Quality of Service, or QoS, is a type of traffic shaping technology that enables you to determine the importance of different traffic on your network. In this context, we are primarily thinking about configuring QoS on the router for your local area network (LAN).
There are many different types of traffic being routed across our networks each day. These different types of traffic are known as network protocols . Some protocols are used to help computers find each other and know where to send traffic. Others are the protocols on top of which the services we use are built.
For example, the email service is built of top of a number of network protocols, such as POP, IMAP, SMTP and many others. Another example is the web sites that we visit, which are built on top of another protocol that you have probably heard of called HTTP. In the same way, VoIP calls also depend on a number of types of network protocol - SIP and RTP being the most well known examples.
When traffic is low, you won't experience any problems at all, but what happens when there's a bottleneck?
Well once the amount of available bandwidth is in short supply, then just like with a road system that is congested, the network traffic begins to queue. Some technologies cope with this queueing better than others. If the web page you are loading takes a second or two longer to load than normal, you probably won't even register the difference. However a VoIP call, particularly the audio part of the call, is very sensitive to this type of bottleneck. If packets take too long to route then you will notice this as poor audio quality and this is when configuring QoS can make a huge difference to your network.
Configuring QoS is mostly about limiting the bandwidth available to different devices and protocols. It's not particularly difficult to configure QoS once you understand a few basic principles. We'll walk you through these below.
Most routers will let you specify devices by IP address or IP subnet that you either want to limit or provide unrestricted access to. If you know that your provider has a fixed range of IP addresses, then you can whitelist those devices and be sure that traffic to and from those addresses is never limited.
In the same way, if you are using hardware phones, you could put all of your phones onto their own subnet and ensure that they get unrestricted access to the available bandwidth. If subnetting is not an option, then you could maintain a list of IPs for your phones that are whitelisted in the same way.
Set up some kind of monitoring and keep an eye on the users on your network. Some staff can be much bigger users of bandwidth than others. If a particular user is often downloading large files or watching a lot of video, then set them a bandwidth limit by IP address or MAC address and ensure that they cannot create a bottleneck that then impacts your voice calls.
It's always a good idea to whitelist or prioritise the VoIP protocols being used on your network. The standard VoIP protocols are SIP over UDP for signalling and RTP over UDP for audio/media, but there are many more out there including SIP over TCP or TLS, SRTP, ZRTP and many more.
Once you have determined the protocols in use for your VoIP service, then you can set about whitelisting them. For example, with standard SIP over UDP it's a good idea to whitelist UDP ports 5060-5080. With RTP over UDP you probably need to open up a large range of UDP ports - such as 10,000-20,000 or 50,000-60,000 - but you will need to talk to your SIP provider to confirm the range that they use.
As we mentioned briefly above, some types of traffic are relatively resilient to small delays. A good example of this is HTTP, where an HTTP page or other resource taking 500ms longer to load is barely noticeable. Other services you might want to limit might be things like video streaming (YouTube!), FTP and even the protocols used for file sharing applications like BitTorrent.
There have been many times we've been asked to investigate some call quality issues on a customer's network and upon investigation we've discovered a user on the network who is doing things on their PC that have not been approved by their manager!
Configuring QoS for your network can really make a difference, but obviously you need to be using a quality SIP provider in the first place. If you're not getting the kind of call quality that you want from your current provider, then please take a look at the products that we have available.
For those who already have on-site soft or hardware PBX equipment, you'll benefit from the fantastic performance and highly competitive call rates found in our SIP trunking solution.
For companies who want to out-source the running costs and management of their phone systems to the cloud, then our Cloud PBX will provide you with a state-of-the-art hosted PBX solution without any of the technical headaches that come with managing your own telephony infrastructure.