Discussion Point Networking This chapter is long and includes complicated topics, even though it covers only some networking concepts. There are entire courses designed around networking technologies, such as CompTIA’s Network+. There are advanced certifications such as the Microsoft Certified System Engineer (MCSE) and Certified Novell Engineer (CNE) courses. There are even entire courses for single networking topics such as TCP/IP. This chapter will only familiarize the students with the networking concepts and help them set up simple networks, as per the requirements of the CompTIA A+ certification.
Even though MAC addresses are embedded into the NIC, some NICs will allow you to change the MAC address on the NIC. This is rarely done.
You’ve most likely seen coaxial cable before, although perhaps not in a networking situation. Your cable TV and antenna cables are coaxial, usually RG-59 or the highly shielded RG-6. Watch out for questions on the exams dealing specifically with networking hardware protocols trying to trip you up with television-grade coaxial answers!
Tech Tip PVC vs. Plenum Most workplace installations of network cable go up above the ceiling and then drop down through the walls to present a nice port in the wall. The only potential problem with cabling running through the walls and ceiling is that the protective sheathing for networking cables is made from plastic, and if you get any plastic hot enough, it will create smoke and noxious fumes. To reduce the risk caused by burning buildings, all cables have fire ratings. The two most common fire ratings are PVC and Plenum. PVC (Poly-Vinyl Chloride) has no significant fire protection. If you burn a PVC cable, it creates lots of smoke and noxious fumes. Burning Plenum cable creates much less smoke and fumes, but Plenum costs about three to five times as much as PVC. Most city ordinances require the use of Plenum-rated cable for network installations. Bottom line? Get Plenum!
Discussion Point Building Cables When building network cables, it is important to follow the 568 standards all the time. Even though 10BaseT uses only two pairs of cables (you can actually omit the other two pair), it is good practice to build the cable the right way all the time. Doing this is useful for two reasons: first, you will always be in the habit of making the cables the right way; and second, if the network upgrades to 100BaseT, you will not have to rebuild all those cables. Discussion Point Crossover Cables If you want to connect two computers, but do not have a hub, you can connect them directly with a crossover cable. The crossover cable “crosses over” the transmission and receiving wires to enable two computers to be directly connected. The crossover cable will work only if connected to two NIC cards directly, and it will not work if connected to a hub. A normal cable will not work when connecting two computers directly. You can purchase a crossover cable, or you can build one. Exercise Building Cables It is now time to build some cables. Ask the students to measure the distances from the hub to each device (PCs and printers). You can show a PowerPoint slide detailing the RJ-45 wiring diagrams as a reference for the duration of this exercise. Have the students make a few crossover cables first. Check each cable end for correct wiring. Ask the students to build at least enough cables to connect all the PCs (if you have ten PCs, you will need five crossover cables). To save resources, you can cut the crossover end off to build a normal cable after you do the first part of the installation exercise (peer-to-peer crossover network). Ask the students to build a few UTP cables using RJ-45 jacks. Check each cable end for correct wiring.
Tech Tip Crossover Cables You can actually hook two 10xBaseT network cards together without a hub by using a special UTP cable called a crossover cable. A crossover cable is a standard UTP cable, but it has one RJ-45 connector using the 568A standard and the other using the 568B standard. This reverses the signal between sending and receiving wires and thus does the job of a hub or switch. Crossover cables work great as a quick way to network two PCs. You can purchase a crossover cable at any computer store.
Tech Tip Multimode and Single Mode Light can be sent down a fiber optic cable as regular light or as laser light. Each type of light requires totally different fiber optic cables. Most network technologies that use fiber optics use LED, or Light Emitting Diodes, to send light signals. These LEDs use multimode fiber optic cabling. Multimode fiber optic transmits multiple light signals at the same time, each using a different reflection angle within the core of the cable. The multiple reflection angles tend to disperse over long distances, so multimode fiber optic cables are used for relatively short distances. Network technologies that use laser light use single-mode fiber optic cabling. Using laser light and single-mode fiber optic cables allows for phenomenally high transfer rates over incredibly long distances. Single-mode fiber optic cabling is currently quite rare; if you see fiber optic cabling, you can be relatively sure that it is multimode.
Tech Tip Modern Token Ring Networks Token Ring manufacturers have not rolled over and given in to the pressure of Ethernet standards, but rather have continued to adapt and innovate. Modern IEEE 802.5t Token Ring networks run at 100 Mbps or faster, and because the ring technology does not suffer from the overhead of CSMA/CD, you get phenomenally faster performance from High Speed Token Ring (HSTR) networks than from comparably speedy Ethernet. Check them out here: www.token-ring.com.
The terms “client” and “server” are, to say the least, freely used in the Windows world. Keep in mind that a client generally refers to any process (or in this context, computer system) that can request a resource or service, and a server is any process (or system) that can fulfill the request.
Discussion Point Administrator All NOSs have a special account called Administrator. Some NOSs may have a different name for that account, such as Root, but they all have one thing in common: they have access to anything and everything on the network. These super accounts control the entire network. Anyone who has access to this account can bring down an entire network. If you have an account with this privilege, you must not disclose the password to others. If you forget the password, you will need to completely reinstall the NOS.
A node is any device that has a network connection—usually this means a PC, but other devices can be nodes. For example, many printers now connect directly to a network and can, therefore, be termed nodes. I use the term node extensively in the rest of the chapter in place of PC or networked computer. This is especially true when I discuss wireless technologies, because that’s the term the manufacturers use.
If you have the option, you should save yourself potential headaches and troubleshooting woes by acquiring new, name-brand NICs for your Windows installation.
Exercise Installing the NIC Cards Now you can ask the students to install the NIC cards. Make sure they are installed and configured properly. If they are legacy cards, the students will need to set the resources manually, including the IRQ, I/O, and DMA. Depending on the card, they may have to set the jumpers, or they may need to boot to the Safe Mode command prompt (otherwise Windows may interfere with the installation) and install the Setup program on the accompanying installation disks to configure the resources. The students then reboot to Windows and install the NIC drivers. If they are PnP, installation should be easy. Verify the card is working in the Device Manager. Students benefit from installing PnP and legacy cards for orientation and experience.
Client Service for NetWare does not support the IP protocol used in NetWare 5. x .
When NWLink is set to autodetect the frame type, it will only detect one type, searching in the following order: (1) 802.2, (2) 802.3, and (3) 802.5.
The A+ Certification exams do not require you to configure IP addresses and subnet masks, but you should know what they are and how to find them on a PC.
Instructor Tip Use a chalkboard or whiteboard to demonstrate octets. It will be much easier for the students to pick up the concept this way. Discussion Point Octets The root of the word “octet” is “oct” meaning eight. Why is a three-digit number called an octet? Because each octet is a representation of an 8-bit binary number consisting of 1s or 0s. Starting from the right, the first digit has a value of 1, the next digit to the left has a value of 2, the next digit has a value of 4, and so on. Each number is double the previous one. You merely add the values of the digits together for the octet number. Value: 128 64 32 16 8 4 2 1 Binary: 0 1 0 0 1 1 1 0 Now add the value of each 1: 2 + 4 + 8 + 64 = 78 So, 01001110 equals 78. By converting each octet (1s and 0s) to its decimal form, you get a recognizable IP number such as 184.108.40.206. By adding the values of the 1s and 0s, you can quickly see that if you have all 1s, you have 255 (128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255) and if you have all 0s, you have 0.
Primary and Secondary DNS The primary DNS server is the first computer used to resolve Internet addresses to IP addresses. A backup computer is called the secondary DNS server. Internet Corporation for Assigned Names and Numbers (ICANN) If you want a domain name that others can access on the Internet, you must register your domain name and pay a small annual fee. Your Internet Service Provider (ISP) can probably handle this for you. These names are assigned by ICANN.
Use this optional slide to show that name resolution is handled in several different ways, but focus here is only on the DNS server and the WINS server.
Where are the TCP/IP settings? Windows 9 x /Me using modems: My Computer Dial-up Networking icon right-click the connection and select Properties Server Type TCP/IP Settings Windows 9 x /Me with a direct connection: Control Panel Networks TCP/IP Properties Windows 2000/XP: Right-click My Network Places and choose Properties right-click the connection and choose Properties double-click Internet Protocol (TCP/IP) and click the Advanced button for additional settings
Discussion Point Ping It is widely believed that Ping (an important network utility) is an acronym for Packet Internet Groper. This is not so. According to the author of Ping, Mike Muuss (who died in a car crash on November 21, 2000), he wrote the Ping program in 1983 to help track down a network disconnect. The computer he was working on would send out a small packet, and when it reached the destination, it would bounce back. He named it Ping because it reminded him of the ping sound of a submarine’s sonar. (Source: http:// ftp.arl.mil/~mike/ping.html )
Make sure you know that Windows 9 x /Me uses WINIPCFG and Windows NT/2000/XP uses IPCONFIG.
You can do cool stuff with NSLOOKUP; some techs absolutely love the tool. It’s way outside the scope of A+ Certification, but if you want to play with it, type help at the NSLOOKUP prompt and press ENTER to see a list of common commands and syntax.
Each line indicates a router
Discussion Point Share Names Simply naming a shared drive with C is usually not a good idea because a network user could confuse your C with someone else’s C. It is best to give the drive a unique name. You can name it for the person using that computer all the time (Dave), by content (MP3s), the desk position (Desk4), or anything else you want, so long as it is easy for network users to figure out what drive it is.
Windows NT/2000/XP has two types of sharing: Network permissions and NTFS permissions. Windows 9 x /Me has only Network permissions.
All shared resources should show up in Network Neighborhood/My Network Places. If a shared resource fails to show up, check the basics first: Is File and Print Sharing activated? Is the device shared? Don’t let silly errors fool you!
The A+ Core Hardware Exam loves questions on cables and connectors, so look for questions on USB adapters and WAPs.
Changing the default SSID for a WAP is the first step in securing a wireless network.
HomeRF HomeRF, as the name implies, is intended for home use, not for use in large business network environments. It is easy to set up and maintain but doesn’t offer much in the way of range (about 150 feet, maximum). Early HomeRF devices were fairly slow, clocking in at a maximum of 2 Mbps, but the later version 2.0 operates at a respectable 10 Mbps and also provides full backward-compatibility with the earlier HomeRF technology. HomeRF wireless networks use the SWAP protocol, a hybrid of the Digital Enhanced Cordless Telecommunications (DECT) standard for voice communication and the 802.11 wireless Ethernet standard for data. HomeRF uses seven channels in the 2.4-GHz range, six of which are dedicated to voice communication with the remaining one used for data. Because HomeRF devices use the FHSS spread-spectrum broadcasting method, they are less prone to interference and somewhat more secure than Wi-Fi devices. HomeRF uses a proprietary 56-bit (128-bit in version 2.0) encryption algorithm instead of the industry-standard WEP and WPA that 802.11 uses. Also, instead of an SSID name, HomeRF uses what is called a network ID (NWID), which is somewhat more secure.
Tech Tip Increasing Wireless Range Range can be increased in a couple of ways. First, you can install multiple WAPs to permit “roaming” between one WAP’s coverage area and another’s—an EBSS, as described earlier in this chapter. Second, you can install a signal booster that increases a single WAP’s signal strength, thus increasing its range.
Look for basic troubleshooting questions on the A+ Certification exams dealing with factors that affect wireless connectivity, range, and speed.
Exercise Troubleshooting the Network As with all other troubleshooting exercises, your goal here is to set up a “service call” for the students. You want them to go into diagnostics mode to figure out what the problems might be. In networking, you have tons of places to change settings surreptitiously, disconnect cables, use known bad cables, or use a crossover cable with a hub or a normal cable when directly connecting two computers. Alter TCP/IP settings, unplug the hub, and so on, to disable the network or network connection.
Pairs of wires are twisted together in an unshielded cable
UTP cables come in categories (CATs) that define the maximum speed data can be transferred
CAT5, CAT5e, and CAT6 are most common today
CAT 1 Standard phone line CAT 2 ISDN & T1 lines Speeds up to 4 Mbps CAT 3 Speeds up to 16 Mbps CAT 4 Speeds up to 20 Mbps CAT 5 Speeds up to 100 Mbps CAT 5e Speeds up to 1 Gbps CAT 6 Speeds up to 10 Gbps
Name Type Static Dynamic Cache Host Internet name HOSTS file DNS server Hosts cache View with IPConfig /DisplayDNS NetBIOS Windows name LMHosts file WINS server NetBIOS cache View with NBTSTAT –C Broadcast
Layer Number Name Description Layer 1: Please Physical NICs (link light), cables, switches, hubs, etc. 1s, 0s Layer 2: Do Data Link MAC addresses and CSMA/CD Layer 3: Not Network IP operates here Layer 4: Throw the Transport TCP/UDP operate here Layer 5: Sausage Session Manages connections Layer 6: Pizza Presentation Describes how to present data Layer 7: Away Application Interacts with user