octets = 32-bits!
Classes
For every IP address out there, it falls within a specific class. Every IP address has what’s known as a network address and a host address.
Network Part
This part specifies the unique number assigned to your particular network. It is also the part that identifies the class of network assigned. The network address identifies which class the IP falls under.
Host Part
This is the part of the IP address that you assign to each host, and uniquely identifies each host on your network. Note that for each host on your network, the network part of the address will be the same, but the host part must be different.
The classes go as the following:
A Class A network -> A range of 1-126.
A Class B network -> A range of 128-191.
A Class C network -> A range of 192-223.
A Class D network -> A range of 224-239. This class is not useable as they are reserved for later use
How to identify which class a IP belongs to
Very simply read the first octet and see where it falls under in the range I stated above. For example:
92.63.22.108
This is 92…so it would be a Class A network.
Another example:
201.198.0.1
This is Class C network.
Ok now that you know what class it’s under, this is how to identify what parts of the IP address are network and which parts are host.
If it is a Class A network, simply the first octet is locked. The rest of the IP are host numbers.
For example:
92.63.22.108
Like I used above, this would have only the 92 as the network part. 63.22.108 is the Host number.
If it is a Class B network, simply the first two octets are locked. The rest of the IP are host numbers.
For example:
150.2.8.1
This is indeed a class B network so 150.2 are the network parts and the 8.1 are host numbers.
If it is a Class C network, simply the first, second and third octets are locked. The rest of the IP are host numbers.
For example:
192.168.1.100
This is indeed a class B network so 192.168.1 are the network parts and the .100 is the host number.
Here is a table taken from http://www.idevelopment.info/data/Networking/Networking_Basics/BASICS_IP_Addressing_Scheme.shtml
Division of IP Address Space
+--------------------------------------------------------+
| Class | Range | Network Address | Host Address |
|--------------------------------------------------------|
| A | 0-127 | xxx | xxx.xxx.xxx |
| B | 128-191 | xxx.xxx | xxx.xxx |
| C | 192-223 | xxx.xxx.xxx | xxx |
+--------------------------------------------------------+
For every networking device, it is at a certain layer in the OSI model:
A Router lies as a Layer 3 Device
A Bridge lies as a Layer 2 Device.
A Switch lies as a Layer 2 Device. Some newer managed switches run at layer 3.
A NIC lies as a Layer 2 Device.
A Hub/Repeater lies as a Layer 1 Device due to its simplicity.
Thanks :) Enjoy.
EDIT: Well a great start, i put the title wrong rofl. Could any admins change it to Fundamentals of Networking please? Or just delete the thread?
Learning The Fundamentals Of Networking
Network is described as the connection of any collection of computers, printers, routers, switches, and other devices for the purpose of communication over some transmission medium.
Ok lets start with a few terms that you will need to understand before continuing. I will go into greater
depths when the time comes around, so just understand what each abbreviation stands for right now.
Do not worry if you do not understand what each term means.
ARP : Address Resolution Protocol.
AARP : AppleTalk Address Resolution Protocol.
AC : Alternating Current.
ACK : Acknowledgment.
Attenuation : To reduce (the amplitude of an electrical signal) with little or no distortion.
Bandwidth : The rated throughput capacity of a given network medium or protocol.
Baseband : A network technology where only one carrier frequency is used. An example is Ethernet.
Best-Effort Delivery : Describes a network that does not use a complex ACK system to guarantee reliable delivery of data.
Binary : A number system where the only characters used are 1 and 0. 1=on and 0= off.
Bit : A binary digit used in the binary numbering system.
Bits Per Second : Abbreviated as bps
BRI : Basic Rate Interface.
Bridge : A networking device that directs packets between two networks that use the same protocols. A Bridge operates at layer 2 of the OSI model. A bridge can filter, forward or flood an incoming frame based on the MAC address of that frame.
Broadband : A transmission system that multiplexes multiple independent signals onto one cable. This can be used when talking about a coaxial cable where analog signaling is used. Contrasts with Baseband.
Broadcast Address : The special address for sending a message to all stations.
Bus Topology : Linear LAN architecture in which transmissions from the network stations propagate the length of the medium and are received by all the other stations. One of topology's such as Ring, Star and Tree Topology's
Byte : A series of consecutive binary digits. There are 8 Bits in a Byte
Checksum : A method for checking the quality of the data that is being transmitted.
Client : A user, device or software program that requests services from a server.
Coaxial Cable : A typical high speed medium used typically in LANS. There are two types of coaxial cable: The 50-ohm cable, which is a digital signal and the 75-ohm cable which used an analog signal and high-speed digital signaling
Collision : A problem that occurs on a LAN network where frames from two nodes transmit at the same time and are damaged on route when they meet on the physical media.
Collision Domain : Same as Collision above. Repeaters/Hubs cause collisions to occur, while Switches, Bridges and Routers do not increase collision domains.
Connectionless : A term which means that the data that is being transferred without the existence of a virtual circuit. Refer to virtual circuit.
Connection-Oriented A term which means that the data that is being transferred requires a connection with a virtual circuit. Refer to virtual circuit.
Crosstalk : Interfering energy transferred from one circuit to another.
Datagram : A logical grouping of information sent as a network layer unit over the networks medium that does not establish a virtual circuit. An example of a datagram is an IP Datagram.
Data-Link Layer : Layer 2 of the OSI reference model. This layer basically provides reliablity of data across a physical link. The Data-Link layer deals with physical addressing, network topology, line discipline, error notification, ordered delivery of frames, and flow control.
Digital Signal : A type of electronic language which has only two characters: On and off which are indicated by a series of voltage pulses.
DoD : The abbreviation for the Department of Defense .
DNS : Domain Naming System. DNS is used to give names of network nodes, addresses.
Domain : A portion of the naming hierarchy tree that is to do with grouping networks based on organization-type or geography.
ESD : Electrostatic Discharge. A flow or spark of electricity from a static source
Ethernet : A Baseband LAN specification by Xerox Corporation. Runs at a variety of cable types at 10 Mbps. Also known as 10BASE2, 10BASE5, 10BASE-F, 10BASE-T.
Fast Ethernet : Any of a number of 100-Mbps Ethernets. Fast Ethernet is 10x faster compared to 10BASE-T Ethernets. Also known as 100BASE-FX, 100BASE-T, 100BASE-TX.
Fiber-Optic Cable : A physical medium which uses light transmission to send data down the cable. Fiber-Optic cable is more expensive than CAT5 or Coaxial cables. Fiber-Optic cabling ensures that there is no attenuation due to electromagnetic interference and is also runs at higher data rates.
FTP : File Transfer Protocol. A connection-oriented, Application protocol which is part of the TCP/IP protocol. Used to transfer files between two network nodes. More secure, but slower than TFTP.
Flow control : A technique to ensure that the data does not overwhelm the receiving device.
Frame : Logical grouping of information sent as a data link layer unit over a network medium.
Frequency : The number of cycles, measured in hertz, of an alternating current signal per unit time.
Full Duplex : Capability for simultaneous data transmissions between the sender and the receiver. Like a highway, it allows to send and receive at the same time, as compared to a one-way street which only allows one at a time.
GB : Gigabyte
GBps : Gigabytes per second
Gb : Gigabits
GHz : Gigahertz
Half Duplex : Compares to Full Duplex. Half Duplex is when only one direction of traffic can be sent and received at one time.
Handshake : A sequence of messages exchanged between two or more network devices to ensure transmission synchronization.
Hexadecimal : HEX. A number system using digits 0 through 9 and letters A through F. Abbreviation is HEX. HEX is Base16.
Hub : A network device which is a simple repeater. Hubs can be either passive or active. Active hubs repeat the signal that goes through them to strengthen the signal. Passive Hubs do not repeat and only separate the signal through the number of ports that the hub has.
IEEE : Abbreviation for the Institute of Electrical and Electronics Engineers.
IP Address : A 32-bit address that is assigned to the hosts that use TCP/IP. IP addresses have 5 classes. Class A,B,C,D or E. An IP has 5 octets separated with periods. An example would be 192.168.0.100
ISDN : Integrated Services Digital Network. A connection offered through your telephone line that can carry internet traffic. Usually faster than 56k/Dial up services.
ISO : International Organization for Standardization. This group developed the OSI reference model. This company have created a wide range of internet standards.
KBps : Kilobytes per second.
Kbps : Kilobits per second.
LAN : Local Area Network
Logical Address :
Loopback Test : A test in which signals are sent and directed back to where it was sent from to test for connection and other network interface usability’s.
MAC Address : Media Access Control Address. A address that is required to be a part of any NIC or networking device. MAC addresses are 6 bytes long and devices such as routers or switches use these MAC addresses to create its tables so that it can allocate the correct traffic down the correct port.
MAN : Metropolitan Area Network
NIC : Network Interface Card. The network device that allows system to communicate to the network.
OSI Reference Model : Open System Interconnection Reference Model. Consists of seven layers. This will be addressed later.
Packet : A logical grouping of information which includes a header which contains information and usually the user's data.
Routed Protocol : A protocol that can be routed by a router. The router must be able to interpret the logical internetwork as specified by that routed protocol. An example of a routed protocol include AppleTalk and IP.
Router : A layer 4 device which forwards packets from one network to another based on the information.
Routed Protocol : A protocol that routes through a specific routing algorithm.
Routing Table : A table created by for example a router or a switch that contains a list of the different routes in a network.
UDP : A connectionless transport layer protocol in the TCP/IP protocol stack. UDP is a simple protocol that exchanges data without ACK's or a guaranteed delivery. Faster than TCP.
SAN : Storage Area Network
UTP : Unshielded Twisted-Pair. Refers to CAT5 cabling where the wires do not have any shielding round them. The most commonly used medium on LAN networks. Cheap and reliable.
Virtual Circuit : A logical circuit which ensures reliable communication between two network devices such as a router or a switch.
VPN : Virtual Private Network
WAN : Wide Area Network - Anything outside your LAN
Window : The number of octets that the receiver is willing to accept.
Ok so those are the terms that i would recommend quickly reading over and referring back to if a word is used and you are not 100% sure the definition.
Learning The Very Basics Of Networking
The internet is the largest data network on the earth. Every network is interconnected.
For a connection to be established to the internet, it requires a physical connection, a logical connection and a program to display the results. The physical connection is completed by the NIC which allows the actual connection and transfer signal between the computers over your LAN or over your WAN. The logical connection uses standards called protocols. Protocols are basically a set of rules of how the connection will establish, maintain the connection and end it. The Transmission Control Protocol/ Internet Protocol or known more widely as TCP/IP, was created to forfil this. After all of this connecting and the like, it was to be viewed for the human eye right? We cant just read zeros and ones for information can we? A web browser is the most typical way to view what is being transmitted to your computer. Coding such as HTML will show all your graphics and text just like this webpage has your reading right now!
A NIC provides communication to and from the PC. For laptops, the most widely used is a PCMCIA Card (Personal Computer Memory Card International Association.) When choosing to purchase a NIC, you must make sure that the medium you are using on your network will actually work with the NIC. You wont be able to connect a Fiber-Optic cable to a CAT5 Ethernet Card for example. NIC's operate at anywhere from 10Mbps to 1000Mbps (Gb Ethernet).
Numbering/Base Systems
Computers use the binary number system or the Base 2 number system to represent data. Binary consists of ones and zeros (1 & 0.) ASCII uses binary digits to represent symbols on your keyboard. For example the A key is represented as an ASCII Value of 122. In Binary this is displayed as 01111010.
In a computer, one byte represents a single addressable storage location. These storage locations represent a value or single character of data, such as an ASCII code. The total number of combinations of the eight switches being turned on and off is 256. The value range of a byte is from 0 to 255. So a byte is an important concept to understand when working with computers and networks.
When a computer transmits a binary 0 it will be sent by 0 volts of electricity. When a binary 1 is sent, +5 volts of electricity are sent.
The Base 10 Number System
The most commonly used number system is the decimal or Base 10 numbering system.
Base 10 uses numbers 0 through 0 which can be combined together to create all possible numeric values. The Base 10 system uses powers of 10 to create its decimals.
So for example:
10^0 = 0,
10^1 = 10,
10^2 = 100,
10^3 = 1000,
10^6 = 10000 and etc...
Another example would be : 2134 = (2x103) + (1x102) + (3x101) + (4x100).
Base 2 Numbering System / Binary
The binary system uses base number 2 raised to a power or exponent. These values are placed in order with the lowest on the right. Here is how it looks:
2^7 --> 2^6 --> 2^5 --> 2^5 --> 2^4 --> 2^3 --> 2^2 --> 2^1
Or known as:
128 --> 64 --> 32 --> 16 --> 8 --> 4 --> 2 --> 1
So to put in an example. You want to find want to convert the decimal number 175 to a binary number you would do the following: (This is the easiest way to learn it)
Does 128 go into 175? Once. So start with a 1 as the first Binary Digit. So far you have the following:
1000000
Now minus 128 from 175 and you are left with 47.
Does 64 go into 47? It doesn't so put a 0 and leave the 47 you were left with alone.
Does 32 go into 47? Yes it does so put a 1 and minus 32 from 47.
47-32=15
We now have a binary that looks like this:
10100000
Does 16 go into 15? No it does not so put a 0 and leave it alone.
Now, Does 8 go into 15? Yes it does so another 1 and minus 8
15-8 = 7
Now the binary looks like this:
10101000
Does 4 go into 7? Yes it does so add another 1 and minus 4.
7-4 = 3
Does 2 go into 3? Yes so do the same
3-2 = 1
Does 1 go into 1? Yes course it does so add the last 1.
You have successfully completed your first Decimal to Binary conversion. Your Binary looks like this:
Decimal 175 = 10101111 Binary
Each bit of the binary is one bit and there are 8 bits! Remember this.
Right now you should test trying a different number. Another quick example would be Decimal Number 10. That would be in binary the following:
No 128's in 10.....No 64's in 10....No 32's in 10....No 16's in 10....Yes an 8....No 4's in 2.....Yes a two in 2....No 1's in 0.
The outcome would be: 00001010
That ends the Decimal --> Binary Conversion.
Binary to Decimal Conversion
This is even simpler than above :)
Very simply, count each of the 1's and add them together using there representation.
10000000 = 128
10000001 = 129
01000000 = 64
00001000 = 8
Remember the First octet = 128, the second = 64, Third = 32, Forth = 16, Fifth = 8, Sixth = 4, Seventh = 2, Eighth = 1
So give it a quick try now.
One more example would be:
10010101....128+16+4+1= 149 Decimal Number !
Easy huh = )
Hexadecimal Numbering System
The Hexadecimal Number System or HEX for short is a Base 16 numbering system. Hex numbers use 16 unique digits to display any combination of eight binary digits as only two hexadecimal digits, characters 0-9 and A-F .Most encryption on home networks use WEP which uses HEX as the primary encryption code.
Boolean/Binary Logic
Boolean login is used by routers to help determine the destination of packets. Boolean logic has seven Gates, but I am just going to cover three of these for now. The first Gate is the AND Gate. The AND Gate is a logic that a Router uses to help route packets to their destination and from their source. The second Gate is the NOT Gate. The NOT Gate simply changes a 0 bit to a 1 bit and a 1 bit to a 0 bit. The last Gate is the OR Gate. The OR Gate……….
CONTINUE LATER:::::: Could somebody explain this further?
IP Addresses and Layered Devices
The IP address
The IP address has 4 octets, with each octet containing 8 bits, just like above. IP Addresses are shown using the decimal number system but really are just binary coding.
For example: The IP address 68.109.65.100 is REALLY:
01000100 . 01101111 . 01000001 . 01100100
Get it why an IP Address is a 32-bit address? 4 octets = 32-bits!
Classes
For every IP address out there, it falls within a specific class. Every IP address has what’s known as a network address and a host address.
Network Part
This part specifies the unique number assigned to your particular network. It is also the part that identifies the class of network assigned. The network address identifies which class the IP falls under.
Host Part
This is the part of the IP address that you assign to each host, and uniquely identifies each host on your network. Note that for each host on your network, the network part of the address will be the same, but the host part must be different.
The classes go as the following:
A Class A network -> A range of 1-126.
A Class B network -> A range of 128-191.
A Class C network -> A range of 192-223.
A Class D network -> A range of 224-239. This class is not useable as they are reserved for later use
How to identify which class a IP belongs to
Very simply read the first octet and see where it falls under in the range I stated above. For example:
92.63.22.108
This is 92…so it would be a Class A network.
Another example:
201.198.0.1
This is Class C network.
Ok now that you know what class it’s under, this is how to identify what parts of the IP address are network and which parts are host.
If it is a Class A network, simply the first octet is locked. The rest of the IP are host numbers.
For example:
92.63.22.108
Like I used above, this would have only the 92 as the network part. 63.22.108 is the Host number.
If it is a Class B network, simply the first two octets are locked. The rest of the IP are host numbers.
For example:
150.2.8.1
This is indeed a class B network so 150.2 are the network parts and the 8.1 are host numbers.
If it is a Class C network, simply the first, second and third octets are locked. The rest of the IP are host numbers.
For example:
192.168.1.100
This is indeed a class B network so 192.168.1 are the network parts and the .100 is the host number.
Here is a table taken from http://www.idevelopment.info/data/Networking/Networking_Basics/BASICS_IP_Addressing_Scheme.shtml
Division of IP Address Space
+--------------------------------------------------------+
| Class | Range | Network Address | Host Address |
|--------------------------------------------------------|
| A | 0-127 | xxx | xxx.xxx.xxx |
| B | 128-191 | xxx.xxx | xxx.xxx |
| C | 192-223 | xxx.xxx.xxx | xxx |
+--------------------------------------------------------+
For every networking device, it is at a certain layer in the OSI model:
A Router lies as a Layer 3 Device
A Bridge lies as a Layer 2 Device.
A Switch lies as a Layer 2 Device. Some newer managed switches run at layer 3.
A NIC lies as a Layer 2 Device.
A Hub/Repeater lies as a Layer 1 Device due to its simplicity.