Voice over IP (VoIP) won’t go away. It is important that you understand how to buy services. The assumption that most Internet phone service providers make is that all networks are the same. When they sell you VoIP services, they rarely talk about your network. Honestly, most don’t care because it’s a numbers game. They understand that some customers are going to have a bad experience from having a network that does not support VoIP or an Internet connection that does not meet the requirements of VoIP services.
Before you give someone money for VoIP services, be sure to get a network assessment of their network to make sure that VoIP will work on your network and what the limits are. We will focus this article on one aspect of making VoIP work properly on your network: Quality of Service (QOS). QOS was defined by the ITU in 1994 to address network problems.
Your communications network may consist of a wireless router or even a port switching hub, but regardless of the type and model of network equipment, your network forms the backbone of your organization. Your network carries a multitude of applications and data, including high-quality video and delay-sensitive data such as real-time voice. Your network and Internet connection have limits on the amount of data it can process. I recently bought a flat screen smart TV that has a wireless interface to connect to my home network. The TV has several apps, including Netflix, for streaming movies directly to the TV. Bandwidth-intensive applications expand the network capabilities and resources of your network. Your networks must provide secure, predictable, measurable, and sometimes guaranteed services if you want to add VoIP services. This is done by achieving the required quality of service (QoS) by managing the parameters of delay, jitter, bandwidth, and packet loss on your network. QOS is simply a set of techniques for managing network resources.
Example one: you have two or three computers on your network with a 100MB connection. You have one or two wireless devices that have 54 megabit connections. Add two VoIP phones with 100 megabit connections and you have a total mandatory bandwidth of over 600 megabits, but your cable modem is only capable of delivering 5 megabits from your network to the Internet. Don’t panic, the good news is that only one device on your network can communicate with the internet modem at a time. The bad news is that only one device can communicate on your network at a time. If more than one device tries to communicate at the same time, a network collision condition is created. Your network is most likely a first-come, first-served network. This is fine for home use and some small businesses, but it is not a good means of managing a network.
Example two: the same devices as in example one, but better organized. First we have four networks or virtual local area networks or VLANs. VLAN number one is for the smart TV streaming Netflix, VLAN two is for my computers with a VLAN three is for all other wireless devices, and VLAN four is for all VoIP phones. All traffic is handled by a layer two (L2) switch. Let me quickly clarify something about switches. I know many people who think they have an L2 switch, but they don’t. The device that you think is a switch is a hub. It’s labeled a switch because the word hub has such a negative connotation. Hub manufacturers can get away with calling the switches because the hub can change the port speed from 10, 100, 1000 megabits. on a hub, only one device can talk, while on a switch, all devices can be configured to talk at the same time. On an L2 switch, traffic is handled by the switch when multiple devices are talking to the Internet modem at the same time. In this example, the L2 switch prioritizes voice traffic over wireless data, and wireless data is prioritized over computer-generated traffic, computer traffic takes priority over smart TV. If your amount of traffic exceeds the switch’s ability to send to switch L2, switch L2 will discard data based on configured priority parameters.
In example two, voice communication has the best chance of accessing the Internet or being sent to phones from the Internet. In example one, voice traffic would be delivered if the network was not being used by another device and application. Resources are exhausted, most of the computer generated traffic can be removed without much consequence because anything the other end does not receive will simply ask you to resend the data. But with voice, if you remove the third syllable from the fifth word, how do you forward that segment of speech in real time? You do not! The word becomes confusing and unrecognizable.
Never think that your network is too small for QOS. It is important to implement a QOS strategy before implementing QOS. If your Internet phone service provider can’t help you, find one that can.
