Networking 101

What is networking?

Networking is the practice of linking two or more computing devices together for the purpose of communicating and sharing data. Networks are built with a mix of computer hardware and computer software

Benefits of Networking

Networking adds a lot of flexibility in the way you work and spend time with your computers and electronic devices. With a network, you can:

• Share a high-speed, broadband cable or DSL Internet connection so everyone can surf the web simultaneously
• Access your own private e-mail account while others cruise the web
• Share all types of files, including music, digital pictures, and documents
• Store your library of music, pictures, and files all in one place
• View your digital pictures and listen to your music anywhere in the house
• Secure your computers against Internet threats, like viruses and worms
• Enjoy multiplayer and head-to-head gaming with friends or family from any room in the house
• Enjoy gaming over the Internet with someone anywhere in the world
• Save money and time by sharing printers, scanners and other peripherals
• Share storage space and access files on another computer through your LAN (local area network) when your hard drive is full

Types of Area Network

Local Area Networks (LANs)

A data communication network that serves users in a small geographic area, usually within the same building

Wide Area Networks (WANs)

A data communication network that serves users across a broad geographical area

Campus Area Network (CAN)

A campus area network is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. It can be considered one form of a metropolitan area network, specific to an academic setting.

In the case of a university campus-based campus area network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. A campus area network is larger than a local area network but smaller than a wide area network (WAN), (in some cases)

Metropolitan Area Network (MAN)

A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities. MANs can also depend on communications channels of moderate-to-high data rates. A MAN might be owned and operated by a single organization, but it usually will be used by many individuals and organizations. MANs might also be owned and operated as public utilities. They will often provide means for internetworking of local networks. Metropolitan area networks can span up to 50km, devices used are modem and wire/cable

I reserve the right to choose whom I would want to extend these trainings to...

Different Network Devices

These devices are responsible for facilitating connection between two or more computing devices.

Ethernet Card

The system that helps connect a computer to a network is called an Ethernet card. Another name for such a card is Network Interface Card (NIC)

Internal/External Modem

Modulates outgoing digital signals from a computer or other digital device to analog signals for a conventional copper twisted pair telephone line and demodulates the incoming analog signal and converts it to a digital signal for the digital device

Hub

The term ‘hub’ is sometimes used to refer to any piece of network equipment that connects PCs together, but it actually refers to a multi-port repeater. This type of device simply passes on (repeats) all the information it receives, so that all devices connected to its ports receive that information.

Hubs repeat everything they receive and can be used to extend the network. However, this can result in a lot of unnecessary traffic being sent to all devices on the network. Hubs pass on traffic to the network regardless of the intended destination; the PCs to which the packets are sent use the address information in each packet to work out which packets are meant for them. In a small network repeating is not a problem but for a larger, more heavily used network, another piece of networking equipment (such as a switch) may be required to help reduce the amount of unnecessary traffic being generated

Switch

Switches control the flow of network traffic based on the address information in each packet. A switch learns which devices are connected to its ports (by monitoring the packets it receives), and then forwards on packets to the appropriate port only. This allows simultaneous communication across the switch, improving bandwidth.

This switching operation reduces the amount of unnecessary traffic that would have occurred if the same information had been sent from every port (as with a hub).

Switches and hubs are often used in the same network; the hubs extend the network by providing more ports, and the switches divide the network into smaller, less congested sections

Router

A device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP’s network. Routers are located at gateways, the places where two or more networks connect.

Routers use headers and forwarding tables to determine the best path for forwarding the packets, and they use protocols such as ICMP to communicate with each other and configure the best route between any two hosts.

Very little filtering of data is done through routers.

Wireless AP/Router

It is simply a router with a wireless interface which allows not only wired devices but also wireless devices to connect and communicate

Wireless Network Adapters (WNA)

A device that helps connect a computer to a network wirelessly

I reserve the right to choose whom I would want to extend these trainings to...

IP Addressing

An IP (Internet Protocol) address is a unique identifier for a node or host connection on an IP network. An IP address is a 32 bit binary number usually represented as 4 decimal values, each representing 8 bits, in the range 0 to 255 (known as octets) separated by decimal points. This is known as "dotted decimal" notation.

Every IP address consists of two parts, one identifying the network and one identifying the node for the host. The Class of the address and the subnet mask determine which part belongs to the network address and which part belongs to the node address.

IP Address Classes

Binary Equivalent (32-bit number)

128     64     32     16     8      4     2     1

                                                     1        1       1       1      1      1     1     1

           192.                    168.                      1.                     1

                                       11000000            10101000         00000001       00000001

Some first-octet values have special meanings:

• First octet 127 represents the local computer, regardless of what network it is really in. This is useful when testing internal operations.

Class A Loopback Address:          127.0.0.0

Typically all IP addresses in the range 127.0.0.0 - 127.255.255.255 are reserved for private use, but 127.0.0.1 is by convention the loopback address in almost all cases.

(Used for checking whether the TCP/IP Stack has been loaded successfully)

• First octet 224 and above are reserved for special purposes such as multicasting.

Octets 0 and 255 are not acceptable values in some situations, but 0 can be used as the second

and/or third octet (e.g. 10.2.0.100).

A class A network does not necessarily consist of 16 million machines on a single network, which would excessively burden most network technologies and their administrators. Instead, a large company is assigned a class A network, and segregates it further into smaller sub-nets using Classless Inter-Domain Routing. However, the class labels are still commonly used as broad descriptors.

Now we can see how the Class determines, by default, which part of the IP address belongs to the network (N, in blue) and which part belongs to the node/host (n, in red).

• Class A -- NNNNNNNN.nnnnnnnn.nnnnnnnn.nnnnnnnn
• Class B -- NNNNNNNN.NNNNNNNN.nnnnnnnn.nnnnnnnn
• Class C -- NNNNNNNN.NNNNNNNN.NNNNNNNN.nnnnnnnn

In the example, 192.168.1.1 is a Class C address so by default the Network part of the address (also known as the Network Address) is defined by the first two octets (192.168.1.x) and the node/host part is defined by the last octet (x.x.x.1).

In order to specify the network address for a given IP address, the node section is set to all "0"s. In our example, 192.168.1.0 specifies the network address for 192.168.1.1. When the node section is set to all "1"s, it specifies a broadcast that is sent to all hosts on the network. 192.168.1.255 specifies the example broadcast address. Note that this is true regardless of the length of the node section.

Private IP Addresses

Below are three IP network address ranges reserved for private networks. These are ranges of IP Addresses that can be used by anyone setting up internal IP networks, such as a lab or home LAN behind a NAT or proxy server or a router. It is always safe to use these because routers on the Internet by default will never forward packets coming from these addresses, in other words you may not be able to use these addresses as they are considered non-routable over the internet as they are not unique IP addresses thus you may need a unique IP called “Public IP” from your ISP to be able to do WAN (wide Area Network).

I reserve the right to choose whom I would want to extend these trainings to...

Wired VS Wireless

There are two kinds of network technologies:

• Wired - communicates through data cables (most commonly Ethernet-based)
• Wireless - communicates through radio waves

Why choose a wired network? Wired networks have been around for decades. Wired networking technology found today is known as Ethernet. The data cables, known as Ethernet network cables or wired (CAT5) cables, connect computers and other devices that make up the networks. Wired networks are best when you need to move large amounts of data at high speeds, such as professional-quality multimedia. The benefits of having a wired network include:

Why choose a wireless network? Wireless networks don't use cables for connections, but rather they use radio waves, like cordless phones. The advantage of a wireless network is the mobility and freedom from the restriction of wires or a fixed connection. The benefits of having a wireless network include:

Also known as Wi-Fi, or Wireless Fidelity, wireless networks allow you to use your network devices anywhere in an office or home, even out on the patio. You can check your e-mail or surf the Internet on your laptop anywhere in your house. There is no need to drill holes in the wall and install Ethernet cables. You can network anywhere - without wires. Outside your home, wireless networking is available in public "hotspots," such as coffee shops, businesses, hotel rooms, and airports. This is perfect for those of you who do a lot of travelling.

Linksys wireless routers are also equipped for wired connections - giving you the best of both worlds - connect wirelessly when you'd like to roam around your house, and connect wired when the utmost speed is important to you. For convenience and ease of use, wireless networking is the answer.

Mobility

• Wired devices are restricted by wires or a fixed connection
• Wireless devices have no restriction of wires or a fixed connection

Reliability

• Wired requires meticulous physical setup and planning
• Wireless provides quick, effortless installation and very easy to expand

Cost

• Wired devices are cheaper
• Wireless devices are expensive

Reliability

• Wired devices are more stable since it uses wires instead of radio signals to transmit packets
• Wireless devices are prone to interruption since it uses radio signals in transmitting packets

Performance

• Wired devices have faster transfer speed (10/100/1000 Mb/Sec)
• Wireless devices have slower transfer speed (11/54/300 Mb/Sec)

Security

• A Wired Network will require a physical connection from an attacker before they could hack in on the network
• Wireless by principle is less secured as attackers can simply hack-in even with the absence of a physical connection (still needs to be proven)

I reserve the right to choose whom I would want to extend these trainings to...

Structured Cabling

RJ45 Pin #	Wire Color (T568A)	Wire Diagram (T568A)	10Base-T Signal 100Base-TX Signal	1000Base-T Signal
1	White/Green		Transmit+	BI_DA+
2	Green		Transmit-	BI_DA-
3	White/Orange		Receive+	BI_DB+
4	Blue		Unused	BI_DC+
5	White/Blue		Unused	BI_DC-
6	Orange		Receive-	BI_DB-
7	White/Brown		Unused	BI_DD+
8	Brown		Unused	BI_DD-

RJ45 Pin #	Wire Color (T568B)	Wire Diagram (T568B)	10Base-T Signal 100Base-TX Signal	1000Base-T Signal
1	White/Orange		Transmit+	BI_DA+
2	Orange		Transmit-	BI_DA-
3	White/Green		Receive+	BI_DB+
4	Blue		Unused	BI_DC+
5	White/Blue		Unused	BI_DC-
6	Green		Receive-	BI_DB-
7	White/Brown		Unused	BI_DD+
8	Brown		Unused	BI_DD-

Crossover Cables

Another way to describe a crossover cable is that one side is wired to the T568A color code and the other side s wired to the T568B color code.

Cross Over Cable (T568B):

RJ45 Pin # (END 1)	Wire Color	Diagram End #1	RJ45 Pin # (END 2)	Wire Color	Diagram End #2
1	White/Orange		1	White/Green
2	Orange		2	Green
3	White/Green		3	White/Orange
4	Blue		4	White/Brown
5	White/Blue		5	Brown
6	Green		6	Orange
7	White/Brown		7	Blue
8	Brown		8	White/Blue

+Note: The cross over cable layout is suitable for 1000Base-T operation, all 4 pairs are crossed.

When to use a Straight through and a Crossover Cable

• Use a “crossover cable” to connect LIKE/SIMILAR devices.
• For un-like devices use a “straight through cable”.
• When you’re connecting a hub to a hub or a switch to a switch - you don't have to use crossover cables whenever the hub or switch has an UPLINK port. Simplify things by choosing devices that have UPLINK ports!!
  • When you’re connecting a hub to a hub or a switch to a switch using an uplink port, connect one end of a straight through cable to an UPLINK port and the other end of the cable to a standard port. Remember
  • You are essentially swapping the TX and RX pairs on ONE end of the cable only. This is why you connect one end of the cable to an uplink port and the other end to a standard port.
• Another thing. If you make or buy a crossover cable it will look a LOT like a straight through cable. Make sure you label a cable clearly as being a crossover cable. You can spend hours troubleshooting a problem that arises because you used the wrong kind of cable.

UPLINK Ports VS Crossover Cables

You'll notice the drawings on the previous page show ports called UPLINK ports. To understand the purpose of an UPLINK port you need to have a basic understanding of the two types of networked devices. You have NDD (Network Distribution Devices - I made that term up) and you have NU (Network Users - again, a term that I made up). An NDD will be a distribution device like a hub or switch. A NU will be a PC or a print server or a router or a broadband modem. So here is the rule of thumb:

When connecting a NDD to an NU - use a standard straight through cable.

When connecting like devices such as a hub to a hub or a PC to a PC - use a crossover cable.

A NDD (Network Distribution Device) such as a hub or a switch in intended to be connected to a NU (Network User) such as a PC. If you connect LIKE devices you have to use a crossover cable. A crossover cable is the same as a straight through cable except that the TX (Transmit) and RX (Receive) pairs are reversed or swapped on ONE end of the cable.

To a network beginner it may not always be clear when you can use a standard cable and when you need a crossover cable.  Basically you need a crossover cable when connecting LIKE devices together.

I reserve the right to choose whom I would want to extend these trainings to...

what is the difference of dual core to core 2 do or core do ? nakaklito kasi mga yun eh

Determining Network Transfer and Communication Speed Between Computers on a Network

The Transfer and Communication Speed of devices on a network is always determined by the computer with the slowest amount of connection speed

Example:

COMPUTER A

54 MB/S Connection

802.11g/Wifi G Ethernet Card

COMPUTER B

100 MB/S Connection

10/100 BaseT Ethernet Card

The Transfer and Communication Speed will be that of the computer with the lowest connection speed which is 54MB/s

Example:

COMPUTER A

54 Mbit/s Connection

802.11g/Wifi G Ethernet Card

COMPUTER B

100 Mbit/s Connection

10/100 BaseT Ethernet Card

COMPUTER C

1000 Mbit/s Connection

1GB Ethernet Card (GigaLAN)

The Transfer and Communication Speed will be that of the computer with the lowest connection speed which is 54MB/s

I reserve the right to choose whom I would want to extend these trainings to...