Web kiloseven.blogspot.com
www.arrl.org www.eham.net

2012-05-31

A+: More on TCP/IP Configuration

TCP/IP Alternate Configuration


The Alternate Configuration tab is used to set up a different configuration for use when a DHCP server is not available or when a different set of user-configured settings are needed, as when a laptop is being used at a secondary location. By default, automatic private IP addressing (APIPA) is used when no DHCP server is in use. APIPA assigns each system a unique IP address in the 169.254.x.x range. APIPA enables a network to perform LAN connections when the DHCP server is not available, but systems using APIPA cannot connect to the Internet.  When you see a 169.254 series address, DHCP has failed, and should be repaired.

You can also use the Alternate Configuration tab to specify the IP address, subnet mask, default gateway, DNS servers, and WINS servers. This option is useful if this system is moved to another network that uses different IP addresses for these servers.


TCP/IP User-Configured IP and DNS Addresses

When a DHCP server is not used, the General tab is used to set up the IP address, subnet mask, default gateway, and DNS servers used by the network client .

TCP/IP User-Configured Advanced Settings

Click the Advanced button to bring up a multitabbed dialog for adding or editing gateways (IP Settings), DNS server addresses (DNS), adjusting WINS resolution (WINS), and adjusting TCP/IP port filtering (Options). These options can be used whether DHCP addressing is enabled or not.

Understanding IP Addressing, Subnet Masks, and IP Classes

An IPv4 address consists of a group of four numbers that each range from 0 to 255, for example: 192.168.1.1. IP addresses are divided into two sections: the network portion, which is the number of the network the computer is on, and the host portion, which is the individual number of the computer. Using the IP address we just mentioned as an example, the 192.168.1 portion would typically be the network number, and .1 would be the host number. A subnet mask is used to distinguish between the network portion of the IP address, and the host portion. For example, a typical subnet mask for the IP address we just used would be 255.255.255.0. The 255s correspond to the network portion of the IP address.

The subnet mask is also used to define subnetworks, if subnetworking is being implemented. Subnetworking goes beyond the scope of the A+ exam.

Both computers and other networked devices, such as routers and network printers, can have IP addresses, and some devices can have more than one IP address. For example, a router will typically have two IP addresses—one to connect the router to a LAN, and the other that connects it to the Internet, enabling it to route traffic from the LAN to the Internet and back.

IP addresses are divided into three major categories: Class A, Class B, and Class C, which define ranges of IP addresses. Class A is designated for large corporations, ISPs, and government. Class B is designated for mid-sized corporations and ISPs. Class C is designated for small offices and home offices.

Class Mask (default) IP range
A 255.0.0.0 0.0.0.0 - 127.255.255.255
B 255.255.0.0 128.0.0.0 - 191.255.255.255
C 255.255.255.0 192.0.0.0 - 223.255.255.255

The 127 network is reserved for testing. This is known as the loopback, for example 127.0.0.1. The usable starting IP for Class A is actually 1.0.0.0.

In any given network the first and last addresses are reserved and cannot be assigned to computers or other hosts. For example, in the 192.168.1.0 network, 192.168.1.1 through 192.168.1.254 can be assigned, but 192.168.1.0 is reserved for the network number, and 192.168.1.255 is reserved for something called the broadcast.

Each number in an IP address is called an octet. An octet is an 8-bit byte. This means that in the binary numbering system the number can range from 00000000—11111111. For example, 255 is actually 11111111 when converted to the binary numbering system. Another example: 192 equals 11000000.

To convert numbers from decimal to binary and vice-versa use the Windows calculator. Press Windows+R to bring up the Run prompt, then type calc. This will run the Windows Calculator. From here click View on the menu bar and select Scientific. Now you will notice radio buttons on the upper left that allow you to change between numbering systems. Simply type any number, and then select the numbering system you want to convert it to.

In a Class A network, the first octet is the network portion of the IP address, and the three remaining octets identify the host portion of the IP address. Class B networks use the first and second octets as the network portion, and the third and fourth octets as the host portion. Class C networks use the first three octets as network portion and the last octet as the host portion of the IP address.

The size of the network portion increases in octets, and the host portion decreases as you ascend through the classes. As time goes on, you will see more patterns like this within TCP/IP.

Labels:

2012-05-30

A+: Installing Network Protocols

Before a network connection can function, it must be properly configured. Here;s some terminology you'll need:


The IP address identifies a computer or device on the network and must be unique. To make sure it is unique, it can be auto-assigned by a DHCP server.

The DNS configuration identifies the DNS (Domain Naming System) and speficies one or more DNS servers. It is the 'White Pages' of the Internet, providing the IP address when requested for any web address, host name or domain name.

A Gateway here is a logical device (the term is also used for a hardware device) which identifies the IP address of a device which connects a computer or network to the Internet or another network. It is the same address for all computers and devices on the same network.

The WINS configuration maps IP addresses to NetBIOS computer names, and was used with NT4 and earlier versions of Windows. It is obsolete.


Installing Network Protocols in Windows

Depending upon the network protocol you want to install and the version of Windows in use on a particular computer, you can install any of several different protocols through the normal Windows network dialogs. However, NetBEUI is an older, non-routing protocol which does not work with Vista or 7 and which is not included with XP (you can make it work using KB 301041, installing it from the XP install CD folder Valueadd\MSFTNet\NetBEUI ). You may see it in Windows 2000.

Windows supports TCP/IPv4 and TCP/IPv6. TCP/IPv4 is still the most commonly used version. If TCP/IP is referred to without a version, it generally means TCP/IPv4.

To install a network protocol in Windows Vista or XP/2000, follow this procedure:

    Step 1. Open the Network Connections window

    • In Windows Vista/7, click Start, Control Panel, and then double-click the Network and Sharing Center icon. Next, click Manage Network Connections under tasks.

    • In Windows XP/2000, click Start, Control Panel, and then double-click the Network Connections (called Network in 2000) icon in Control Panel or right-click My Network Places and select Properties.

    Step 2. Right-click the connection you want to modify and select Properties.
    Step 3. Click the Install button.
    Step 4. Click Protocol.
    Step 5. Select the protocol you want to add.
    Step 6. Click OK.

After the protocol is installed, select the protocol and click Properties to adjust its properties setting.

TCP/IPv4 Configuration

The TCP/IPv4 protocol, although it was originally used for Internet connectivity, is now the most important network protocol for LAN as well as larger networks. To connect with the rest of a TCP/IP-based network, each computer or other device must have a unique IP address. If the network connects with the Internet, additional settings are required.

There are two ways to configure a computer’s TCP/IP settings, with a Server-assigned IP address (via DHCP) or a Static IP address.

All versions of Windows default to using a server-assigned IP address and this is the preferable method for configuring a TCP/IP network. Use a manually assigned IP address if a Dynamic Host Configuration Protocol (DHCP) server (which provides IP addresses automatically) is not available on the network—or if you need to configure a firewall or router to provide different levels of access to some systems and you must specify those systems’ IP addresses. Routers, wireless gateways, and computers that host an Internet connection shared with Windows’s Internet Connection Sharing or a third-party sharing program all provide DHCP services to other computers on the network.

To configure TCP/IP in Windows, access the Internet Protocol Properties window; this window contains several dialogs used to make changes to TCP/IP. Note that these dialogs are nearly identical in Windows XP and Windows Vista. To open the General tab of the Internet Protocol Properties window, open Network Connections, right-click the network connection, select Properties, click Internet Protocol (TCP/IP) in the list of protocols and features, and click Properties.


To determine the IP address, default gateway, and DNS servers used by a system using DHCP addressing, open a command prompt and enter the ipconfig /all command.


Labels:

2012-05-29

A+: Switches and Hubs for LANs, Repeaters, Bridges, and Routers for WANs

Hubs connect different computers with each other on an Ethernet network based on UTP or STP cabling. A hub has several connectors for RJ45 cabling, a power source, and signal lights to indicate network activity. Most hubs are stackable, meaning that if you need more ports than the hub contains, you can connect it to another hub to expand its capabilities.

A hub is the slowest connection device on a network because it splits the bandwidth of the connection among all the computers connected to it. For example, a five-port 10/100 Ethernet hub divides the 100 Mbps speed of Fast Ethernet among the five ports, providing only 20 Mbps of bandwidth to each port for Fast Ethernet and 10/100 adapters, and only 2 Mbps per port for 10BASE-T adapters. A hub also broadcasts data to all computers connected to it.

A switch resembles a hub but creates a dedicated full-speed connection between the two computers that are communicating with each other. A five-port 10/100 switch, for example, provides the full 10 Mbps bandwidth to each port connected to a 10BASE-T card and a full 100 Mbps bandwidth to each port connected to a Fast Ethernet or 10/100 card. If the network adapters are configured to run in full-duplex mode and the switch supports full-duplex (most modern switches do), the Fast Ethernet bandwidth on the network is doubled to 200 Mbps, and the 10BASE-T bandwidth is doubled to 20 Mbps. Switches can be daisy-chained in a manner similar to stackable hubs, and there is no limit to the number of switches possible in a network. However, switches introduce delays in the network, or latency, as it takes time to compute where the packets should go.

Beyond LANs— WANs

Windows since XP features built-in bridging capabilities. You can also use a wireless router with a built-in switch to create a single network with both wired and wireless clients.

Hubs and switches are the only connectivity equipment needed for a workgroup LAN. However, if the network needs to span longer distances than those supported by the network cabling in use or needs to connect to another network, additional connectivity equipment is needed.

• Repeater—A repeater boosts signal strength to enable longer cable runs than those permitted by the “official” cabling limits of Ethernet. Hubs and switches can be used as repeaters.

• Router—A router is used to interconnect a LAN to other networks; the name suggests the device’s similarity to an efficient travel agent, who helps a group reach its destination as quickly as possible. Routers can connect different types of networks and protocols to each other (Ethernet, token ring, TCP/IP, and so on) and are a vital part of the Internet. Router features and prices vary according to the network types and protocols supported. Modern home routers also include switches and Wi-Fi access.

Labels:

2012-05-28

A+: Wireless Ethernet (WLAN) Configuration

Most home and small-business networks using encryption will use a pre-shared key (PSK). When a pre-shared key is used, both the wireless router or access point and all clients must have the same PSK before they can connect with each other. WPA and WPA2 also support the use of a RADIUS authentication server, which is used on corporate networks.

Wireless Ethernet requires additional configuration compared to wired Ethernet, as shown below:

The SSID (Service Set Identifier) names the network. XP and later can detect SSIDs on unsecured ('open') networks.

The Channel specifies a predefined frequency for all stations to use. Since the Wireless Zero Configuration service of XP, WIndows will determine the channel to use automatically, but if ad-hoc (peer-to-peer) configurations are used or if vendors software is used for configuration, a manual assignment may be needed. Only channels 1, 5, 11 and 14 do not overlap with other channels, and channel 14 can't be used in North America.

WEP (Wireless Equivalent Privacy) is the oldest wireless security method, and was intended to prevent access by unauthorized users. 802.11n does not permit WEP, and you should use WPA2 or WPA if available to all devices on the WLAN. If WEP, WPA or WPA2 is not used or is disabled (which is the default when shipped), anyone can get on the WLAN and record the network traffic if they know or can find the SSID, and SSID-finding software is easily obtained.  Also, WEP is an inefficient protocol, and can take up to 35% of your  router's CPU time, whereas WPA and WPA2 are not only more secure, but also more efficient, limiting CPU time to 5%.

WEP Encryption Strength can be set to 64-bit (13 ASCII characters) or 128-bit (26 ASCII characters). You should not use WEP if you can use WPA or WPA2, and you should not use 64-bit WEP if you can use 128-bit WEP, but, really, if an FBI agent can break 128-bit WEP in 5 minutes in his first attempt (at a Las Vegas hacker's convention years ago), imagine how quickly your hacking-obsessed 14-year-old neighbor can break 128-bit WEP.  Make sure to use WPA or WPA2. 

The WEP Key is the password for the encryption of your network for security. All network devices must use the same method and the same key.


WPA is Wi-Fi Protected Access, a stronger and faster security method than WEP. A driver or firmare upgrade may be needed for older equipment which did not originally support WPA.  WPA2 is a newer, 21-Century variation which is stronger than WPA.


The WPA Encryption Type for WPA or WPA2 can be either

  • TKIP, the Temportal Key Integrity Protocol, a 128-bit protocol which is compatible with older gear, or
  • AES, the Advanced Encryption Standard, aka CCMP, a preferred protocol using 128-bits or 256-bits which is also used elsewhere. 
WPA Keys may be up to 63 characters long, and can include uppercase and lowercase letters as well as numbers and other characters. Some hardware may not support 63 character keys.

WPS is Wireless Protected Setup, a newer method for automated security. It, too, should be avoided, as it's been broken. See http://en.wikipedia.org/wiki/Wi-Fi_Protected_Access for more.



Labels:

2012-05-27

A+: Installing Network Interface Cards

Although many recent computers include a 10/100 or 10/100/1000 Ethernet port or a Wireless Ethernet (WLAN) adapter, you often need to install a network interface card (NIC) into a computer you want to add to a network.

PCI, PCI Express


To install a Plug and Play (PnP) network card, follow this procedure:


  • Turn off the computer and remove the case cover.
  • Locate an available expansion slot matching the network card’s design (most use PCI, but some servers and workstations might use PCI-X or PCI Express).
  • Remove the slot cover and insert the card into the slot. Secure the card in the slot.
  • Restart the system and provide the driver disk or CD-ROM when requested by the system.
  • Insert the operating system disc if requested to install network drivers and clients.
  • The IRQ, I/O port address, and memory address required by the card will be assigned automatically.
  • Test for connectivity (check LED lights, use a command such as ping, and so on), then close the computer case.


USB


Although USB network adapters are also PnP devices, you normally need to install the drivers provided with the USB network adapter before you attach the adapter to your computer. After the driver software is installed, the device will be recognized as soon as you plug it into a working USB port.

Most USB network adapters are bus powered. For best results, they should be attached to a USB port built into your computer or to a self-powered hub. Some adapters support USB 2.0, which provides full-speed support for 100BASE-T (Fast Ethernet) signal speeds.

If you are using a wireless USB adapter, you can improve signal strength by using an extension cable between the adapter and the USB port on the computer. Using an extension cable enables you to move the adapter as needed to pick up a stronger signal.  Standard USB extension cables can reach up to 5 meters(16') without an intervening powered hub.


PC Card/CardBus

PC Card network adapters work with both the original 16-bit PC Card slot and the newer 32-bit CardBus slot. However, CardBus cards work only in CardBus slots.   Both PC Card and CardBus cards are detected and installed by built-in support for these adapters in Windows 2000 and newer versions.  Some PC Card and CardBus network adapters often require that a dongle be attached to the card to enable the card to plug into a network port.


Configuring Network Interface Cards

Although PCI, USB, PC Card, and CardBus network adapters as well as integrated adapters support PnP configuration for hardware resources, you might also need to configure the network adapter for the type of media it uses, for the speed of the connection and, with Wireless Ethernet adapters, the security settings that are used on the wireless network.


Hardware Resources

Typical network interface card hardware resource settings include IRQ and I/O port address range.  If the workstation is a diskless workstation, a free upper memory address must also be supplied for the boot ROM on the card. A few older network cards also use upper memory blocks for RAM buffers; check the card’s documentation.


Media Type

Most recent Ethernet cards are designed to use only UTP Category 3 or greater network cabling. However, some older cards were also designed to use 10BASE5 (Thicknet) or 10BASE2 (Thinnet) cabling. Cards that are designed to use two or more different types of cabling are known as combo cards, and during card configuration, you need to select the type of media that will be used with the card. This option is also known as the Transceiver Type option. Depending upon the card’s drivers, you might need to make this setting through the card’s command-line configuration program or the card’s properties sheet in Windows Device Manager.

Some network adapters designed for use with UTP cable can automatically sense when the cable is not connected. Windows XP might display an icon in the system area to indicate when a cable is not connected to a network adapter. To enable notification, open the Network Connections window, right-click the connection, select Properties, and make sure the option Show Icon in Notification Area When Connected is enabled.

Full/Half-Duplex


If the hardware in use on an Ethernet, Fast Ethernet, or Gigabit Ethernet network permits, you can configure the network to run in full-duplex mode. Full-duplex mode enables the adapter to send and receive data at the same time, which doubles network speed over the default half-duplex mode (where the card sends and receives in separate operations). Thus, a 10BASE-T-based network runs at 20 Mbps in full-duplex mode; a 100BASE-T-based network runs at 200 Mbps in full-duplex mode; and a 1000BASE-T-based network runs at 2,000 Mbps in full-duplex mode.

To achieve full-duplex performance on a UTP-based Ethernet network, the network adapters on a network must all support full-duplex mode, be configured to use full-duplex mode with the device’s setup program or properties sheet, and a switch must be used in place of a hub.

Labels:

2012-05-26

A+: Connector Types

Most coaxial cables, including RG-58, RG-59, and RG-6 use a BNC (Bayonet Neill-Concelman) connector. RG-58 uses a T-adapter to connect to a 10BASE2 Ethernet adapter. RG-11 (Thicknet) cable is connected to an Ethernet card by means of an external transceiver, which attaches to the AUI port on the rear of older Ethernet network cards. The transceiver attaches to the cable with a so-called “vampire tap.”

10BASE-T, 100BASE-T, and 1000BASE-T Ethernet cards using copper wire all use the RJ45 connector, as do newer token-ring, some ISDN and most cable Internet devices. DSL devices often use the RJ11 connector, as do dial-up modems.

To attach a cable using RJ11 or RJ45 connectors to a network card or other device, plug it into the connector so that the plastic locking clip snaps into place; the cable and connector will fit together only one way. To remove the cable, squeeze the locking clip toward the connector and pull the connector out of the jack. Some cables use a snagless connector; squeeze the guard over the locking clip to open the clip to remove the cable.

Fiber-optic devices and cables use one of several connector types. The most common include

    • SC— Uses square connectors
    • ST— Uses round connectors
    • FC— Uses a round connector

If you need to interconnect devices which use two different connector types, use adapter cables which are designed to match the connector types and other characteristics of the cable and device. Making these cables is generally a waste of time, and the quality is generally lower than factory-built cable.

Labels:

2012-05-25

A+: Fiber Optic and Coax Cables

Fiber-optic cabling transmits signals with light rather than with electrical signals, which makes it immune to electrical interference. It is used primarily as a backbone between networks.

When Ethernet is run over fiber-optic cables, the letter F is used in place of T (twisted pair) in the name. For example, 10BASE-F is 10 Mbps Ethernet running on fiber-optic cable, 100BASE-F is 100 Mbps Ethernet running on fiber-optic cable, and so on.

Fiber-optic cable comes in two major types:

    • Single-mode— Has a thin core (between 8 and 10 microns) designed to carry a single light ray long distances.

    • Multi-mode— Has a thicker core (62.5 microns) than single-mode; carries multiple light rays for short distances.

Fiber-optic cabling can be purchased prebuilt, but if you need a custom length, it should be built and installed by experienced cable installers because of the expense and risk of damage. Some network adapters built for servers are designed to use fiber-optic cable. Otherwise, media converters are used to interconnect fiber optic to conventional cables on networks.

Coaxial cables ('Coax')



Coaxial cabling is the oldest type of network cabling; its data wires are surrounded by a wire mesh for insulation. Coaxial cables, which resemble cable TV connections, are not popular for network use today because they must be run from one station directly to another rather than to or from a hub/switch.
Coaxial cabling creates a bus topology; each end of the bus must be terminated, and if any part of the bus fails, the entire network fails.

The oldest Ethernet standard, 10BASE5, uses a very thick coaxial cable (RG-8) that is attached to a NIC through a transceiver that uses a so-called “vampire tap” to connect the transceiver to the cable. This type of coaxial cable is also referred to as Thick Ethernet or Thicknet.

Thin Ethernet, also referred to as Thinnet, Cheapernet, or 10BASE2 Ethernet was used for low-cost Ethernet networks before the advent of UTP cable. The coaxial cable used with 10BASE2 is referred to as RG-58. This type of coaxial cable connects to network cards through a T-connector that bayonet-mounts to the rear of the network card using a BNC connector. The arms of the T are used to connect two cables, each running to another computer in the network.

If the workstation is at the end of a network, a terminating resistor is connected to one arm of the T to indicate the end of the network. If a resistor is removed, the network fails; if a station on the network fails, the network fails.

Two other types of coaxial cable are common in cable Internet, satellite Internet, and fixed wireless Internet installations:
RG-59— Used in older cable TV or satellite TV installations; 75-ohm resistance. Also used by the long-obsolete Arcnet LAN standard.
RG-6— Uses same connectors as RG-59, but has a larger diameter with superior shielding; used in cable TV/Internet, satellite TV/Internet, and fixed wireless Internet/TV service; 75-ohm resistance.


Labels:

2012-05-24

A+: Cable and Connector Types

Network cards are designed to interface with one or more types of network cables. UTP and STP cable can be purchased in prebuilt assemblies or can be built from bulk cable and connectors. Four major types of network cables are:

    • Unshielded twisted pair (UTP)
    • Shielded twisted pair (STP)
    • Fiber-optic
    • Coaxial (rare now)

USB, serial (RS-232) null modem and parallel (LPT) crossover cables can be used with direct parallel or direct serial connections (also known as direct cable connection), which are special types of two-station networking included in Windows that use standard network protocols but do not use network cards. Infrared (IR) ports built into many notebook computers can also be used with direct serial connection.

Unshielded twisted pair (UTP) cabling is the most common of the major cabling types. The name refers to its physical construction: four twisted pairs of wire surrounded by a flexible jacket.   It comes in various grades, of which Category 5e is the most common of the standard cabling grades. Category 5e cabling is suitable for use with both standard 10BaseT and Fast Ethernet networking, and can also be used for Gigabit Ethernet networks if it passes compliance testing.

Shielded twisted pair (STP) cabling was originally available only in Category 4, which was used by the now largely outdated IBM Token-Ring Networks. STP uses the same RJ-45 connector as UTP, but includes a metal shield for electrical insulation between the wire pairs and the outer jacket. It’s stiffer and more durable, but also more expensive and harder to loop through tight spaces than UTP. Type 1 STP cable used by older token-ring adapters has a 9-pin connector. STP cabling is also available in Category 5, 5e, and 6 for use with Ethernet networks. It is used where electromagnetic interference (EMI) prevents the use of UTP cable.

The connector used by Ethernet cards that use UTP or STP cable is commonly known as an RJ45 connector. RJ stands for registered jack; the RJ45 has 8 contacts that accept 8 wires, also known as pins. It resembles a larger version of the RJ11 connector used for telephone cabling. UTP cabling runs between a computer on the network and a hub or switch carrying signals between the two. The hub or switch then sends signals to other computers (servers or workstations) on the network. When a computer is connected to a hub or switch, a straight through cable is used. This means that both ends of the cable are wired the same way. If a computer needs to be connected directly to another computer, a crossover cable, which has a different pin configuration on one end, is used. Keep in mind that between the computer and the hub or switch, there might be other wiring equipment involved, for example RJ45 jacks, patch panels, and so on. UTP and STP cable can be purchased in prebuilt form or as bulk cable with connectors, so you can build the cable to the length you need. 

Although RJ45 is the common name for the UTP Ethernet connector, this is a misnomer, the proper name is 8P8C (8 position, 8 contact). Don’t confuse it with the RJ45S connector, an eight-position connector, used for telephone rather than computer data. An RJ45S jack has a slightly different shape than the connector used for Ethernet, and includes a cutout on one side to prevent unkeyed connectors from being inserted into the jack.     To see drawings of the RJ45S jack and other telephone jacks, see http://www.siemon.com/us/standards/13-24_modular_wiring_reference.asp  .

A chart of wired cable categories follows below:


Category Type+ Speed LANs
'CAT' pairs (Mbps) using
--- --- --- ---
1 UTP 1 varies phone, DSL, HomePNA (up to 100Mbps)
2 UTP 1 4 max LocalTalk (Apple, obsolete)
3 UTP 4 10 max 10Base-T (repl w/ CAT5, CAT5e, CAT6)
4 STP 1 16 max Token ring (obsolete)
5 U/STP 4 1000 max 10Base-T, 100Base-T, 1000Base-T
5e U/STP 4 1000 max 10Base-T, 100Base-T, 1000Base-T enhanced CAT5
6 U/STP 4 1000 max 10Base-T, 100Base-T, 1000Base-T higher freqs than CAT5, CAT5e
7 U/STP 4 1000 max 10Base-T, 100Base-T, 1000Base-T uses 12 connector GG45 connector (backwards compatible w/ RJ45)

The outer jacket of UTP, STP, and coaxial cable is usually made of PVC (polyvinyl chloride), a low-cost durable vinyl compound. Unfortunately, PVC creates dense poisonous smoke when burned. If you need to run network cable through suspended ceiling or air vents, you should use more-expensive plenum cable, which produces less smoke and a lower level of toxic chemicals when burned.

Labels:

2012-05-23

A+: Wireless LAN compatibility chart

Ethernet Radio Throughput Compatibility
Type Frequency (Theoretical) Notes
--- ---          ---         ---
802.11a 5 GHz 54 Mbps Req dual-mode hw (a/b or a/g) 802.11n supports 5GHz
802.11b 2.4 GHz 11 Mbps 802.11g
802.11g 2.4 GHz 54 Mbps 802.11b, 802.11n
802.11n 2.4 GHz (std) 600 Mbps max 802.11b, 802.11g (802.11a on WLANs also supporting 5GHz)
5 Ghz (opt) (300 Mbps typ max)

Labels:

2012-05-22

A+: Other popular protocols

Bluetooth: Bluetooth is a short-range low-speed wireless network primarily designed to operate in peer-to-peer mode (known as ad-hoc) between PCs and other devices such as printers, projectors, smart phones, mice, keyboards, and other devices. Bluetooth runs in the same 2.4GHz frequency used by IEEE 802.11b, g, and n wireless networks, but uses a spread-spectrum frequency-hopping signaling method to help minimize interference. Bluetooth devices connect to each other to form a personal area network (PAN).

Some systems and devices include integrated Bluetooth adapters, and others need a Bluetooth module connected to the USB port to enable Bluetooth networking.

Infrared:  Infrared is a short-range, low-speed, line-of-sight network method that can be used to connect to other PCs, PDAs, or Internet kiosks. Infrared networking is based on the Infrared Data Association (IrDA) protocol. Some laptops include an integrated IrDA port. IrDA can also be used for printing to printers that include an IrDA port or are connected to an IrDA adapter.

If you want to use a computer that does not have IrDA support with infrared networking, you can add an IrDA adapter. Many desktop motherboards include integrated IrDA support. To enable IrDA support, connect a header cable (available from various third-party sources) to the IrDA port and configure the system BIOS to provide IrDA support. On many systems with integrated IrDA support, one of the COM ports can be switched between its normal mode and IrDA support.

To add IrDA support to computers that don’t include an IrDA port, use a third-party IrDA module that connects to the USB port.

Cellular:  Digital cellular phone networks can be used for Internet access and remote networking, a feature that is extremely useful to mobile workers. To enable a laptop to use a cellular network for data access, you need to connect a cellular modem to your PC and purchase the appropriate data access plan from a wireless carrier.  Cellular modems can be connected to USB ports or installed into CardBus or ExpressCard slots. They can be purchased separately or as a bundle with a data access plan. If you purchase a cellular modem separately, make sure it supports the data access method used by your wireless carrier.


VoIP: Voice over IP (VoIP) is an increasingly popular method for providing home and business telephone access. VoIP routes telephone calls over the same TCP/IP network used for LAN and Internet access. Companies such as Vonage, Skype, AT&T, Verizon, and others provide VoIP services.

To add VoIP service to an existing Ethernet network, you can use either an analog telephone adapter (ATA) or a VoIP router. An ATA enables you to adapt standard telephones to work with VoIP services. It plugs into your existing router. A VoIP router can be used as a replacement for an existing wired or wireless router. Typical VoIP routers support most or all of the following features:

    • Quality of Service (QoS) support— This feature prioritizes streaming media such as VoIP phone calls and audio or video playback over other types of network traffic.

    • One or more FXO ports— An FXO port enables standard analog telephones to be used in VoIP service.

    • Real-time Transport Protocol/Real-time Transport Control Protocol (RTP/RTCP)— Supports streaming media, video conferencing, and VoIP applications.

    • Session Initiation Protocol (SIP) support— A widely used VoIP signaling protocol also used for multimedia distribution and multimedia conferences.

Labels:

2012-05-21

A+: Network Topologies and Ethernet

The physical arrangement of computer, cables, and network devices is referred to as a network topology. There are four different types of network topologies:

    • Bus— Computers in a bus topology share a common cable. Connections in this topology are made largely with coaxial 10BASE2 and 10BASE5 cables. The network goes down if a single computer on a bus-topology network fails, but the other network types stay up if one or more computers fail.

    • Star— Computers in a star topology connect to a central hub or switch (wired) or access point (wireless). This topology is used by 10BASE-T (10 Mbps Ethernet), 100BASE-T (Fast Ethernet), and 1000BASE-T (Gigabit Ethernet) Ethernet networks and by Wireless Ethernet (Wi-Fi) when configured for the default infrastructure mode.

    • Ring— Computers in a ring topology either connect as a physical ring, for example FDDI networks; or a logical ring, as is the case with Token Ring networks.

    • Peer-to-peer (Mesh)—Computers in a peer-to-peer or mesh topology can connect directly to every other computer. This topology is used by computers with multiple network adapters, Wireless Ethernet (Wi-Fi) when configured for peer-to-peer mode, and Bluetooth.

Ring and Bus topologies are obsolescent; Star and Peer-to-peer rule.


Ethernet uses the Carrier Sense Multiple Access/Collision Detect (CSMA/CD) method of transmission access. Here’s how it works: A station on an Ethernet network can transmit data at any time; if two stations try to transmit at the same time, a collision takes place. Each station waits a random amount of time and then retries the transmission.

Wired Ethernet: The oldest network in common use today is Ethernet, also known as IEEE-802.3. Most recent wired Ethernet networks use unshielded twisted pair (UTP) cable, but older versions of Ethernet use various types of coaxial cable.

Wireless Ethernet is also known as IEEE 802.11, is the collective name for a group of wireless technologies that are compatible with wired Ethernet; these are referred to as wireless LAN (WLAN) standards. Wireless Ethernet is also known as Wi-Fi, after the Wireless Fidelity (Wi-Fi) Alliance (www.wi-fi.org), a trade group that promotes interoperability between different brands of Wireless Ethernet hardware.  Wi-Fi certified hardware is 802.11-family Wireless Ethernet hardware that has passed tests established by the Wi-Fi Alliance. Most, but not all, 802.11-family Wireless Ethernet hardware is Wi-Fi certified.
 
Wireless Ethernet hardware supports both the star (infrastructure) network topology, which uses a wireless access point to transfer data between nodes, and the peer-to-peer topology, in which each node can communicate directly with another node.


Labels:

2012-05-20

A+: Ports

For two computers to communicate they must both use the same protocol. In order for an application to send or receive data it must use a particular protocol designed for that application, and open up a port on the network adapter to make a connection to another computer. For example, let us say you wished to visit www.google.com. You would open up a browser and type http://www.google.com. The protocol being used is HTTP, short for Hypertext Transfer Protocol. That is the protocol that makes the connection to the web server: google.com. The HTTP protocol would select an unused port on your computer (known as an outbound port) to send and receive data to and from google.com. On the other end, google.com’s web server will have a specific port open at all times ready to accept sessions. In most cases the web server’s port is 80, which corresponds to the HTTP protocol. This is known as an inbound port.

If the port is blocked, the service it depends on will fail.

Port Protocol
21 FTP
22 SSH
23 Telnet
25 SMTP
53 Kerberos
80 HTTP
110 POP3
443 HTTPS
1863 Kinect Sensor
3074 XBOX 360

Labels:

2012-05-19

A+: TCP/IP Applications and Technologies

TCP/IP actually is a suite of protocols used on the Internet for routing and transporting information. Here are   some of the application protocols that are part of the TCP/IP suite, as well as some of the services and technologies that relate to TCP/IP.


ISP: An ISP (Internet service provider) provides the connection between an individual PC or network and the Internet. ISPs use routers connected to high-speed, high-bandwidth connections to route Internet traffic from their clients to their destinations.


HTTP/HTTPS: Hypertext Transfer Protocol (HTTP) is the protocol used by web browsers, such as Internet Explorer and Netscape Navigator, to access websites and content. Normal (unsecured) sites use the prefix http:// when accessed in a web browser. Sites that are secured with various encryption schemes are identified with the prefix https://.   Most browsers connecting with a secured site will also display a closed padlock symbol onscreen.


SSL: Secure Socket Layers (SSL) is an encryption technology used by secured (https://) websites. To access a secured website, the web browser must support the same encryption level used by the secured website (normally 128-bit encryption) and the same version(s) of SSL used by the website (normally SSL version 2.0 or 3.0).


TLS: Transport Layer Security (TLS) is the successor to SSL. SSL3 was somewhat of a prototype to TLS, and was not fully standardized. TLS was ratified by the IETF in 1999. However, many people and companies may still refer to it as SSL.


HTML: Hypertext Markup Language (HTML) is the language used by web pages. An HTML page is a specially formatted text page that uses tags (commands contained in angle brackets) to change text appearance, insert links to other pages, display pictures, incorporate scripting languages, and provide other features. Web browsers, such as Microsoft Internet Explorer and Netscape Navigator, are used to view and interpret the contents of web pages, which have typical file extensions such as .HTM, .HTML, .ASP (Active Server pages generated by a database), and others.

You can see the HTML code used to create the web page in a browser by using the View Source or View Page Source menu option provided by your browser.

Tags such as <P> are used by themselves, and other tags are used in pairs. For example, <A HREF...> is used to indicate the start of a hyperlink (which will display another page or site in your browser window), and </A> indicates the end of a hyperlink.

The World Wide Web Consortium (http://www.w3c.org) sets the official standards for HTML tags and syntax, but major browser vendors, such as Microsoft and Netscape, often modify or extend official HTML standards with their own tags and syntax.


FTP: File Transfer Protocol (FTP) is a protocol used by both web browsers and specialized FTP programs to access dedicated file transfer servers for file downloads and uploads. When you access an FTP site, the site uses the prefix ftp://.

Windows contains ftp.exe, a command-line FTP program; type FTP, press Enter, and then type ? at the FTP prompt to see the commands you can use.

FTP sites with downloads available to any user support anonymous FTP; if any credentials are required, it’s typically the user’s email address as a password (the username is preset to anonymous). Some FTP sites require the user to log in with a specified username and password.

Although you can use Windows’ built-in FTP client for file uploads and downloads with both secured and unsecured FTP sites, you should consider using third-party FTP products such as FileZilla (http://filezilla-project.org/) or WS_FTP Pro (http://www.ipswitchft.com/products/ws_ftp_professional/). These programs enable you to create a customized setup for each FTP site you visit, and will store passwords, server types, and other necessary information. They also enable faster downloads than typical web browsers running in ftp:// mode.


Telnet: Telnet enables a user to make a text-based connection to a remote computer or networking device and use it as if he were a regular user sitting in front of it, rather than simply downloading pages and files as he would with an http:// or ftp:// connection. Windows contains a command-line Telnet program. To open a connection to a remote computer, enter a command such as        telnet a.computer.com

To use other commands, open a command prompt, type telnet, and press the Enter key. To see other commands, type ?/help.

The remote computer must be configured to accept a Telnet login. Typically, TCP port 23 on the remote computer must be open before a login can take place.


SSH: Secure Shell (SSH) allows data to be exchanged between computers on a secured channel. This protocol offers a more secure replacement to FTP and TELNET. The Secure Shell server housing the data you want to access would have port 22 open.



DNS: The domain name system (DNS) is the name for the network of servers on the Internet that translate domain names, such as www.informit.com, and individual host names into their matching IP addresses. If you manually configure an IP address, you typically provide the IP addresses of one or more DNS servers as part of the configuration process.

Can’t access the site you’re looking for? Got the wrong site? You might have made one of these common mistakes:

        • Don’t assume that all domain names end in .com— Other popular domain name extensions include .net, .org, .gov, .us, .cc, and various national domains such as .uk (United Kingdom), .ca (Canada), and many others.

        • Don’t forget to use the entire domain name in the browser— Some browsers will add the www. prefix used on most domain names, but others will not. For best results, spell out the complete domain name.


If you want a unique domain name for either a website or email, the ISP that you will use to provide your email or web hosting service often provides a registration wizard you can use to access the domain name registration services provided by various companies such as VeriSign.

A domain name has three major sections, from the end of the name to the start:

    • The top-level domain (.com, .org, .net, and so on)

    • The name of the site

    • The server type; www indicates a web server, ftp indicates an FTP server, mail indicates a mail server, and search indicates a search server

For example, Microsoft.com is located in the .com domain, typically used for commercial companies. Microsoft is the domain name. The Microsoft.com domain has the following servers:

    • www.microsoft.com hosts web content, such as product information.

    • support.microsoft.com hosts the Microsoft.com support website, where users can search for Knowledge Base (KB) and other support documents.

    • ftp.microsoft.com hosts the File Transfer Protocol server of Microsoft.com; this portion of the Microsoft.com domain can be accessed by either a web browser or an FTP client.

Many companies have only WWW servers, or only WWW and FTP servers.

Some small websites use a folder under a domain hosted by an ISP: www.anisp.com/~asmallsite





Email: All email systems provide transfer of text messages, and most have provisions for file attachments, enabling you to send documents, graphics, video clips, and other types of computer data files to receivers for work or play. Email clients are included as part of web browsers, and are also available as limited-feature freely downloadable or more-powerful commercially purchased standalone email clients. Some email clients, such as Microsoft Outlook, are part of application suites (such as Microsoft Office) and also feature productivity and time-management features.

Users who travel away from corporate networks might prefer to use a web-based email account, such as Hotmail, or use Outlook Web Access to get access to email from any system with a properly configured web browser.

To configure any email client, you need

    • The name of the email server for incoming mail
    • The name of the email server for outgoing mail
    • The username and password for the email user
    • The type of email server (POP, IMAP, or HTTP)

Some email clients and servers might require additional configuration options.

To access web-based email, you need

    • The website for the email service
    • The username and password


SMTP: The simple mail transfer protocol (SMTP) is used to send email from a client system to an email server, which also uses SMTP to relay the message to the receiving email server.


POP: The post office protocol (POP) is the more popular of two leading methods for receiving email (IMAP is the other). In an email system based on POP, email is downloaded from the mail server to folders on a local system. POP is not a suitable email protocol for users who frequently switch between computers, because email might wind up on multiple computers. The POP3 version is the latest current standard. Users that utilize POP3 servers to retrieve email will typically use SMTP to send messages.

    For users who must use POP-based email and use multiple computers, a remote access solution, such as Windows Remote Desktop or a service such as GoToMyPC, is recommended. A remote access solution enables a user to remotely access the system that connects to the POP3 mail server so he or she can download and read email messages, no matter where he or she working.


IMAP: The Internet message access protocol (IMAP) is an email protocol that enables messages to remain on the email server so they can be retrieved from any location. IMAP also supports folders, so users can organize their messages as desired.

To configure an IMAP-based email account, you must select IMAP as the email server type, and specify the name of the server, your user name and password, and whether the server uses SSL.


Labels:

2012-05-18

A+: LANs, Internet Connectivity and Network Protocols

A LAN is an ideal way to provide Internet access to two or more users. However, a LAN by itself cannot connect to the Internet. Two additional components must also be used with a LAN to enable it to connect to the Internet:

    • An Internet access device— This could be a dial-up modem, but more often a broadband connection such as DSL, cable, or satellite is used.

    • A router—This device connects client PCs on the network to the Internet through the Internet access device. To the Internet, only one client is making a connection, but the router internally tracks which PC has made the request and transmits the data for that PC back to that PC, enabling multiple PCs to access the Internet through the network.

As an alternative to a router and modem or codec, some small networks use a gateway, which is a PC configured to share its Internet connection with others on the network. Windows 2000 and later versions support this feature, known as Internet Connection Sharing. Note that wireless access devices known as gateways actually resemble routers.


Network Protocols


The 2009 A+ Certification Exams expect you to understand the major features of network protocols TCP/IP and NetBEUI/NetBIOS.Although most current networks are based on TCP/IP, you might encounter others in some networks.


TCP/IP is short for Transport Control Protocol/Internet Protocol. It is a multiplatform protocol used for both Internet access and for local area networks. TCP/IP is used by Novell NetWare 5.x and later and Windows Vista/XP/2000 as the standard protocol for LAN use, replacing NetBEUI (used on older Microsoft networks) and IPX/SPX (used on older versions of Novell NetWare). Using TCP/IP as a network’s only protocol makes network configuration easier because users need to configure only one protocol to communicate with other network clients, servers, or with the Internet.
   
Most networking you’ll perform in the real world uses TCP/IP. TCP/IP is also the most complex network to configure, especially if you need to use a static IP address.


NetBEUI (NetBIOS Extended User Interface), the simplest protocol, is an enhanced version of an early network protocol called NetBIOS (NetBIOS itself is no longer used for this purpose). Historically, NetBEUI was used primarily on peer networks using Windows, with direct cable connection between two computers, and by some small networks that use Windows NT Servers. NetBEUI lacks features that enable it to be used on larger networks: It cannot be routed or used to access the Internet.

NetBEUI is not officially supported in Windows XP or Vista, although Microsoft provides the NetBEUI protocol on the XP distribution CD in the Valueadd\MSFT\Net\NetBEUI folder for use with older networks or for troubleshooting. For details on how to install NetBEUI in Windows XP, see the Microsoft Knowledge Base article 301041 available at http://support.microsoft.com/kb/301041. NetBIOS can be used in conjunction with TCP/IP in Windows XP and Vista.


Labels:

2012-05-17

A+: Broadband Internet Services (DSL, Cable, Satellite)

Broadband Internet service is a blanket term that refers to the following Internet access methods: digital subscriber line (DSL), cable, and satellite. All of these methods provide bandwidth in excess of 300Kbps, and current implementations are two-way services, enabling you to use your telephone while accessing the Internet. Other types of broadband Internet service, including direct wireless (using microwave transceivers) and powerline, are not part of the A+ Certification exam domains, but you might encounter them in some areas.

DSL (Digital Subscriber Line), like ISDN, piggybacks on the same telephone line used by your telephone and fax machine, but it differs from ISDN in many ways. Like ISDN, DSL requires a high-quality telephone line that can carry a digital signal, but unlike ISDN, DSL is designed strictly for Internet access.

When it comes to connection speed, DSL leaves BRI ISDN in the dust. There are two major types of DSL: ADSL (Asynchronous DSL and the predominant version) and SDSL (Synchronous DSL). 

A device known as a DSL modem is used to connect your computer to DSL service. DSL modems connect to your PC through the RJ-45 (Ethernet) port or the USB port.  DSL uses the same telephone lines as ordinary telephone equipment. However, your telephone can interfere with the DSL connection. To prevent this, in some cases a separate DSL line is run from the outside service box to the computer with the DSL modem. However, if your DSL provider supports the self-installation option, small devices called microfilters are installed between telephones, answering machines, fax machines, and other devices on the same circuit with the DSL modem. Microfilters can be built into special wall plates, but are more often external devices that plug into existing phone jacks.

Some DSL connections are configured as an always-on connection similar to a network connection to the Internet. However, many vendors now configure the DSL connection as a PPPoE (point-to-point protocol over Ethernet) connection instead. A PPPoE connection requires the user to make a connection with a username and password. Windows Vista and Windows XP have native support through its Network Connection wizard. With older versions of Windows, the vendor must provide setup software.

Cable Internet
Cable Internet service piggybacks on the same coaxial cable that brings cable TV into a home or business. A few early cable ISPs used internal cable modems, which supported one-way traffic. (The cable was used for downloads and a conventional telephone line was used for uploads and page requests.) Virtually all cable Internet service today is two-way and is built upon the fiber-optic network used for digital cable and music services provided by most cable TV vendors.

Cable Internet can reach download speeds anywhere from 1Mbps up to 10Mbps or faster. Upload speeds are typically capped at 128Kbps, but some vendors now offer faster upload speeds in some plans. You can have cable Internet service without having cable TV.

Some cable TV providers use the same cable that carries cable TV for cable Internet service, while others run a separate cable to the location. When the same cable is used for both cable TV and cable Internet service, a splitter is used to provide connections for cable TV and Internet. The splitter prevents cable TV and cable Internet signals from interfering with each other. One coaxial cable from the splitter goes to the TV or set-top box as usual; the other one goes into a device known as a cable modem. Almost all cable modems are external devices that plug into a computer’s 10/100 Ethernet (RJ-45) or USB port.

A cable Internet connection can be configured through the standard Network properties sheet in Windows or with customized setup software, depending upon the ISP.
Satellite
 
Satellite Internet providers, such as HughesNet (previously known as DirecWAY, and, before that, as DirecPC), Starband, and WildBlue use dish antennas similar to satellite TV antennas to receive and transmit signals between geosynchronous satellites and computers. In some cases, you might be able to use a dual-purpose satellite dish to pick up both satellite Internet and satellite TV service.

Geosynchronous satellites orbit the Earth’s equator at a distance of 22,300 miles (approximately 35,000 kilometers). Because of their orbit and altitude, they remain in the same location in the sky at all times. In the Northern Hemisphere, you need an unobstructed view of the southern sky to make a connection. In the Southern Hemisphere, you need an unobstructed view of the northern sky to make a connection.

Satellite Internet services use external devices often called satellite modems to connect the computer to the satellite dish. They connect to the USB or Ethernet (RJ-45) port in a fashion similar to that used by DSL or cable modems.

The FCC requires professional installation for satellite Internet service because an incorrectly aligned satellite dish with uplink capabilities could cause a service outage on the satellite it’s aimed at. Setup software supplied by the satellite vendor is used to complete the process.









 

Labels:

2012-05-16

A+: ISDN, Hardware & Connections


 
ISDN (Integrated Services Digital Network) was originally developed to provide an all-digital method for connecting multiple telephone and telephony-type devices. such as fax machines, to a single telephone line and to provide a faster connection for teleconferencing for remote computer users. A home/small office-based connection can also provide an all-digital Internet connection at speeds up to 128Kbps. Line quality is a critical factor in determining whether any particular location can use ISDN service. If an all-digital connection cannot be established between the customer’s location and the telephone company’s central switch, ISDN service is not available or a new telephone line must be run (at extra cost to you!).

The telephone network was originally designed to support analog signaling only, which is why an analog (dial-up) modem that sends data to other computers converts digital signals to analog for transmission through the telephone network. The receiving analog modem converts analog data back to digital data.

To make an ISDN connection, your PC (and any other devices that share the ISDN connection) needs a device called an ISDN terminal adapter (TA). A TA resembles a conventional analog modem. Internal models plug into the same PCI, ISA, and PC Card slots used by analog modems, and external models use USB or serial ports. External TAs often have two or more RJ-11 ports for telephony devices, an RJ-45 port for the connection to the ISDN line, and a serial or USB port for connection to the computer.
Setting Up an ISDN Connection
ISDN connections (where available) are provided through the local telephone company. There are two types of ISDN connections, the Primary Rate Interface (PRI) and the lesser Basic Rate Interface (BRI).

A PRI connection provides 1.536Mbps of bandwidth, whereas a BRI interface provides 64Kbps (single-channel) or 128Kbps (dual-channel) of bandwidth. BRI is sold to small businesses and home offices; PRI is sold to large organizations. Both types of connections enable you to use the Internet and talk or fax data through the phone line at the same time.

A direct individual ISDN connection is configured through the network features of Windows with the same types of settings used for an analog modem connection. Configuring a network-based ISDN connection is done through the network adapter’s TCP/IP properties window. 
Most telephone companies have largely phased out ISDN in favor of DSL, which is much faster and less expensive.





Labels:

2012-05-15

A+: Dial-Up Internet Service Providers and Connections

An Internet service provider (ISP) provides a connection between the user with an analog (dial-up) modem (or other connectivity device) and the Internet. ISPs that provide dial-up access have several modems and dial-up numbers that their customers can access. The ISP’s modems are connected to the Internet via high-speed, high-capacity connections.

An ISP can be selected from many different sources:
• National companies
• Local or regional providers
• Specialized providers such as those that provide filtered, family-friendly access
Choose an ISP based on its rates, its reliability, or special services (such as content filtration or proprietary content) that are appropriate to your needs.
Creating a Dial-Up Connection
 
Windows Vista creates dial-up networking (DUN) connections within the Network and Sharing Center window. Windows XP and 2000 create DUN connections within the same window that stores other types of network connections:
• Windows XP stores all types of network connections in the Network Connections window.
• Windows 2000 stores all types of network connections in the Network and Dial-Up Connections window.

Note

 
If an ISP provides customized setup software, the software will usually create an icon for you in the folder used for DUN connections. This icon contains the settings needed to make your connection.
Requirements for a Dial-Up Internet Connection
 All ISPs must provide the following information to enable you to connect to the Internet:
• Client software, including the preferred web browser, dial-up information, and TCP/IP configuration information
• Dial-up access telephone numbers
• Modem types supported (33.6Kbps, 56Kbps, v.90, v.92)
• The username and initial password (which should be changed immediately after first login)
Even if the client software provided by the ISP configures the connection for you, you should record the following information in case it is needed to manually configure or reconfigure the connection:
The dial-up access telephone number— This might be different for different modem speeds. Users with a 56Kbps modem should know both the standard (33.6Kbps) and high-speed access numbers if different numbers are used.
The username and password— Windows will often save this during the setup of a DUN connection, but it should be recorded in case the system must be reconfigured or replaced.
The TCP/IP configuration— This is set individually for each dial-up connection through its properties sheet.
To determine this information, right-click the icon for the connection and select Properties.

2012-05-14

A+: Analog Modem Installation


The method used for physical installation of the modem varies with the modem type. To install a PCI modem, follow these steps:
Step 1. Take ESD precautions. (See Chapter 17, “Safety and Environmental Issues,” for details.)
Step 2. Open the system and locate an empty slot of the appropriate type.
Step 3. Remove the screw holding the slot cover in place.
Step 4. Remove the slot cover.
Step 5. Install the modem into the slot and fasten it into place with the screw previously used to secure the slot cover.
Step 6. Connect an RJ-11 telephone cable running from the telephone jack in the wall to the line connection.
Step 7. If desired, plug a telephone into the telco jack.
Step 8. Close the system and restart it.
Step 9. Install drivers as required.
You can drive yourself crazy trying to make a connection with your modem if you plug the RJ-11 telephone cord into the wrong jack. There are actually three ways to make this mistake:

• Plugging the RJ-11 cord into the phone jack instead of the line or telco jack on the modem
• Plugging the RJ-11 cord into the slightly larger RJ-45 jack used for 10/100/1000 Ethernet networking
• Plugging the RJ-11 cord into a HomePNA network card (which also has two RJ-11 jacks) instead of the modem
If you use the HomePNA network, check the network documentation for the correct way to connect your network card and your modem to the telephone line.


To install a PC Card modem, use these steps:
Step 1. Slide the PC Card modem into an empty PC Card slot of the appropriate type (Type II or Type III).
Step 2. After the operating system indicates the modem has been detected, attach the dongle (if appropriate).
Step 3. If the dongle has an RJ-11 plug, connect it to the telephone wall jack.
Step 4. For modems with a pop-out RJ-11 jack, release the jack.
Step 5. Connect an RJ-11 telephone cable between the RJ-11 connector on the PC Card or dongle and the wall jack.
Step 6. Install drivers as required.
To install an external modem, follow these steps:
Step 1. Connect the modem to a USB or serial port as appropriate.
Step 2. Connect the modem to AC power and turn it on (if necessary).
Step 3. If the modem is not detected automatically, use the operating system’s modem dialog in the Control Panel to detect the modem and install its drivers.

Labels:

2012-05-13

A+: Internet connectivity and dial-up modems

One of the best reasons to create a network of any size is to provide access to the Internet. 
Properly used, the term modem (modulator-demodulator) refers only to a device that connects to the telephone line and performs digital-to-analog or analog-to-digital conversions. However, other types of Internet connections such as satellite, wireless, DSL, and cable Internet also use the term modem, although they work with purely digital data; the proper term is codec (coder-decoder). When used by itself here, however, modem refers only to dial-up (telephone) modems.

Dial-Up Modems and Internet Connectivity

Until the late nineties, dial-up networking (DUN) had been the most common way for home and small businesses to connect to the Internet. Dial-up connections are often referred to as analog connections because the device used to make the connection is an analog modem, which connects to the Internet through an ordinary telephone line. Every time you connect to the Internet with a dial-up modem, you are making a network connection.

There have been various standards for analog modems used to make dial-up connections. Before the advent of so-called “56K” standards, the fastest dial-up connection possible was 33.6Kbps. Virtually all modems in recent systems or available for purchase support either the ITU v.90 or v.92 standards.

Although v.90 and v.92 modems are all designed to perform downloading at up to 56Kbps, FCC (Federal Communications Commission) regulations limit actual download speed to 53Kbps. Speeds greater than 33.6Kbps apply only to downloads from ISPs (Internet service providers) and their special modems. If you make a direct connection between two PCs, the fastest speed you can have in either direction is just 33.6Kbps (if both modems can run at least that fast).

Dial-Up Modem Technologies and Types

A modem sending data modulates digital computer data into analog data suitable for transmission over telephone lines to the receiving modem, which demodulates the analog data back into computer form. Modems share two characteristics with serial ports:
• Both use serial communication to send and receive information.
• Both often require adjustment of transmission speed and other options.
In fact, most external modems require a serial port to connect them to the computer; some external modems use the USB port instead.

Modems come in five types: add-on card, external, PC Card, motherboard-integrated, and mini-PCI card. Add-on card modems for desktop computers fit into a PCI expansion slot. External modems plug into a serial or USB port. PCMCIA (PC Card) modems are sometimes built in a combo design that also incorporates a 10/100 Ethernet network adapter. Many desktop computers have integrated modems, as do many notebook computers. However, some notebook computers that appear to have built-in modems actually use modems that use the mini-PCI form factor and can be removed and replaced with another unit.

Add-on card dial-up modems for desktop machines

Although some high-end add-on card and PC Card modems have a hardware UART (universal asynchronous receiver transmitter) or UART-equivalent chip, most recent models use a programmable digital signal processor (DSP) instead. Modems with a DSP perform similarly to UART-based modems, but can easily be reprogrammed with firmware and driver updates as needed. 

Low-cost add-on card and PC Card modems often use HSP (host signal processing) instead of a UART or DSP. HSP modems are sometimes referred to as Winmodems or soft modems because Windows and the computer’s processor perform the modulation, slowing down performance. HSP modems might not work with some older versions of Windows or non-Windows operating systems.

PC Card or PCMCIA dial-up modems


A typical PC Card modem can require a dongle, a proprietary cable that attaches to one end of the PC Card to enable the modem to plug into a standard telephone jack or telephone line. If the dongle is lost or damaged, the modem can’t be used until the dongle is replaced. 

Some PC Card modems use an integrated or pop-out RJ-11 jack instead of a dongle (it’s one less thing to lose or break as you travel). 

External serial port and USB attached dial up modems

External modems, must be connected to a serial or USB port. Serial port versions require an external power source (USB modems are usually powered by the USB port or hub), but the portability and front-panel status lights of either type of external modem make them better for business use in the minds of many users. 

Labels:

2012-05-12

A+: Peer-to-Peer

The network features built into Windows allow for peer servers: Computers can share resources with each other, and machines that share resources can also be used as client workstations. As with client/server networking, resources on peer servers can be accessed via universal naming convention or by mapping drive letters and printer ports on a client to server resources.

If mapped drive letters and printer ports are used in a peer-to-peer network, the same resource will have a different name, depending on whether it’s being accessed from the peer server (acting as a workstation) itself or over the network. 

In a simple two-station peer-to-peer network, each computer acts as a peer server to the other. One PC shares its external hard disk drive with another PC, which refers to the shared hard disk drive as F:\. The second PC  shares its printer with the first PC, which has mapped the shared printer to LPT2.

The peer server loads file and printer-sharing software to make printers and drives or folders available to others. Because a peer server is also used as a workstation, it is equipped in the same way as a typical workstation or standalone PC.



Labels:

2012-05-11

A+: Client/Server

The roles of each computer in a client/server network are distinctive, affecting both the hardware used in each computer and the software installed in each computer. In a client/server environment there are many advantages including centralized administration, better sharing capabilities, scalability, and possibly increased security.


Most departmental and larger networks are client/server networks. The networks controlled by Windows Server 2008 and 2003, Windows 2000 Server, and Novell NetWare servers are examples of client/server networks.


One example is a server with three workstations, each of which is using a different shared resource: One is using the server’s inkjet printer, one is printing to the server’s laser printer, and one is copying a file to the server’s RAID array.

Servers

A server is a computer on the network that provides other computers (called clients or workstations) with access to resources, such as disk drives, folders, printers, modems, scanners, and Internet access. Because these resources can be used by different computers over the network, they are called shared resources.
Servers can also be used for different types of software and tasks. For example, application servers run tasks for clients, file servers store data and program files for clients, and mail servers store and distribute email to clients.

Servers typically have more powerful hardware features than typical PCs, such as SCSI or SATA RAID arrays or network attached storage for hard disk storage, larger amounts of RAM, hot-swap power supplies, and server-optimized network adapters. However, because servers are not operated by an individual user, they often use low-performance integrated or PCI video and might be managed remotely rather than with a keyboard or monitor connected directly to the server.

Clients

A client is a computer that uses the resources on a server. Typical examples of client computers include Windows Vista, XP, and 2000. Depending on the network operating system in use, clients and servers can be separate machines or a client can act as a server and a server can act as a client. Clients can refer to servers either by assigning drive letters to shared folders or by using a Universal Naming Convention (UNC) path name to refer to the server.



Labels:

2012-05-10

A+: Networking

A network is a group of computers, peripherals, and software that are connected to each other and can be used together. Special software and hardware are required to make networks work.

Two or more computers connected together in the same office are considered a LAN (local area network). LANs in different cities can be connected to each other by a WAN (wide area network). The Internet represents the world’s largest network, connecting both standalone computers and computers on LAN and WAN networks all over the world.

At one time, it was necessary to use a network operating system (NOS) such as Novell NetWare to enable networking. However, current operating systems, including Windows, include the components needed for networking.

Windows Vista, XP, and Windows 2000 include the following NOS features, enabling systems running these operating systems to be used either as network clients or as peer network servers:
Client software— Enables systems to connect with other networks. Windows XP/2000 can connect to Windows and Novell NetWare networks, among others, and Windows Vista connects to Windows networks only by default.
Network protocols— Windows XP/2000 can utilize TCP/IP, IPX/SPX, and NetBEUI. Windows Vista uses TCP/IPv4 and TCP/IPv6 by default.
File and print sharing— Enables Windows systems to act as peer servers for Windows and Novell NetWare networks. 
Services— Enables specialized network services, such as shared printers, network backup, and more. 
As the network features found in Windows suggest, there are two major network models:
1. Client/server
2. Peer-to-peer
It’s important to understand the differences between them as you work with networks.

Labels:

2012-05-09

A+: More options for failing system devices with conflicts

If the device has a conflict with another device, you might be able to change the settings in the device’s Properties page/Resources tab. If the device is a legacy (non-PnP) device, you might need to shut down the system and reconfigure the card manually before you can use Device Manager to reset its configuration in Windows.


You can also use the Device Manager to disable a device that is conflicting with another device. To disable a device, follow these steps:

    Step 1. Click the plus (+) sign next to the device category containing the device.

    Step 2. Right-click the device and select Disable.

or

    Step 1. Right-click the device and select Properties.

    Step 2. On the General tab, look for the Device Usage display at the bottom of the window. Click the menu and select Do Not Use This Device (disable).   If you prefer to solve the problem with the device, click the Troubleshoot button.

Depending on the device, you might need to physically remove it from the system to resolve a conflict. To use the Device Manager to remove a device, follow these steps:

    Step 1. Click the plus (+) sign next to the device category containing the device.

    Step 2. Right-click the device and select Uninstall.

    Step 3. Shut down the system and remove the physical device.

or

    Step 1. Right-click the device and select Properties.

    Step 2. Access the Driver tab, and click the Uninstall button.

    Step 3. Shut down the system and remove the physical device.

Labels:

2012-05-08

A+: Options for solving failing system devices

When you have a malfunctioning device, you have several options for resolving the problem:

    • Look up the Device Manager code to determine the problem and its solution. (These are just a few examples of the codes you might see in Device Manager. For a complete list, see support.microsoft.com/kb/310123 .)

Code 1: Not configured properly, so update the driver.
Code 3: Driver could be corrupted, so uninstall-reinstall the driver.
Code 3: Your system might be running low on memory or other resources, so close some open apps and/or install more RAM.
Code 10: Device cannot start, so update the driver, and visit Microsoft KnowledgeBase article 943104 for more information.
Code 12: Device can't find adequate free resources to use; you must disable another device to use it, so use the Device Manager Troubleshooting Wizard to find the coflict, and disable or reconfigure the conflicting device, else you must disable the device.

    • Click the Troubleshoot button (if any) shown on the device’s General Properties tab; the button’s name and usage depends upon the problem.

    • Manually change resources. If the nature of the problem is a resource conflict, you can click the Resources tab and change the settings and eliminate the conflict if possible. Most recent systems that use ACPI power management don’t permit manual resource changes in Device Manager and also override any changes you might make in the system BIOS setup program. On these systems, if resource conflicts take place, you might need to disable ACPI power management before you can solve resource conflicts.

    • Manually update drivers. If the problem is a driver issue but an Update Driver button isn’t available, open the Driver tab and install a new driver for the device.




Labels:

2012-05-07

A+: Troubleshooting with Device Manager

If your computer has devices that are malfunctioning in a way that Device Manager can detect, or has devices that are disabled, they will be displayed as soon as you open Device Manager. If the Ports (COM and LPT) category displays a malfunctioning port, COM 2, displays an exclamation mark (!) in a yellow circle. The parallel printer port, LPT1, if disabled, shows a red X. If the malfunctioning or disabled device is an I/O port, such as a serial, parallel, or USB port, any device attached to that port cannot work until the device is working properly. 
Not every problem with a device shows up in Device Manager, but most problems with resource conflicts or drivers will be displayed there.
To troubleshoot problems with a device in Device Manager, open its Properties sheet by double-clicking the device. Use the General tab to display the device’s status and to troubleshoot a disabled or malfunctioning device.  If the device’s General Properties sheet lacks a solution button, look up the Device Manager error code and take appropriate action manually.

Labels: