Networking Reading Journal

A network is two computers that can communicate and share resources.There are six main types of networks based on range which are the personal area network(PAN), local area network(LAN), metropolitan area network(MAN), wide area network(WAN), wireless LAN and Wireless WAN. These range from connections such as a phone bluetoothing with headphones to devices connected over a large geological area. Three types of networks based on how the user connects are server-based networks, workgroups and microsoft homegroups.

Server-based networks allow users to sign in to a terminal which connects them to the server that houses all of the resources and data the user could need. The server also stores information about who is allowed to access the network, what resources, such as printers, users are allowed to use and what a user can do with any resources, such as reading or writing. Server-based networks are common in businesses and tend to be more secure than workgroups as the server where the data is stored is generally stored in a locked location.

Workgroups allow each computer to act as its own server which also allows them to communicate with other devices which is known as peer-to-peer networking. Common in homes and small businesses because it is less expensive than a server-based network since it does not require a dedicated server.

Microsoft HomeGroups is like a workgroup except management of shared resources is easier as there is only one password to access all of the shared resources on the network rather than each user having to make a password for the resources they are sharing and then having to tell the other users who need access the password and having to remember any passwords they need to access other resources.

Windows offers four options when setting up a network:

• Home: Used for devices in workgroups or homegroups and allows for network discovery.
• Work: Used for devices in workgroups or homegroups and allows for network discovery.
• Public: Used for devices on a network with other unknown devices. No network discovery.
• Domain: Used for devices in a corporate environment so policies can be deployed and enforced

Networks come in many different formations called topologies, the way that the physical devices are laid out, that are made of network adapters(NICs), network media and an operating system that has enabled networking options. In a network, it is better to use a switch rather than a hub because a hub sends out the data it receives to all ports except the one it received it from which can cause collisions while a switch sends the data to the specific MAC address it was destined for, eliminating collisions.

The ethernet star topology is the most commonly used topology today and is easy to troubleshoot. If only one device can’t communicate, it is due to the device, the cable connecting the device to the switch or hub or the port the cable is plugged into. If none of the devices can communicate to each other, then the problem is the switch or hub.

Network media is how networks transmit data. The most common wired ways are through a pair of twisted copper wires and fiber optic cables. Some networks still used coax cables along with video networks. Wireless networks use air by transmitting data through radio frequencies.

Copper can be used to connect networks in two ways, twisted pair and coaxial. Furthermore, the twisted pair can be either shielded(STP) or unshielded(UTP). Computer and phone networks mainly use UTP. UTP is measured in gauges with the most common being 22-, 23-, 24- and 26-gauge. UTP also comes in categories(CAT), the most common of which are 5e, 6 and 7, which basically determines how fast the wire can transmit data. STP is used in environments such as factories where extra protection is needed to ensure the quality of the data being transmitted. Twisted pair cables can be placed in a building's air circulation system but will require special housing to ensure they are not fire hazards. The two options are plenum cable or polyvinyl chloride(PVC), with PVC being the cheaper and easier option.

Coaxial cables, or coax, are used in star and bus topologies are found mostly in video networks. Cable TV uses a coax cable but is different from network coax cables. The two connection types for coax cables are BNC connector and F connector. The two types of cable types are RG-6, which is less likely to be used with networks which works at 75-ohms and can carry frequencies up to 2200MHz while RG-59 is small, works at 75-ohms and carries frequencies up to 1000MHz.

Both coax cables and twisted pairs can be plugged into splitters but this should be avoided as this can degrade the quality of the data.

Fiber optic cables are made of glass or plastic fiber and carry light pulses. The most common use of fiber optic cables in industrial settings is being the backbone of the network by connecting inter-building networks and service provider high speed networks. Fiber optic cables often come in pairs since they can only carry signals in one direction and are mainly used in ring and star topologies. The four main types of fiber cable connectors are MT-RJ, straight tip(ST), subscriber connector(SC) and Lucent connector(LC). The two classifications of fiber optic cables are single mode which only allows one beam of light at a time or multi-mode fiber which allows for multiple beams to be sent in the same cable at the same time.

Network cables can be put in walls and ceilings but it is preferred to put them in conduits or raceways. A tone generator and probe can be used to identify cables. Cable testers check if a cable is functioning properly. Multimeter is used to take voltages, resistance and current readings. A loopback plug is used to test a port or communications ability to send and receive data.

Ethernet is the most common type of LAN. Ethernet can work at speeds of 10MB/s, 100MB/s, 1000MB/s and 10,000MB/s. Most are 10/100/1000 which means they can run at those speeds while using full duplex which means that they can send and receive data at the same time. Full duplex is used when a switch connects devices together. It uses two pairs of wires where two are used to send data and two are used to receive data which creates zero collisions. Ethernet can operate without switches, hubs or crossovers by using electrical outlets. This process is called Ethernet over Power(EoP) and sends data to EoP modules attached to power outlets and some even support wireless options. This process needs at least two EoP modules with one near the internet modem and the other connected to an outlet near where the device you want to connect is.

The International Organization for Standardization(ISO) made a model for network communication called the Open Systems Interconnect(OSI) model. The OSI model is standard for data transfer across networks. Some of the things that the OSI model dictates is how the different transmissions of media are arranged and interconnected, how and when data gets transmitted across the network and how it is known if the network data was received properly. The OSI model is a blueprint for building networks and divides networks into 7 different layers which in ascending order are physical, data link, network, transport, session , presentation and application. Each layer uses the one beneath it, excluding physical. Each layer adds information being transmitted, also known as a header. Each layer on the receiving end removes headers. Physical layer data is called bits, data link data is called frames and networking layer data is called packets.

A network protocol is a data communication language, a protocol suite is a group of protocols that work together. Transmission Control Protocol/Internet Protocol(TCP/IP) is the main protocol suite used in modern networks and is required for accessing the internet. TCP/IP contains other protocols such as File Transfer Protocol(FTP) and Hypertext Transfer Protocol(HTTP). TCP/IP only uses four layers when compared to the seven in the OSI model. The four layers in TCP/IP in ascending order are networking access, internet, transport and application.

Network adapters normally have two addresses, a MAC address and an IP address. A MAC address is a 48 bit unique number that is on a chip located on a NIC and is shown using hexadecimal and is unique for every computer on a network. The 24 bits are used to represent the manufacturer. MAC addresses are known as Layer 2 addresses, aka physical addresses.

An IP address is more organized in addressing a computer and is known as a layer 3 address in reference to the OSI model. The two types of IP addresses are IPv4 and IPv6. IPv4 is most commonly used on Lans and is a 32 bit number that is put into a NIC’s configuration parameters. This is the address used across networks and when on the internet. IPv6 is 128 bits long, is shown in hexadecimal and is more common on corporate devices and with specific ISPs. Modern computers have both IPv4 and IPv6 addresses. Ipv4 has five classes, A-E, with A-C being network devices, D used for multicasting and E being used for experimentation. Class A has the first number between 0 and 127, B has 128-191 and C has 192-223. There are also private and public IP addresses where private IP addresses are not able to be transmitted across the internet.

An IP address is broken into two parts, the network number and the host number. The network number is used to represent the network the device is on while the host address represents the specific device on the network. The number of bits used to represent the two parts change with the class of IP addresses being used.

A subnet mask is a number that is used to determine which part of the IP address is the network and which part is the host. The mask does not always have to match the classes, there are classless inter-domain routing(CIDR) subnet masks. CIDR is a method of allocating IP addresses based on the amount of host addresses required for a network.

Wireless networks transmit data through the air either using infrared, which is 1-400 THz, or radio frequencies in the 2.4GHz or 5GHz range. Most home and business networks use radio frequencies Wireless networks work at the first and second layer of the OSI model.

Bluetooth is a wireless technology used for PANs and operates in the range of 2.4GHz with three classes of devices labeled 1-3. The class is determined by the range with class one having a range of less than 30 feet, class two having a range of 33 feet and class three having a range of 328 feet and all have a maximum transfer rate of 24Mb/s. Bluetooth can be used to send both data and voice, eight devices can be connected to a PAN via bluetooth and bluetooth has integrated 128 bit encryption.

The most common parts of a wireless network are wireless NICs, an access point, a wireless bridge and a wireless router. Some of the main types of wireless NICs are integrated ports, ExpressCard, USB, PCI and PCIe. The wireless access point(AP) is a device used to send and receive data from devices that have wireless NICs. In corporate environments, APs are commonly powered by Ethernet cables using Power over Ethernet(PoE). If a switch does not support PoE, a PoE injector can be used to power the AP through ethernet.

Two ways a wireless network can be designed is infrastructure mode, where devices connect to the AP and share bandwidth or ad hoc mode where devices talk directly to each other without going through the AP. APs can handle 30 to 200 wireless devices based on the manufacturer, network environment, usage and type of data transmitted.

Each AP is assigned a service set identifier (SSID) which can be changed and is composed of 32 alphanumeric characters that differentiate between wireless networks. The SSID is broadcasted by the AP by default which allows it to be found on wireless network lists. APs can also be connected to another AP and wireless repeaters/extenders through both wired and wireless connections while connecting to a wired network requires cabling in. Two APs connected to two different networks have two different SSIDs while two APs connected to the same network share the SSID. APs can also be configured to have a password and a channel ID, but it is important to ensure that the username and password is changed from the default option as those are available online. The channel ID is used to dictate what frequency the AP uses with up 14 channels being available to 2.4GHz APs in certain spots of the world. It is important that APs have channels at least five channel numbers apart from other APs to prevent interference and that devices connected to an AP share that AP’s frequency. The three most commonly used channel IDs are 1,6 and 11.

APs and wireless cards have either external or built-in antennas which are used to send and receive radio waves. Wireless NICs and APs can also have detachable antennas. External antennas allow the user to adjust them to get a better signal while built-in antennas require the device to be adjusted, such as with laptops, to receive better signal. The two main types of antennas are omnidirectional and directional. Omnidirectional antennas send out radio waves in all directions. Integrated wireless NICs use omnidirectional antennas. Directional antennas send waves in a specific direction and are commonly used to connect two buildings to one another and to limit the connectivity outside of buildings. Each antenna has a specific radiation pattern, also known as a propagation pattern which determines what direction(s) radio waves are sent and received. The data lost as it is transmitted from an antenna through the air is called attenuation, also called path loss. Attenuation is measured in decibels which measures the ratio between the two signal levels. Attenuation is affected by distance between the transmitter and the receiver, obstructions and height of the transmitter. Interference from other devices that use radiation also affects attenuation.

Antenna power level is also known as antenna gain which is measured in dBi. Sometimes antennas are measured in dbD, 0dBd = 2.14 dBi. More gain means more coverage in a particular direction. Differently shaped antennas transmit in different patterns.

A site survey is a test to determine the best placement of hardware to get the most coverage. It involved temporarily mounting an AP and then walking around with a device with a wireless NIC and site survey software to determine how strong the connection is.

Wi-Fi analyzers and wireless locators can be used to determine if there is a wireless network or hot spot in an area. Wireless devices attached to people, pets or things can be located using Wi-Fi analyzers or wireless locators.

The four most common types of antennas are parabolic, Yagi, patch and dipole. Parabolic antennas are either grids or dishes, are used outside and provide the greatest distance for wireless networks. Both Yagi and patch antennas are used for long distance communication and can be placed indoors or outdoors.

Multiple input/multiple output(MIMO) antennas use multiple 2.4GHz and 5GHz antennas. MIMO antennas can be either external or built into wireless devices and having multiple antennas allow for faster speeds.

A dipole antenna attaches to wireless NICs and APs and is used indoors and has the lowest range of all the mentioned antennas.

The IEEE 802.11 are committees that define wireless network standards. 802.11 based wireless networks use Carrier Sense MUltiple Access/Collision Avoidance(CSMA/CA) as an access method. With CSMA/CA network devices listen to cables for traffic and when they want to transmit, they put out a jam signal and then wait a specific amount of time for all the other devices to hear the signal before they transmit and if they run into a collision they stop transmitting and wait a set amount of time until attempting to transmit again.

When a NIC is installed into a computer, it can take four or more steps to configure the NIC before being able to access the network. The first step is to determine that an appropriate slot, port or integrated wireless NIC is available, then, optionally, all of the appropriate NIC drivers can be installed. The next step is to name the computer something unique and join a workgroup or domain if desired. The final step is to configure the TCP/IP. The TCP/IP is configured, an IP address and a subnet mask must be assigned to the network device. The two ways to do this are either to statically define the IP address and mask, which means manually entering the IP address and mask, or dynamically obtain the address using DHCP. Dynamic host configuration protocol(DHCP) is used to assign IP addresses to network devices. A DHCP server contains a pool of viable IP addresses.

APIPA is automatic private IP addressing and is used when the DHCP is not available. This allows computers to connect to each other but not the internet. Another way around a downed DHCP is an alternative configuration but can also be used on a laptop that travels between a place that uses DHCP and a second location that uses statically assigned IP addresses.

A default gateway is an IP address that is assigned to a network device that directs where the device sends packets going to remote networks. The gateway’s IP address is the same as the router of the network it is connected to.

A DNS is an app that runs on network servers that translate internet names to IP addresses. A DNS can be configured for one or multiple DNS servers using DHCP. If a DNS does not know a domain name, it can contact another DNS to request the information. Wired and wireless adapters require IP addresses, default gateways and DNS configuration.

The latest drivers for windows should be downloaded before a wireless NIC is installed. After installation, SSID and security options are available to be entered.

In order for a virtual machine to have a virtual NIC the real machine must have a physical NIC installed. Virtual NICs have their own MAC address and can have their own IP addresses. The virtual NIC can use the physical NIC to connect to the internet and if the virtual machine is having trouble connecting to the internet then the virtual NIC should be verified.

Wireless APs with the ability to route are designed for small office/home office(SOHO) environments. These APs often have network functions such as DMZ, QoS and a DHCP server.

The first step in troubleshooting a network is determining how many devices are affected. If a network port is suspected to be the source of the problem, try a different cable or a loopback plug. The ping command is one of the best ways to determine the amount of devices that are having problems. Pinging devices on the same network is a good way of checking local connectivity. If a website can be pinged using the IP address but not the name, there is a problem with the DNS server. Using the ipconfig command in the windows cmd allows the user to see the IP configuration on a windows computer. The tracert command shows the path a packet took through a network. This allows the user to see network faults and latency. Nslookup allows the user to see domain names and their IP addresses. The net command allows a user to control almost everything on a network from the command terminal. Netdom enables the user to manage workstations within a domain.

An embedded system is a computer that has a specific job with a larger system. These systems contain components similar to regular desktops such as processor, RAM and ports. A legacy system is an outdated computer system or networking equipment that needs to be replaced or updated but is kept around because it is not cost effective to replace, is used with a specific irreplaceable system or provides a function that would no longer be needed in the near future.

Common acronyms, address resolution protocol(ARP), Code Division Multiple Access(CDMA), Common Internet File System(CIFS), Fiber Distributed Data Interface(FDDI), Global System for Mobile Communication(GSM), Hypertext Markup Language(HTML), Internet Control Message Protocol(ICMP), Lightweight Directory Access Protocol(LDAP), Network Address Translation/Port Address Translation(NAT/PAT), Point of Presence(POP), Simple Network Management Protocol(SNMP), Secure Sockets Layer(SSL), Transmission Control Protocol(TCP), User Datagram Protocol(UDP) and Voice over IP(VoIP).

The network and sharing center control panel is where most of the network configuration is done.

A connection protocol used with dial up networking is Point-To-Point Protocol(PPP).

Cloud technology is the behavior of having resources that are not on site. The four ways cloud services can be deployed are private, public, hybrid and community. A private cloud is owned by a company and contains their network infrastructure off site and is responsible for the upkeep of the software and hardware. A public cloud operated by a cloud provider and sells cloud services of different sizes to different sized businesses, this model requires the vendor to upkeep the software and hardware. A hybrid cloud is a combined private and public cloud. In this model, a company would have the stuff as with a private cloud but in the event of an emergency, would have access to the public cloud. A community cloud is when multiplier users have access to the same resource stored in the cloud.