Quality of Service in Networking
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| Fig 1: Quality of Service in Networking |
Explanation to understand QoS
what exactly is QoS and can you monitor it let's start with what it is let's suppose you want to take a bus to the train station where you'll continue your journey by train so you get on a bus headed for the station after a short time the bus hits a traffic jam that was caused by an accident uh-oh you're going to miss your train if only you had a separate lane on the road that only the bus could use well in many modern cities this is a reality buses have their own lane and they can keep their timetable regardless of the traffic on the roads buses are prioritized over other road users QoS works in exactly this way the road corresponds to the bandwidth of your data connection and the bus corresponds to a prioritized data packet such as is used for a voice or video connection QoS is like giving these data packets their own bus lane to guarantee the quality of the service even during peak traffic periods quality of service technologies are designed to make IP networks real-time capable and ensure that important applications functions smoothly.
QoS Principles
There are essentially two ways to apply QoS principles either through integrated services or “intserv” where you give certain data traffic a priority or through differentiated services called “diffserv” where you mark specific data packets as having a high priority so how do we ensure QoS we've established that QoS is indispensable for real-time applications like voice over IP but it can also play an important role in other applications like enterprise resource planning systems many companies often have branch offices outside large cities that are not always connected to the head office by a fast internet connection the data must be sent and received through this connection it is therefore practical to prior the data traffic of the erp system over other traffic's such as HTTP in order to prevent interruptions in the connection so QRS is clearly vital and while setting your QoS policies is one part of the puzzle another very important part of it is monitoring it because it's only through monitoring your network that you can know what here OS policies and protocols to implement your approach to monitoring should be twofold.
Monitoring
Firstly monitor your network before implementing QoS this will give you an idea of where potential bottlenecks or issues can occur and you can plan necessary upgrades the data will also inform what QoS policies you need to implement secondly you should monitor your network after implementing QoS this will ensure that your policies are working and that you don't miss problems that might arise so what exactly do you need to monitor QRS well you can't monitor cures directly but here are four network metrics that should inform your QoS decisions delay or latency this is the length of time it takes for a packet to get from sender to the receiver long time delays in the delivery of voice over IP data means poorer audio and video quality plus delays and discussions make it difficult to communicate remotely jitter jitter measures the variation of delay that is how consistent is the delay do all packets have a similar delay or low jitter or are some packets fast and others slow high Jitter if there is high jitter voice and video streaming will be very choppy packet loss packets can get lost arrive as duplicates or arrive in the wrong order this could happen in cases of network overloads poorly performing devices or hardware and software errors packet loss can directly impact the quality of a service.
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