What is QoS?

Find out how QoS can aid your online gaming and stop VoIP calls from dropping out

Many routers (and modem/routers) offer a QoS feature, which is a handy way of ensuring that, for example, sending email and browsing the Web won't interfere with fast-paced online games or calls using Skype. QoS stands for 'Quality of Service' and it sorts out the traffic on your Internet connection to give priority to programs that need a constant stream of data.

It is particularly important for VoIP users that don't have a fixed phone line and make phone calls using their Internet connection. For example Skype users will benefit from QoS because the service needs voice and audio packets to be sent at the same time.

QoS guarantees that packets for a VoIP connection will not be delayed or dropped due to interference from other, lower priority traffic. It ensures you can make a phone call and not have it disconnected or interrupted due to overcrowding on your network.

Another application that can benefit from QoS is online gaming, where users need to download and upload data at a rapid rate. QoS can help prevent 'lag' caused by your network being saturated with non-game-related data packets.

If you just use the Internet for basic Web surfing purposes, you won't need to worry too much about QoS.

How does QoS work?

QoS regulates traffic on your network and it makes sure that important data packets reach their destination in the fastest time. QoS slows down unimportant packets but can't speed them up. This ensures that the most important packets (as determined by the user) reach their destination as quickly as possible. Since QoS cannot speed up a packet, it calculates how much upstream bandwidth you have (data going from your location to your Internet service provider) then divides this according to priority. QoS can't control your downstream data (data coming from your ISP to you).

Priority criteria of QoS will vary depending on the type of router you have. The Wi-Fi Multimedia (WMM) specification is supported by nearly every modern router and prioritises network traffic according to four access categories: from highest to lowest priority, these are voice, video, best effort and background. In order for this to work, however, WMM must be enabled in both the router's firmware and in the client's Wi-Fi adapter.

How do I use QoS?

For a step-by-step guide on how to configure QoS, read our comprehensive home networking guide .

Additional reporting by Michael Brown.

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Kevin Cheng

PC World
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