As each day passes, more and more businesses are implementing VoIP solutions. If you haven’t switched to VoIP just yet or you are looking for ways to maximize the quality of your current voice system, you should consider implementing Quality of Service solutions. QoS is a crucial part of any voice system because it has the ability to protect voice traffic on your network and guarantee good call quality. There are many facets of QoS, but I want to take the time to explain some of the most popular features.
Where does QoS belong on the network?
While it is true that a QoS policy can be applied anywhere within a network to guarantee call quality, it is usually most helpful when applied to WAN links. The reason for this is that LAN bandwidth is plentiful and cheap, but WAN bandwidth is finite and expensive. Most business networks do not suffer from a lack of LAN bandwidth, and the WAN links become the bottleneck in the network.
Types of Queuing Mechanisms
There are several different types of queuing structures designed to queue traffic in drastically different ways. I won’t get too detailed in these descriptions, but I do want to give a high-level overview of each type and how they should handle voice traffic.
Priority Queuing
Priority queuing has been around a while, and it is one of the older queuing systems. It basically divides network traffic into four categories: low, normal, medium, and high. For VoIP implementations, the voice traffic is assigned to the high priority traffic class. When a link using priority queuing sends traffic, it first checks the high priority queue, sends any traffic in that queue, and then proceeds to the next queue that has a lower priority. This process repeats as many times as needed until all traffic in the queues has been sent or the bandwidth is exhausted. This can become problematic, though, because the lower priority queues can become starved if there is too much traffic in the high priority queue. It is recommended that you utilize other modern queuing mechanisms.
Custom Queuing
This type of queuing is uses of 17 queues, with queues 1-16 being available for use by the user. Custom queuing is great because it is much more flexible than priority queuing. Each queue is essentially assigned a percentage of bandwidth. This is very customizable and allows you to reserve amounts of bandwidth for voice calls.
Weighted Fair Queuing
Weighted fair queuing automatically assigns priority to traffic based on the bandwidth that traffic consumes, and gives higher priority to the traffic that uses less bandwidth. Basically, this prevents large bandwidth applications from hogging all of the bandwidths. If for example, a user is downloading a large file on your network and hogging all of the bandwidths, WFQ would give priority to your lower bandwidth voice traffic and protect it from getting dropped. Also, WFQ can buffer and smooth out variations in delay (called jitter) to help smooth out voice calls.
These types of queuing mechanisms are only a subset of QoS features. However, this should help give you an understanding of how crucial it is to protect voice traffic on a modern network. Remember to consider a QoS strategy if you really want to get the most out of your voice system.
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