Home Networking Annoyances: How to Fix the Most Annoying Things about Your Home Network
ENTERING INFORMATION FROM YOUR ISP
The Annoyance:
My ISP said to configure my network adapter to "Obtain an IP address automatically" and enter the IP address provided by my ISP for the DNS server. The instructions say to enter that data in either the Local Area Network Properties dialog box or the router's configuration pages. Which is the best choice? The Fix:
You don't really have a choice. If you installed a router, the ISP's instructions should have told you to enter the DNS server information in the router's configuration software. If you're using Internet Connection Sharing instead of a router to share your Internet connection, you have to enter the DNS server information in the Local Area Network Properties dialog box on the computer that's hosting the connection (the computer that has the modem). GETTING TO THE ROUTER
The Annoyance:
An article on the manufacturer's web site suggested I make a change to the router's configuration to resolve a problem we're having. A consultant walked me through the original setup, and I can't find the documentation. How do I open the router's configuration pages? The Fix:
Assuming you didn't change the router's login name and password, you can get into the router's setup pages by opening your browser and entering the router's IP address in the Address Bar. The IP address is provided in the documentation, and all the major manufacturers offer a copy of the manual for download (usually a PDF file, so you'll need Acrobat Reader). However, to save you some time, the following list gives you the default IP addresses of the routers from some of the most popular vendors:
A login screen appears, looking something like Figure 2-2. Again, assuming the login name and password haven't been changed, and the default values are in place, enter the login data using the values in Table 2-1. These values are valid for the routers in the last year or so, but manufacturers can change the defaults as they upgrade their models, so check the documentation. Figure 2-2. Log in to the router's configuration utility.
Warning: Login names and passwords are case-sensitive.
LOST ROUTER LOGIN NAME OR PASSWORD
The Annoyance:
I did one of those stupid things you always read warnings aboutI lost the piece of paper on which I'd written the login name and password I created for our router's configuration utility. I need to make an adjustment to a setting, but I can't get into the router's configuration pages. The Fix:
You must start all over by putting the router back to its factory settings. The factory settings include the original default login name and password. However, the factory settings don't account for all the configuration options you set. Locate the reset button on the router. Press and hold the button for at least 30 seconds, though 60 seconds is preferable. Depending on the manufacturer, you might see a link light change color when the router's settings have been returned to the factory defaults. Now use the manufacturer's default login and password (listed in Table 2-1) to enter the configuration utility. Go through all the dialog boxes or wizards to reset your router for your network. WHY CHANGE THE LOGIN DATA FOR ROUTERS?
The Annoyance:
I don't see any reason to change the default login and password for my router's configuration utility because it's just one more password to remember. My home network isn't in the middle of a public place, where strangers can get into the utility and mess up my network. What's the harm in leaving the default data alone? The Fix:
If your network is physically secure (the computers are not publicly accessible and you're not using wireless technology for your network), there are no negative side effects to leaving default values in place. However, you need to think carefully about the term "physically secure." I'll give you some things to think about based on the calls I've received from clients whose networks stopped performing properly because somebody messed around with settings. Is there someone in your household who knows just enough about computers to be dangerous? These are people who can figure out how to get into dialog boxes and program settings, and are totally fearless about making changes because they think they know what they're doing. Of course, they usually don't know what they're doingthey know only enough to be dangerous. These folks aren't malicious, just well meaning and incompetent. Is there someone in your household who lets outsiders who might fall into the "knows enough to be dangerous" category work on one of your network computers? For example, do your teenagers invite friends to share network games or work on homework assignments together? Do you meet people who sound like geeks at social occasions, and ask them (or hire them) to help you tweak your settings? Approach the hiring of a computer consultant the same way you'd approach hiring an electrician or plumberask people for recommendations before you give anyone login names and passwords.
WHAT'S DHCP AND WHERE CAN I GET SOME?
The Annoyance:
I had intermittent problems with computers that suddenly couldn't be accessed across the network. I wrote to the router manufacturer's tech-support team, and they sent email advising me to change the duration of DHCP leases. What? Huh? The Fix:
DHCP (Dynamic Host Configuration Protocol) is a system in which a server, configured to be a DHCP server, assigns IP addresses to all the computers on the network the server serves. The DHCP server depends on your network setup:
When you configure your network adapter to "Obtain an IP address automatically," the address is obtained from a DHCP server. DHCP "leases" an IP address to each computer for a given amount of time. If a computer is still connected to the network when the lease expires, it's automatically renewed. If you restart the computer, a new lease is issued during Windows startup. If you want to know the current terms of your IP address lease, first open a command window. Do this by clicking Start Figure 2-3. The DHCP server for this computer is giving out leases that last 24 hours.
Each DHCP server is equipped with a range of IP addresses that it can assign to the computers on the network. By default, most routers assign a lease for 24 hours, but you can change the duration by entering the router's configuration utility. The dialog box, the name of the option, and the choices you have depend on the manufacturer of your router, so you have to read the manual. MAC ADDRESS? I DON'T HAVE A MAC!
The Annoyance:
According to a knowledge base article on my router manufacturer's web site, the problems I'm having might be related to a problem with MAC addresses. I'm supposed to delete the computers from my router and then boot them back into the network, but I don't have any MACs on my network. The Fix:
In this context, the term MAC has nothing to do with Macintosh computers. MAC stands for Media Access Control, which is a unique number for a computer. The number is related to a piece of hardware, which is the network adapter in a small network. The DHCP server also tracks the IP address it assigns each computer and links that IP address to the computer's MAC and the computer's name. This feature lets you access network computers by name using My Network Places or Network Neighborhood. The network doesn't access the computer by name; it works with IP addresses. Your router's database links the names, MAC addresses, and current IP addresses. You can find that database, which is usually called the Client Table (or something similar), in your router's configuration utility. Look for a tab by that name, or go to the DHCP tab and look for a button or link with that name. Figure 2-4 shows a typical Client Table for a small network. Figure 2-4. If you delete a computer, the router rediscovers it the next time it logs on to the network.
OH NO, MY COMPUTER IS USING APIPA
The Annoyance:
I couldn't get to the Internet from any of the computers on my network. I called a friend, who told me to check the IP addresses of my network computers by typing ipconfig at the command line. Then he told me my computers were using APIPA, which meant my router wasn't working. What in the world is APIPA, and how did it break my router? The Fix:
APIPA stands for Automatic Private IP Addressing, and it didn't break your router. It's a "last resort" feature computers use to communicate with each other when they don't get the IP addresses they expect from a DHCP server (in this case, your router). When communication between the DHCP server and a computer fails, the operating system automatically applies a unique private IP address to each computer. The APIPA addresses use the range 169.254.0.0 through 169.254.255.254. When you entered ipconfig at a command prompt, you could see that the IP address was within that range. When computers use APIPA addresses, everything on the network slows down. Computers boot slowly because there's the delay of looking for the DHCP server, and then, when no DHCP server is found, the computer must peek down the pipes (the wires or wireless RF signal) to see what other computers are on the network and what their APIPA addresses are. Finally, the computer gives itself an APIPA address that isn't in use. The computer also sets the subnet mask to 255.255.0.0. The APIPA address is considered temporary until a DHCP server is located, and in fact, the computer continues to search for one. If you're using APIPA addresses, it means your DHCP server (in this case, your router) isn't working. You need to check the connections and link lights on your router, and call the manufacturer's technical support line. SWITCHING LAPTOP IP ADDRESS SETTINGS BETWEEN WORK AND HOME
The Annoyance:
I have a laptop computer that I bring home from the office. At work I have a fixed IP address, and at home I have a router so that my network adapter is set to obtain an IP address automatically. Obviously, these settings don't match, and at home I can't get on the Internet. The systems administrator at work told me I could go through a zillion steps to create an alternate hardware profile for the computer so that my network adapter settings match each network. Then he said it was too complicated to explain, and it was too much work to do it for me. The Fix:
Upgrade your laptop to Windows XP. If you don't, I vote with your administratora hardware profile is too complicated to explain, set up, and use, so fugget-aboutit. Windows XP has a nifty feature for network adapters called "alternate configuration." It's available only if your main configuration is set to "Obtain an IP address automatically" (there's a DHCP server on the network), and the alternate configuration (the other network) doesn't have a DHCP server. You can set up the alternate configuration to use either an Automatic Private IP Address (APIPA) or a fixed IP address. In your case, you must change your adapter so that its primary settings are for your home network (which obtains an IP address automatically), and then enter the fixed IP address for work on the Alternate Configuration tab. To do this (after you've upgraded to Windows XP, of course), open the Properties dialog for the Local Area Connection, select the TCP/IP component, and click the Properties button. Write down all the settings for the adapter, which are the settings for work. Be sure to click the Advanced button and take notes on all the settings on all the tabs. Change the settings on the General tab to match the settings on your home network, then click the Alternate Configuration tab to enter the settings for work (see Figure 2-5). Now, when you log on to your home network, your laptop receives an IP address automatically. When you log on to the network at work, the computer reads the adapter's settings. Because the primary settings are for obtaining an IP address automatically, the system looks for a DHCP server. You don't have a DHCP server at work, so when the computer can't find a DHCP server, it checks the Alternate Configuration tab and uses the settings it finds. Very cool! Figure 2-5. Enter the TCP/IP settings for the "other" network.
Tip: If the TCP/IP Properties dialog box doesn't have an Alternate Configuration tab, your primary settings are for a fixed IP address or for an APIPA address. The Alternate Configuration tab appears only when the primary settings are configured to "Obtain an IP address automatically." CAN'T LOG ON TO DIFFERENT NETWORKS WITH ALTERNATE CONFIGURATION
The Annoyance:
I configured my network adapter for alternate IP address configurations because I have a fixed IP address at work and a router that provides DHCP addresses at home (which is the primary configuration setting). I went to the Microsoft web site and found the following statement: "If you are a mobile computer user, you can use the Alternate Configuration functionality to maintain seamless operations on both office and home networks without having to manually reconfigure TCP/IP settings." After I set up my laptop for my home network I couldn't log on to the system at work, so the IT department reconfigured my computer for work. Now I can't access resources on my home network. This is what Microsoft calls "seamless"? I don't think so. The Fix:
I suspect that marketing departments tend to oversimplify stuff (is that a polite, politically correct statement, or what?). That assertion means "seamless TCP/IP settings," not "seamless logons." Take a look at the data on the Computer Name tab of the System Properties dialog box (right-click My Computer and choose Properties to get there). Your computer identification setup probably looks a lot like mine, which you can see in Figure 2-6. My computer is set up to log on to my company domain, which has fixed IP addresses, while my home network has a router that supplies IP addresses. I don't have any trouble logging on to the company domain, because the computer fails to find a DHCP server and then uses the alternate configuration. When I want to log on to my home network, I choose Local Computer in the logon dialog box (which has that option because the computer is configured for a domain logon). I can get to resources on the other computers on the network by using the Run command (\\ComputerName\Sharename). The other computers can't find this computer in Network Neighborhood or My Network Places. Because my laptop has no files or resources that the other computers on my home network need, I haven't bothered to figure out a way for the other computers to get to my laptop. Needless to say, this isn't efficient, so I looked for a better way. (See the next annoyance.) Figure 2-6. This computer is configured to log on to a domain, not a workgroup.
NETWORK SWITCHING PROGRAMS
The Annoyance:
I move my laptop between my office, home network, four client sites, airport hot spots ...well, you get the idea. I spend half my work life trying to reconfigure my computer, and the other half dealing with error messages and trying to use a browser to connect to a network share. The Fix:
Sheesh! I only connect between my corporate and home networks and that drives me nuts. I can't imagine how you keep your sanity. I've discovered the solutionsoftware designed to save computer settings and load them as needed. I'll mention two of these applications, NetSwitcher and Mobile Net Switch, because they've both received excellent reviews from respected sources. NetSwitcher saves your network settings so that you can load them as needed. After you install the software, save your current configuration. Then select the command to define a different set of network settings, and enter the configuration for another network. Each set of configuration settings is called a location. When you boot the computer, select the location for the network you're joining. You can learn more about NetSwitcher at http://www.netswitcher.com. Mobile Net Switch works similarly to NetSwitcher. However, for Windows 2000 or earlier, you must download and install some additional files (the Windows Management Instrumentation component, which is not installed in earlier Windows versions). You can learn more about Mobile Net Switch at http://www.mobilenetswitch.com. LAPTOP HAS MULTIPLE LOCAL NETWORK CONNECTIONS
The Annoyance:
My laptop settings show two LAN connection items with identical properties. However, I own only one adapter. What's going on? The Fix:
You don't use the same slot every time you insert your PC Card (sometimes called PCMCIA) network adapter. Windows sees each slot as a unique device, and keeps information on devices even when they're removed from the computer. At any given moment, one of those connections is showing an errorthe one that Windows thinks should be in the slot you're not using at that moment (see Figure 2-7). If the adapter is for a wired network, the error says the cable is unplugged. For a wireless network, the error says no signal can be found. Figure 2-7. Windows notices that one of the connections isn't available and displays an error.
You can ignore the error, and ignore the fact that your computer has two connections, without harm. If it really bothers you, decide once and for all which slot you want to use for your PC Card and remember to use that slot all the time. Then disable or remove the other LAN connection.
To open the Device Manager, right-click My Computer and choose Properties to open the System Properties dialog box. In Windows XP and 2000 select the Hardware tab, and then click the Device Manager button. In Windows 98SE and Me, click the Device Manager tab. Warning: If you use the "other" PC Card slot in the future, your "disabled" connection will automatically be enabled, and the currently enabled connection will display an error. If you uninstalled the "other" connection, Windows will automatically go through an installation procedure.
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