All communications with the outside world have been cut off. Your children are crying. Your spouse/partner is screaming. Even the family dog seems unsettled.
The start of a horror movie? No, it’s even scarier. The Internet is down, and nobody knows why.
How will you know what your high school friend ate for breakfast? What will your son destroy without Xbox Live to keep him busy? Will you be the last person on earth to see that hilarious new meme with the dog talking on the telephone?
Fortunately, a powerful hero has risen to restore the Internet: you. Using some basic networking knowledge and the troubleshooting techniques described in this chapter, you can diagnose the cause of network problems (including complete outages and performance issues). In many cases, you might be able to solve them yourself. When you can’t, you’ll know who to call, and you can skip past the worst part of the tech support guy’s script.
This section describes the most important tools for troubleshooting networks, in roughly the order you should use them. Windows has dozens of other network tools built in, but I’m only going to describe the few that you really need to know how to use. After I describe the tools, I’ll give you a step-by-step process you can follow for troubleshooting most home network problems.
“Have you tried turning it off and on again?”
That’s a quote from The IT Crowd, a fantastic British comedy. The main characters work in the technical support department, and they greet every phone call with that line.
It’s actually pretty sound advice. Restarting completes several tasks that can solve problems:
It stops all running software, including software that might be running in the background and misbehaving.
It unloads memory, temporarily solving memory leaks.
It resets all network connections, curing intermittent problems caused by software or network conditions that might overload buffers.
It reacquires network settings from the DHCP server, potentially retrieving updated settings.
For modems, it causes them to redownload settings from your ISP and reassess signal levels, and that updated information might improve the reliability of the connection.
Restarting obviously won’t solve recurring issues, but it should always be the first step you take to get yourself back online. If you later call tech support, it’s going to be the first thing they make you do, anyway.
Restart your equipment in the following order:
Modem
Router
Wireless access points, switches, and bridges (if separate from your router)
PCs or other network devices
Windows 8.1 includes automated tools that can diagnose and fix many types of problems. Yes, the tools do more than tell you to turn everything off and on (though they really will tell you to do that).
If you’re having a network problem, your first step in diagnosis is to open the Settings charm and check the network icon. If it shows a yellow triangle, as shown in Figure 23-1, that means Windows can’t communicate with the Internet.
Now, from the Start screen, search for network sharing center and select Network And Sharing Center. Within Network And Sharing Center, the Access Type field shows your current connection level. In Figure 23-2, it is No Network Access.
Figure 23-2. Access Type within Network And Sharing Center shows whether you can reach the local network or the Internet.
Access Type can have one of several different results:
No network access. Windows can’t access any network resources, including those on your local network. This means the problem is probably a PC configuration problem or a problem with your home network, including your wireless access point, router, or switch.
No Internet access. Windows can communicate on your local network, but it can’t reach the Internet. The problem could be with your PC’s network configuration, your wireless access point or router, or with your ISP. You’ll have to do some more troubleshooting to determine the exact source of the problem.
Internet. Everything is working, and Windows can communicate on the Internet. If you’re having a problem connecting to a website or some other network service, it’s probably that specific website or service. Contact them directly if you can think of a way to communicate with someone other than over the Internet.
Note that it might take several minutes for Network And Sharing Center to determine that you have lost Internet access or reconnected to the Internet, so if your network status changes, give it a few minutes. You can use Ping to more quickly check your Internet access, as described later in this chapter.
That narrows the problem down, but it doesn’t fix it, or even really tell you who to call. Your next step should be to use Network Diagnostics.
You can open Network Diagnostics by clicking the Troubleshoot Problems link in the Network And Sharing Center. You’ll see the prompt shown in Figure 23-3. Click Internet Connections.
Click Next. Network Diagnostics will then give you a choice of how to diagnose the problem, as shown in Figure 23-4. If you’re having general Internet problems, select the first option. If your problem is with a specific website, select the second option.
Network Diagnostics will spend a few minutes trying different things. Eventually, it will show you the results, as shown in Figure 23-5. Naturally, you might see different results depending on the nature of your problem.
Network Diagnostics isn’t perfect. In fact, it’s not even great. It will correctly diagnose a small portion of network problems, and it’s really easy to use, so I do recommend that people try it after they’ve restarted everything. However, most of the time, you’ll still have to do some manual troubleshooting to isolate your problem. The sections that follow describe some useful tools.
Ping is such a commonly used troubleshooting tool that it’s become part of the modern vocabulary, at least among the somewhat geeky people I hang around. As a verb, ping means to quickly make contact—for example, “I’ll ping you before I leave.” Ping has even made it into the Urban Dictionary.
Ping is a command-line tool, so you need to open the Command Prompt desktop app to use it. As a reminder, you can quickly open a command prompt by opening the WinX menu and then clicking Command Prompt.
Use Ping by specifying a destination address on your home network or on the Internet. For example:
ping northrup.org
Pinging northrup.org [74.125.228.3] with 32 bytes of data:
Reply from 74.125.228.3: bytes=32 time=122ms TTL=52
Reply from 74.125.228.3: bytes=32 time=83ms TTL=52
Reply from 74.125.228.3: bytes=32 time=688ms TTL=52
Reply from 74.125.228.3: bytes=32 time=39ms TTL=52
Ping statistics for 74.125.228.3:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 39ms, Maximum = 688ms, Average = 233msBy default, Ping sends four messages to the destination. In the previous output, you can see that Ping got responses to all four messages, meaning the PC can successfully communicate with the destination.
Besides the fact that you can communicate with a single host, the Ping output tells you quite a bit about your network conditions:
Your DNS server is properly configured and working, because Ping was able to resolve northrup.org to the IP address 74.125.228.3.
All four pings succeeded, meaning packets are being sent and received reliably. At times, some packets might be dropped, indicating an unreliable connection.
Your PC’s network adapter, your home network, and your ISP’s network are all working properly (at least for basic communications).
The round trip time (RTT) between the PC and the northrup.org server averages 233 milliseconds (ms). That’s a measure of the network latency, which measures the time it takes for communications to travel between two locations. In this example, the latency is moderately high.
The quickest RTT was 39 ms and the longest 688 ms. That’s a 1,700 percent difference, which means the network connection has very high jitter. Jitter is a measure of how much the latency varies.
That’s quite a bit of information to extract from one command. The other common results you might get from Ping are Request Timed Out and Destination Host Unreachable (which usually mean the same thing), as the following example demonstrates:
ping microsoft.com
Pinging microsoft.com [64.4.11.37] with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Ping statistics for 64.4.11.37:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),These results could indicate one of several different conditions:
You’ve completely messed up your home network.
Your ISP is on a lunch break.
Your neighbor with the backhoe didn’t call the electric company before digging and has broken through a very important underground cable.
The Internet has seen one too many cat photos and taken a much deserved vacation.
Microsoft.com is offline.
Microsoft.com doesn’t reply to pings.
As you can see, you can tell a great deal from a successful ping, but almost nothing from a failed ping. In this example, the last condition is the true one, and there’s no problem whatsoever. You simply can’t ping Microsoft.com, because their server ignores the requests.
For that reason, it’s good to remember a destination that does return pings. I tend to use northrup.org, google.com, and yahoo.com because they reply to pings, they have servers everywhere, and they’ve never been offline when I’ve tested them.
Ping has several options, and you can view them all by running ping –? at a command prompt. The only one I use on a regular basis is –t, which keeps pinging a destination forever until you stop it by pressing Ctrl+C. For example, you can run the following command:
ping –t 8.8.8.8The constant stream of pings is a good way to temporarily monitor your Internet connection and latency. For example, if you’re waiting for your Internet connection to come back online, run that command and wait. Once you start seeing replies, your connection is back online. If you’re having latency problems, you can run that command and see when the latency increases or decreases.
Windows 8.1 includes a more powerful, if not as famous, tool: PathPing. PathPing sends separate ping requests to every router between your PC and the destination you specify, and it does this for several minutes to give you a better understanding of your current network conditions. PathPing, and network geeks, call the interconnected routers that forward communications between two points “hops.”
Take a look at this example:
pathping microsoft.com
Tracing route to microsoft.com [64.4.11.37]
over a maximum of 30 hops:
0 Win8Rules [192.168.2.7]
1 192.168.2.1
2 10.112.192.1
3 static-206-53-95-130.cpe.contoso.com [206.53.95.130]
4 static-206-53-95-3.cpe.contoso.com [206.53.95.3]
5 ten10-4.ur1.rochester.nh.contoso.com [65.175.142.201]
6 TBD-65-175-128-2.contoso.com [65.175.128.2]
7 te0-6-0-2.ccr21.bos01.atlas.fabrikam.com [38.122.126.73]
8 te0-0-0-3.mpd21.jfk02.atlas.fabrikam.com [154.54.6.2]
9 te0-5-0-1.ccr21.jfk07.atlas.fabrikam.com [154.54.80.182]
10 * * *
Computing statistics for 225 seconds...Line 0 indicates that PathPing was able to communicate with my own PC, named Win8Rules. While it’s a bad sign if you talk to yourself, it’s a good sign when your PC is able to.
Line 1, 192.168.2.1, is my router, also known as my default gateway. The first hop outside your own PC is always your default gateway. If that responds correctly, you know your home network is working properly, and any problems you’re having are either between your house and your ISP or on the Internet.
Line 2, 10.112.192.1, is the router my ISP uses to connect my home to their network. The second hop outside your own PC should always belong to your ISP. If that’s the first hop that fails, then your ISP is having a problem, and you should call them.
The last hop in this output, line 10, has three asterisks (*). This indicates that the three requests PathPing sent to it didn’t get returned. As we learned earlier, Microsoft.com doesn’t reply to pings. However, because lines 0-9 worked, we know our Internet connection is working properly.
After a few minutes, PathPing will compute performance statistics and display them to you:
Source to Here This Node/Link
Hop RTT Lost/Sent = Pct Lost/Sent = Pct Address
0 Win8Rules [192.168.2.7]
0/ 100 = 0% |
1 3ms 0/ 100 = 0% 0/ 100 = 0% 192.168.2.1
0/ 100 = 0% |
2 20ms 0/ 100 = 0% 0/ 100 = 0% 10.112.192.1
0/ 100 = 0% |
3 31ms 0/ 100 = 0% 0/ 100 = 0% static-206-53-95-130.cpe.contoso.com [206.53.95.130]
0/ 100 = 0% |
4 27ms 0/ 100 = 0% 0/ 100 = 0% static-206-53-95-3.cpe.contoso.com [206.53.95.3]
0/ 100 = 0% |
5 39ms 0/ 100 = 0% 0/ 100 = 0% ten10-4.ur1.rochester.nh.contoso.com [65.175.142.201]
0/ 100 = 0% |
6 37ms 0/ 100 = 0% 0/ 100 = 0% TBD-65-175-128-2.contoso.com [65.175.128.2]
0/ 100 = 0% |
7 27ms 0/ 100 = 0% 0/ 100 = 0% te0-6-0-2.ccr21.fabrikam.com [38.122.126.73]
0/ 100 = 0% |
8 41ms 0/ 100 = 0% 0/ 100 = 0% te0-0-0-3.atlas.fabrikam.com [154.54.6.2]
0/ 100 = 0% |
9 41ms 0/ 100 = 0% 0/ 100 = 0% te0-5-0-1.atlas.fabrikam.com [154.54.80.182]
Trace complete.The performance output is more difficult to read. Each numbered hop corresponds to the hops listed in the previous output.
The second column, RTT, is the average round trip time, which measures the latency. This gives you a tremendous amount of information about the performance of the network between you and the destination. You can tell roughly how much latency each hop is adding to your total round trip time. In this case, my home router is adding 3 ms of latency, and most of the rest of the latency is occurring in the second and third hops—on my ISP’s own network. The latency is still fairly small, however. If that RTT number were more than 250 ms, I might call to complain.
Notice that the RTT for hop 7 is actually lower than for hop 6. The RTTs aren’t particularly accurate; they’re only useful as a general gauge. Latency varies quite a bit on every network. Additionally, some routers don’t respond to pings immediately, which can make their RTT higher than the true latency.
If your local network is working but your Internet connection is down, PathPing output will resemble the following:
Tracing route to microsoft.com [64.4.11.37] over a maximum of 30 hops: 0 Win8Rules [192.168.2.7] 1 192.168.2.1 reports: Destination host unreachable
As you can see, PathPing was able to communicate with the local PC and your local router, but it couldn’t get past your router. The problem could be your router configuration, but it’s probably your ISP. Go ahead and give your ISP a call. If you’re the patient type, you might just wait for them to detect the problem and fix it—they probably already know about the issue, because most ISPs monitor that type of problem very closely.
Both Ping and PathPing have a serious weakness: not every host replies to pings. For example, Ping isn’t a good way to determine if www.microsoft.com is working because www.microsoft.com never responds to pings, whether it’s working or not.
PortQry is a better way to determine whether a specific server on the Internet is working. Unfortunately, it’s not included with Windows. However, you can download PortQry from http://www.microsoft.com/en-us/download/confirmation.aspx?id=17148 and save it to a folder on your local computer.
Like Ping and PathPing, PortQry is a command-line tool. Before you can run the command, you should change the command prompt’s current folder by running the command CD. For example, if you extracted the tool to its default folder of C:PortQryV2, you would run the command cd PortQryV2.
Once you’ve switched to the appropriate folder, run the command using the –n parameter to specify a name in the format portqry –n <hostname>.
The following example shows that the server at Microsoft.com is responding:
portqry -n microsoft.com
Querying target system called:
microsoft.com
Attempting to resolve name to IP address...
Name resolved to 65.55.58.201
querying...
TCP port 80 (http service): LISTENINGWe know the web server is responding because the last line shows LISTENING, which indicates that it’s listening for incoming connections. That doesn’t tell us that the web server software is working properly, but the operating system is listening for connections.
If you only specify a name, PortQry assumes you want to check for a working web server. There are other types of servers on the Internet, such as mail servers. You can add the –e parameter to PortQry to check a different port number.
For example, if you want to check whether a mail server is running, use TCP port 25 (for an SMTP server). The following command verifies that the Microsoft SMTP server is listening for connections on port 25, and even shows you the message the server sends upon an initial connection:
portqry -n mail.messaging.microsoft.com -e 25
Querying target system called:
mail.messaging.microsoft.com
Attempting to resolve name to IP address...
Name resolved to 216.32.180.22
querying...
TCP port 25 (smtp service): LISTENING
Data returned from port:
220 VA3EHSMHS031.bigfish.com Microsoft ESMTP MAIL Service ready at Wed, 22 Aug 2012 20:07:24 +0000While tools like Ping, PathPing, and PortQry are useful for troubleshooting network connectivity problems, many network problems impact only a single application. When network problems occur at the application layer, you can analyze and isolate the problem with Network Monitor.
Network Monitor is a protocol analyzer, which is a tool network administrators use to examine individual network packets. Besides being a useful troubleshooting tool, it’s really fun to peer inside your network to see how different apps communicate.
You can install Network Monitor for free from Microsoft.com. The current version is 3.4 and is available at http://www.microsoft.com/en-us/download/details.aspx?id=4865, but the program is updated regularly, so search the Internet for “download network monitor” to be sure you get the latest version.
Once you install Network Monitor, you need to log out and then log in before you can start it. After starting Network Monitor, begin recording by clicking the New Capture button and then clicking Start. As shown in Figure 23-6, you’ll discover that Windows is constantly communicating on the network even when you don’t have any apps running.
To use Network Monitor to analyze an app’s communications, start a capture and then perform an action in an app. Then, return to Network Monitor and click Stop.
With the capture made, you can take your time and analyze the communications that occurred while you were recording. In the left pane, select the process name that you want to analyze. This isn’t the same as the app name, but it’s usually pretty obvious. For example, Internet Explorer is IExplore.exe.
Select individual frames in the Frame Summary pane, and view their details in the Frame Details pane. You can close the Hex Details and Display Filter panes to save screen space.
Figure 23-7 shows Network Monitor analyzing HTTP communications from Internet Explorer retrieving the default page of Microsoft.com. As you can see, Internet Explorer sent the HTTP command GET /en-us/default.aspx. The Frame Details pane also reveals the source and destination IP addresses and port numbers.
Figure 23-8 shows the response from the Microsoft.com web server, an HTTP Ok message, along with the compressed contents of the webpage. Examining the frames recorded by Network Monitor, you can see that retrieving the webpage required dozens of individual requests to several different locations on the Internet, which is typical of modern webpages.
This example shows a healthy web request. In a troubleshooting scenario, you’d probably be examining an app that wasn’t working properly. Examining individual packets can reveal that the app attempts to communicate with a server that isn’t responding, that the client’s request is failing an authentication attempt, or that the server requires the client to be upgraded.
Network Monitor is not a simple tool to use. However, when an app is experiencing problems communicating across a network, it’s the best way to examine every detail of the communications.
There’s no one process that you can follow to troubleshoot all network problems. However, this straightforward process can isolate or solve most common home networking issues. After each step, test to see if your network is working again, and stop if your problem is solved.
Note
Troubleshooting a failed Internet connection Watch the video at http://aka.ms/WinIO/homenetwork.
Restart your modem, router, switches, wireless access points, and PCs in that order.
Test the Internet from different PCs or network devices. If the network is offline for all of them, continue with the next step. If some devices can connect and others cannot, jump to step 6.
Open a command prompt and run ipconfig. Identify the default gateway. Then, run the command ping <default_gateway>. For example, you might run ping 192.168.1.1. If you receive replies, the problem is probably with your modem or your ISP’s network. Call your ISP for technical support and stop working through this process. If you do not receive replies from ping, continue on to the next step.
If you performed the previous step from a wireless PC, connect it to a wired network if you can, or use a PC that is wired to your router. Then, repeat the test by running ping <default_gateway>. If it fails again, your router is either misconfigured or failed; if you’ve recently changed the configuration, change it back. If you receive replies to your ping, continue to the next step.
You now know that your problem is specific to your wireless network. If you’ve recently changed the configuration, change it back. If you haven’t changed the configuration and it previously worked properly, contact your wireless access point’s technical support or seek help from the Internet, as described in Chapter 8. You can stop working through this process.
You now know that the problem is specific to a single PC. Follow these steps:
If you’ve recently changed that PC’s configuration, change it back.
If the problem persists, verify that the IP settings are configured to Obtain An IP Address Automatically and Obtain DNS Server Address Automatically, as described in Chapter 21.
If the problem persists, run Device Manager from Settings, expand Network Adapters, right-click your network adapter, and then click Properties. If available, click Roll Back Driver. If not, use another PC to check the Internet for an updated driver and install it. You can use a USB flash drive or memory card to transfer it to the PC without an Internet connection.
If the problem persists, it’s likely that your network adapter has failed. Attempt to connect a different network adapter to the computer, such as a USB network adapter. If that solves the problem, you’ve confirmed that the network adapter has failed. Contact your PC’s technical support to have it replaced if it’s under warranty.
If the problem persists, there is an incompatibility between your PC and your router or wireless access point. For example, the router or wireless access point might be configured to block communications from that PC. Reset your router or wireless access point to its default settings (in particular, turn off any vendor-specific performance enhancements) and attempt to reconnect.
If the problem persists, seek help for additional troubleshooting, as described in Chapter 21.
At times, your network won’t completely fail. Instead, it will slowly limp along. Pages will seem to take forever to load, file transfers will take longer than they should, or video streaming will repeatedly pause while it buffers.
Network performance problems can be introduced in two places: your Internet connection (which your ISP manages) or your home network (which you manage). The sections that follow describe how to measure and optimize the performance of both parts of your Internet connection.
Measuring Internet performance is simple; visit http://speedtest.net/. As shown in Figure 23-9, the website measures your performance by sending data to and from your PC. In my experience, it’s quick and accurate.
Of course, unless you have your PC connected directly to your modem, it’s not really measuring just your Internet performance. Instead, it’s measuring the combined performance of both your home network and your Internet connection, and whichever is slower will limit your performance. In the IT world, we refer to this as the performance bottleneck.
To really test your Internet connection, connect a PC directly to your router with wired Ethernet. If the performance while connected to wired Ethernet is significantly better than the performance while connected to your wireless network, then your wireless network is limiting the connection of your Internet. For tips on getting the best performance out of your wireless network, read Chapter 21.
Your Internet performance is likely to vary throughout the day. Typically, after work hours on weekdays are the busiest times for residential ISPs, and as a result, you’ll see the lowest speeds at those times. Unfortunately, those are also the times you’re likely to be downloading files and streaming video.
There’s probably nothing you personally can do to improve the performance of your Internet connection. You can try restarting your modem and router, but it probably won’t help. Other than that, you can call your ISP to complain that your network performance doesn’t match what they advertise, but they’ll probably just tell you that your contract states that your performance will vary.
Most home users won’t ever need to worry about the performance of their local network, because all their communications travel between their PC and the Internet. Local network performance is only important to those of us who transfer large files between two computers or who use tools such as Remote Desktop to remotely control a PC on their home network.
If you do care about local network performance and your network seems to be slow, the first step is to measure the network performance so you can determine whether the network is performing like it’s supposed to. In other words, if your 100 Mbps wired network seems slow, but it’s actually performing near the practical limit of 60 Mbps, then your network is doing the best it can, and there’s nothing you can do to troubleshoot it. Instead, you would need to upgrade your network. Network design is discussed in Chapter 21.
If you have two PCs connected to your network, install LAN Speed Test v1.1.7 (the free version, available at http://www.totusoft.com/lanspeed.html) on the PC that seems slow. Click the button next to Folder Or Server IP field, and browse to a folder on a remote computer (for example, within Homegroup). Then, click Start Test and click OK.
Figure 23-10 shows the results on my home network, across both wired Ethernet and powerline network adapters. The only field you need to look at is Mbps. In Figure 23-10, the writing speed is 497 Mbps, and the reading speed is 576 Mbps.
Now that you know how fast your local network is, how can you determine whether it’s performing as it should be, or whether there’s a problem? Table 23-1 shows typical throughputs for different types of home networks. These aren’t the stated bandwidth, or even the theoretical maximums, but rather the practical throughput that you can expect in a real-world environment. With wireless networks, of course, distance, obstacles, and interference can drastically reduce the maximum throughput.
Table 23-1. Practical speeds of different home networks
Network type | Speed |
|---|---|
802.11a | 25 Mbps |
802.11b | 5 Mbps |
802.11g (with 802.11b compatibility) | 18 Mbps |
802.11g (native mode) | 25 Mbps |
802.11n (with 802.11b/g compatibility) | 80 Mbps |
802.11n (native mode) | 125 Mbps |
100 Mbps wired Ethernet | 65 Mbps |
1000 Mbps (gigabit) wired Ethernet | 650 Mbps |
Powerline networking rated 85 Mbps | .5-10 Mbps |
Powerline networking rated 200 Mbps | 5-150 Mbps |
Powerline networking rated 500 Mbps | 30-200 Mbps |
To optimize your network, follow the network design guidelines described in Chapter 21.
Inside OUT: The wrong ways to test network performance
I’ve talked to many people confused about network performance because they used invalid metrics. It seems like you could trust the network hardware manufacturers, or even Windows, but you have to completely disregard the stated maximum speed of a link, especially with wireless connections. That includes the description Windows provides you. Just because Windows says your network link is 100 Mbps doesn’t mean it’s actually achievable.
Second, transferring large files isn’t a good way to measure network performance. You can copy files between computers, and Windows will show you the transfer speed. For example, Figure 23-11 shows a transfer speed of 9.1 MB/s. Since there are 8 megabits (Mb) in one megabyte (MB), this transfer speed converts to about 73 Mbps. That might be the maximum throughput of the network, but it also might be the maximum read speed of the source’s hard drive, or the maximum write speed of the destination’s hard drive, factoring out any competing input/output from other apps.
