1 Simplify VoIP Network Setup and Troubleshooting with NetTool VoIP Introduction As businesses search for new ways to cut costs and increase efficiency, they are moving their phone systems to VoIP (voice over Internet protocol) in increasing numbers. In fact, a great many businesses these days, whether large or small, are either thinking about deploying VoIP, are in the process of deploying it, or have already done so. For example, In-Stat/MDR reports that the overall percentage of companies using VoIP communications quadrupled between 2003 and 2004, growing from 3 percent to 12 percent. 1 And Gartner predicts that voice and data traffic will increasingly be combined onto a single converged LAN network, with IP telephony applications eventually completely replacing circuit-switched PBX voice systems. It is now not a question of if IP telephony will be adopted but when, says Gartner. 2 Gartner also predicts that by 2010, 40 percent of companies will have completed the convergence of their entire voice and data network onto a single network, and more than 95 percent of large and midsized companies will have started the convergence process. 3 By setting up VoIP networks, companies can not only potentially save money on their long-distance calls, but they can also achieve significant productivity gains through combining other applications with telephony. For example, a company might set up a call center application to automatically display a customer s record on the representative s screen when the customer calls in. Companies can realize additional cost savings by leveraging a single wiring infrastructure to carry both voice and data instead of setting up two separate wiring systems and by using a single IT staff group to manage both voice and data. IT departments contemplating a move to VoIP must realize, however, that VoIP phone systems are an extremely mission-critical application one that must perform flawlessly or face the wrath of end users. While end users will normally put up with some minor glitches when a new IT system is deployed, that is not the case with VoIP. If end users pick up the phone and cannot get a dial tone or cannot connect to the number they are dialing, or cannot interpret what a caller is saying due to poor voice quality their ability to conduct business will be seriously affected, and companies will find that unacceptable. Therefore, in planning a move to VoIP, you will want to set the bar for acceptable quality much higher than with most IT applications. In order to obtain management s approval and end-user acceptance, you will need to be able to deliver great quality and rock-solid performance from the moment the system is turned on. Fortunately, NetTool VoIP from Fluke Networks can help. You can use this portable test and troubleshooting product before deploying VoIP to determine whether the network infrastructure has the necessary power and connectivity and is properly configured to support VoIP. You can use the tool during deployment to make sure that the IP phones will be up and running when users come to work the next day and need to make phone calls. And you can use it after deployment to troubleshoot any problems that arise. This application note begins by explaining how a portable test device can complement a VoIP monitoring system that uses remote software agents for network testing and troubleshooting. It then explains what NetTool VoIP is and shows how you can use it during the planning stages for VoIP, during VoIP deployment, and after deployment to keep your VoIP system running smoothly. NetTool VoIP Simplifies network setup and troubleshooting
2 The case for a portable VoIP network tester There is more to a VoIP phone network than just the phone. The key elements of a VoIP network are switches (those that supply power over the Ethernet cabling becoming more popular), DHCP servers, TFTP servers, DNS servers, call servers and the IP phones. The phone resides on the edge of the network on the user s desk while the other elements reside in the core of the network in an equipment room or data center. Today you have the choice of two tools to help you in the deployment and maintenance of your VoIP network: portable network testers and centralized management systems. Each choice has its strengths and weaknesses. You carry a portable network tester, typically a ruggedized handheld device, to the location where you want to test your network. A centralized management system is loaded onto a networked PC and gathers information about the VoIP network via remote software and hardware agents. The portable network tester is best suited to the task of troubleshooting at the network edge while centralized systems are better at resolving issues within the core. Network management vendors are increasingly pushing the use of remote software agents and centralized information analysis for network testing and troubleshooting. While this approach does have the advantage of reducing mobile staff requirements, a strong case can be made for also having a portable tool that frontline technicians can use to troubleshoot IP phone problems at the desktop. A portable troubleshooting tool offers several benefits: It simplifies the data that needs to be interpreted, making it easy for frontline technicians to use. Because the portable tester can perform tests at the IP phone s location, it can distinguish between problems in the phone itself and problems in the IP path, such as a WAN link that is down. Testing at the end user s location can provide more helpful troubleshooting information than active testing from a remote location, because the active test may not test the segment of the network that is causing the problem. In addition, tests performed at the end user s location will not be affected by other network factors, such as congestion or WAN delays. If the remote troubleshooting application requires a remote agent to be installed on the IP phone, it can increase the complexity and cost of the IP phone hardware. There are some problems that simply cannot be diagnosed remotely for example, a bad patch cable or a loose wire in the wall jack. VoIP deployment
3 For all these reasons, a portable test device connected at the end user s location is often the easiest, most accurate, and least expensive way to test and troubleshoot IP phones. For example, a portable test tool can: Take measurements that have to be made in line for instance, testing for an available power supply, such as Power over Ethernet (PoE) voltage, or checking for authentication or cabling problems. Observe the IP phone s behavior directly, without worrying about the effects of routers, switches, and other network elements. Test and troubleshoot regardless of whether there are any failures elsewhere in the network and regardless of the availability of network bandwidth. In addition, because a portable test device generally costs about one-tenth the price of a central management system, organizations can afford to equip multiple individuals with these handy tools. Providing frontline technicians with a personal tool they can take to a user s desktop enables organizations to quickly and cost-effectively determine whether desktop issues are contributing to a problem before having a Level 2 or Level 3 technician go to the time and expense of performing an in-depth analysis of the entire network infrastructure. What is NetTool VoIP? NetTool VoIP is designed to support converged networks that is, networks that carry both voice and data. As the world s only handheld networking tool for VoIP troubleshooting, NetTool VoIP is smaller, lighter in weight, easier to use, and less expensive than traditional troubleshooting tools. Instead of trying to troubleshoot a problem remotely, you can take NetTool VoIP to the exact location of the problem, where you can perform inline testing and troubleshooting directly on the IP phone without worrying about the effects of network components on test results or the availability of network bandwidth. What s more, NetTool VoIP enables you to see directly into the workings of the IP phone an area where there is currently little visibility. For all these reasons, it is the ideal tool for troubleshooting VoIP issues at the edge of the network. NetTool VoIP offers the full capabilities of existing tools for LAN deployment and troubleshooting, including ping tests, tests for speed and duplex settings, and tests for PoE. It can tell you if the source of a problem is in the phone, the switch, cabling, or the network and it can identify network problems from Layer 1 all the way to Layer 7. It can also monitor the VoIP signaling and RTP (real-time transport protocol) stream of voice packets; tell you if the IP phone is in the correct VLAN (Virtual LAN); and log a variety of per-call statistics, including events, jitter (the variation in the arrival time of packets compared to the expected arrival time as measured at the receiver), packet loss, call setup time, and call duration. In short, NetTool VoIP is an ideal way to quickly diagnose a broad range of problems before going to the time and expense of in-depth network testing. Key advantages of NetTool VoIP include: Speed. Because NetTool VoIP requires very little setup or configuration, it is the fastest test tool available for troubleshooting IP phones. It boots up instantly and can quickly deliver the information you are looking for in a fraction of the time required by other solutions. Comprehensive testing of IP phones. NetTool VoIP is a great complement to a VoIP monitoring solution because it can perform many measurements that a monitoring system cannot. For example, it can tell you if the IP phone is not connected to the switch, if the switch port is misconfigured, or if the IP phone is not getting power. No need to reconfigure the network. NetTool VoIP can be used without having to configure the network in any particular way for example, to set up port mirroring. Since you are testing the device directly, the network setup is not a factor. This makes NetTool VoIP faster and less expensive to use than a protocol analyzer and it enables you to save your protocol analyzer for higher-end troubleshooting tasks, such as finding sequence errors in packets or verifying if switch ports are timing out. Ease of use. NetTool VoIP is intuitive and easy to use. For example, it automatically filters the packets to deliver just the ones you need to troubleshoot VoIP as opposed to a protocol analyzer, which captures all packets it finds between the switch and the end of the network. And because it requires no specialized expertise or training, frontline technicians can begin using NetTool VoIP immediately.
4 Testing beyond the IP phone. NetTool VoIP is not limited to testing IP phones: you can also use it for a broad range of other test purposes, including testing PCs, switch ports, IP-based cameras, and network access points. For all these reasons, NetTool VoIP enables frontline technicians to solve many of the problems that previously had to be escalated to network engineers. It also eliminates the time wasted by passing problems back and forth between the phone technicians and network technicians: with NetTool VoIP, a single technician can easily isolate a problem to a specific source. Using NetTool VoIP Figure 1 illustrates four different testing configurations for NetTool VoIP: connecting NetTool VoIP directly to the switch; connecting NetTool VoIP between the IP phone and the switch; connecting NetTool VoIP to the IP phone, which in turn is connected to the switch; and connecting NetTool VoIP between the PC and the IP phone. Together, these four configurations enable you to test, monitor, and troubleshoot different aspects of your network. 1 The remainder of this application note explains how you can use NetTool VoIP at three different stages of the VoIP lifecycle: before deploying VoIP, to verify that your network is properly configured for VoIP and has the necessary power and connectivity; during deployment, to verify that each VoIP phone is working properly; and after deployment, to troubleshoot any VoIP problems that crop up. It also briefly touches on using NetTool VoIP between the phone s PC port and the PC to troubleshoot PC operations. Getting ready to deploy VoIP You can save time and prevent later difficulties by making sure your network is ready to support VoIP before you actually begin deployment, and NetTool VoIP can help you with this task. By verifying in advance that key elements of your network infrastructure are VoIP-ready, you can avoid unscheduled overtime when the VoIP systems are being installed and you can also ensure a smoother, more predictable deployment process. The key steps to take before deployment are: 1. Test for drop activity. The first step is to verify the drop is active that is, that it is carrying data. Even before the IP phone is present, you can use NetTool VoIP to verify that the wall jack, cable, patch cable, and switch ports are all functional. You can verify the speed, duplex, VLAN and switch port associated with the drop. For this test, you connect NetTool VoIP directly to the switch, as shown in Figure Figure 1: VoIP testing configurations 1. NetTool to switch 2. IP phone to NetTool to switch 3. NetTool to IP phone to switch 4. PC to NetTool to IP phone to switch 4 Figure 2: Connecting NetTool VoIP directly to the switch enables you to verify that the drop is active. 2. Test for power. The next step is to add the IP phone and verify that power is being delivered to it. You will need the IP phone for this step because the switch will not send power unless the IP phone solicits it. For this and subsequent tests, you will position NetTool VoIP between the IP phone and the switch, as shown in Figure 3.
5 With NetTool VoIP, you can: Verify that the right codec is being used. Verify that the VLAN ID and priority and the type of service bits are all correct. Figure 3: Connecting NetTool VoIP between the IP phone and the switch enables you to test for power availability and verify that network components are working properly. 3. Test DHCP and call server connectivity. You can use the same setup shown in Figure 3 to test Layers 1-3 in order to verify that the IP phone can: a. Acquire a DHCP (Dynamic Host Configuration Protocol) address from the DHCP server. b. Resolve key device names using DNS. c. Ping key network devices, such as routers, servers, and gateways. d. Download its image and configuration files using FTP. e. Register with its call server or gateway. 4. Test switch port configuration. You can also use the Figure 3 test configuration of the switch to confirm that you have the proper class of service and the appropriate VLAN configuration. 5. Test PoE voltage and polarity. Finally, you can use the same setup to identify the availability of power (i.e., PoE) and the voltage level and polarity on each pair to ensure that the network infrastructure is configured properly to send PoE to each phone. This step is particularly important if you are using third-party phones and/or third-party switches, to verify that they are compatible with each other. Once your network has passed all of these tests, you are ready to proceed with deployment. Deploying VoIP Because of the mission-critical nature of VoIP systems, it is important to make sure during the deployment process that IP phones are working correctly you do not want to discover problems the next day, when users come in and try to use the system. Again, there are several steps you can take during deployment to check for possible problems, and NetTool VoIP can help you with each of them. In fact, NetTool VoIP is the only tool that enables you to directly monitor transmissions between the IP phone and the VoIP network, so you can see exactly what is going on. Ensure that the IP phone is using the correct call server(s). Monitor and measure call setup time to determine if it is within the acceptable range. Verify that the voice quality of the call is satisfactory. For these tests, you again connect NetTool VoIP between the IP phone and the switch, as shown in Figure 3, above. This strategic inline configuration allows you to see what the IP phone is actually sending and receiving, unmodified by the network in any way. It also allows for direct tracking of call setup between the IP phone and call server, to verify that the two devices are interacting properly. Some specific tests that are helpful to perform at this point include: 1. Test for jitter and dropped packets. You can use NetTool VoIP to measure voice traffic for such problems as jitter and dropped packets. With these problems, it is not so much the existence of the events that you need to be concerned about, but rather the degree to which they occur and whether they fall within acceptable levels for your organization. For example, while an occasional dropped packet may not be audibly detectable, a drop burst that is greater than 100 ms can definitely have a negative effect on call quality. 2. Test phone s PC port. Because most office cubicles have only one drop, for employees to be able to use both an IP phone and a PC you have to plug the network cable into one port on the IP phone and the PC into the other. You can use NetTool VoIP in the configuration shown in Figure 4, below, to verify that the IP phone s PC port is configured correctly, that the PC can acquire a DHCP address, and that it can ping network resources. Figure 4: You can use NetTool VoIP to verify that the IP phone s PC port is working properly.
6 Troubleshooting VoIP problems Once you have your VoIP system deployed, you can use NetTool VoIP to troubleshoot any problems that occur when a phone is first connected to the VoIP network, as well as for problems that occur later, during VoIP phone calls. The setup for troubleshooting both types of problems is the same as that shown in Figure 3, on the previous page. When the IP phone is first connected to the VoIP network The normal sequence when an IP phone is first connected to the VoIP network is that the IP phone: 1. Solicits and receives power from the switch. 2. Broadcasts a message asking for its IP address to which the DHCP server responds by assigning it an IP address, as well as providing it with the addresses of the default router, DNS and TFTP (Trivial File Transfer Protocol) server. 3. Boots up and requests the operating image and configuration files from the TFTP server. These files provide the operating firmware as well as default and custom configurations, such as ring tones and screen background. 4. Registers to the call server and receives an acknowledgement from it. It will then communicate with that call server whenever anything happens when the user goes off hook, presses a button, and so forth. Some of the problems that can occur at this stage are: There is no voltage on the line, so the IP phone receives no power. The IP phone cannot communicate with the DHCP server. The IP phone either is either given invalid IP addresses for the TFTP and call servers or is not given their addresses at all. NetTool VoIP can help you troubleshoot each of these problems. Here are some easy troubleshooting steps you can take: 1. Blank screen, no dial tone. If the screen is blank and there is no dial tone, you can use NetTool VoIP to measure the voltage on the line. This step will tell you if the IP phone is receiving power. Your next steps are: a. No voltage. If there is no voltage, it could be a cabling problem, a switch port configuration problem or a bad switch port. At this point, your next step is to use NetTool VoIP to test the cable in order to verify if the problem is in the cable. If the cable checks out fine, then you can use NetTool VoIP to see if the switch port is properly configured. If it is not, then the switch port needs to be reconfigured. b. Voltage present. If voltage is present, the problem could be with the DHCP server (see test 2, below). 2. No response from DHCP server. If you see a request going out to the DHCP server but no response coming back, the DHCP server might be directing the IP phone to use the wrong VLAN. You can use NetTool VoIP to determine on which VLAN the IP packets are going out. If they are going out on the wrong VLAN, the switch port will have to be reconfigured. 3. No communication with TFTP server. If the IP phone is receiving a response from the DHCP server, the problem could be that it has the wrong IP address for the TFTP server. You can use NetTool VoIP to watch it attempt to contact the TFTP server and see if it gets a response or not. If it does not, you need to reconfigure either the DHCP server or the phone to set up the correct TFTP address. 4. No communication with call server. If the IP phone is getting power and a response from the DHCP and TFTP servers, then it most likely has an incorrect IP address for the call server. You can determine this by using NetTool VoIP to watch the IP phone attempt to contact the call server and see if it registers properly. If it does not, then you need to troubleshoot the call server. Problems that occur during VoIP phone calls During a normal VoIP phone call, the following sequence of events occurs: The IP phone contacts the call sever and sends it the phone number of the party you are calling. The call server validates the phone number, initiates the call, and indicates the call status (e.g., ringing). The called party answers, and the call server tells both IP phones (the calling phone and the receiving phone) which IP address and port numbers to use for streaming voice packets over RTP. Voice data streams in both directions until one party disconnects. The IP phone that disconnects notifies the call server, which in turn notifies the other IP phone to disconnect.
7 Some possible problems that can occur during VoIP calls include: There is no dial tone. The user can call out, but cannot receive calls. The user cannot make a particular type of call that he or she should be able to make (for example, long-distance calls, international calls, or conference calls). The phone does not ring when someone calls. The voice quality is poor. These are all areas where NetTool VoIP really shines: it is better than any other tool at helping you quickly diagnose the cause of such problems and fix them. Here are some easy troubleshooting steps you can take to isolate and fix each of the above problems: 1. No dial tone. If a user reports that there is no dial tone, you would go to the user s cubicle, hook up NetTool VoIP, pick up the phone, and go off hook. The next steps depend on whether you do or do not see an Off Hook signal going out: 2. No Off Hook signal. If you do not see an Off Hook signal going out, you have a bad phone and need to replace it. 3. No response to Off Hook signal. If you see an Off Hook signal going out but no response coming back, it could be a problem that the call server has with respect to that extension, or it could be that network packets are being filtered and blocked. Performing a ping test with NetTool VoIP will tell you which of these situations is the case. If it is the former, your next step is to troubleshoot the server; if it is the latter, your next step is to troubleshoot the network. 2. No incoming calls. When the user can make outgoing calls but cannot receive incoming calls, your first step is to verify that the IP phone has bidirectional communication. With NetTool VoIP hooked up, you would first verify that the IP phone can in fact make an outgoing call and then use another extension to call the user s phone and see if NetTool VoIP reports an incoming call. If it does, you have a bad IP phone and need to replace it. If it does not, you have a call server problem and need to troubleshoot that system. 3. Certain call types blocked. If the user has authorization to make a particular type of call (e.g., a long-distance, international, or conference call) but is unable to do so, you can troubleshoot the problem by attempting the call with NetTool VoIP connected inline and seeing what type of error tones are generated. If you get a fast busy signal, it is probably a call server problem. If the line is totally dead, with no error tones at all, it could be either a call server or a gateway problem or, more likely, both. Your next step in this case is to troubleshoot the call server or the gateway. 4. No ring for incoming calls. If the IP phone does not ring when a call comes in, you can place a call to that extension with NetTool VoIP connected inline and see if the call server sends a signal telling the IP phone to ring. If it does, the IP phone is bad and needs to be replaced. If it does not, the problem is with the call server. 5. Poor voice quality. If the voice quality is choppy, unintelligible, or otherwise hard to understand, you can have the user make a call with NetTool VoIP hooked up. NetTool VoIP will tell you if the connection is experiencing dropped packets or jitter. You can then compare the readings with your organization s quality standards to determine whether the readings are acceptable or not. a. Good readings. If the readings are all good, then it is not a network problem: it is either a bad IP phone or a call server or a gateway problem. If swapping out the IP phone does not solve the problem, the next step is to troubleshoot the call server or gateway. b. Bad readings. If the readings are bad, you need to troubleshoot the network to solve the jitter or packet loss problems. As noted above, it is not so much the existence of a jitter or packet-loss problem that you need to be concerned about, but rather whether the levels exceed acceptable parameters for your organization.
8 Troubleshooting PC problems NetTool VoIP is also helpful for troubleshooting PC problems. For these tests, you would connect NetTool VoIP inline between the IP phone s PC port and the PC, as shown in Figure 5. With this setup, you can see the link configuration and view the PC s interactions with the network, including the VLANs, IP addresses, servers, routers, and printers it is using. Figure 5. You can use NetTool VoIP inline between the PC and the IP phone to troubleshoot PC problems. Conclusion With increasing numbers of businesses moving to VoIP, and smooth-running IP phone systems being critical to a company s success, IT departments need to take the appropriate steps before, during, and after VoIP deployment to ensure trouble-free operation of their VoIP systems and the quick resolution of problems when they do occur. For companies that have not yet deployed VoIP systems, the IT department needs to make sure its network infrastructure has key capabilities in place before attempting deployment. During deployment, the IT department needs to verify that all IP phones are operating properly; and after deployment, the department needs a quick, costeffective way to troubleshoot and resolve any problems that arise. NetTool VoIP from Fluke Networks is the perfect test and troubleshooting tool for for the complete VoIP lifecycle. Not only is this handheld tool a fraction of the cost of a centralized troubleshooting system, but it also is easy for a frontline technician to use, is capable of performing important tests at the edge of your VoIP network that cannot be done with a centralized system, enables the technician to observe the IP phone s behavior directly, without interference from other network elements; and allows troubleshooting to take place regardless of failures elsewhere in the network or lack of bandwidth availability. Visit for more information about how NetTool VoIP can help your company simplify the move to VoIP and keep your VoIP system running smoothly. For more information on VoIP technology, visit 1 InStat, Business VoIP: An End-User s Perspective, Gartner, The Road to Internet Protocol Telephony, 3 January Gartner, Positions 2005: Voice and Data Will Converge Onto a Single Network via IP Telephony and Voice Over IP, 17 February NETWORKSUPERVISION Fluke Networks P.O. Box 777, Everett, WA USA Fluke Networks operates in more than 50 countries worldwide. To find your local office contact details, go to Fluke Corporation. All rights reserved. Printed in U.S.A. 8/ A-US-N Rev A