What Is QoS in Networking?

• QoS in Networking

  QoS in Networking

  Quality of Service (QoS) in networking is a traffic control process that helps companies adjust their overall network traffic based on the requirements of specific time-sensitive applications. It reduces common quality degradation issues such as packet loss, network jitter, and high latency within the network.
• How Does QoS Work?

  How Does QoS Work?

  Data transmitted over the network gets divided into packets containing control information such as network addresses (source and destination), protocol, sequence number, etc. QoS works by classifying and marking the packets based on their service type to determine which packets need priority over bandwidth within a network. Classification analyzes the packet header, which contains important instructions about the data within the packet. Traffic flow then gets marked to determine the packets with priority access. After traffic marking, networking devices (routers, switches, etc.) get configured to create queues for different packets per their priority. It ensures bandwidth is available for critical applications with high priority. Queueing and bandwidth management are two common QoS mechanisms used to handle packets per their classification.
• Why Is QoS Important? Advantages of QoS

  Why Is QoS Important? Advantages of QoS

  Network QoS plays a vital role in helping network administrators manage limited bandwidth within the network. QoS ensures the availability of real-time applications such as online video meetings, voice calls, and video conferencing. For instance, packet loss during voice or video communication directly impacts the quality of the video/call for end users. Outlined below are some of the advantages of QoS:

  • Improved User Experience: QoS works by identifying the traffic flow within the network and prioritizing it accordingly. It ensures critical applications run at their best and are available with fast response times for users.
  • Traffic Management: With QoS, network admins can better manage traffic flow by setting different bandwidths for different types of packets. This prioritization helps better drive traffic and avoid potential network congestion.
  • Cost Reduction: QoS enables better management of network resources. It reduces the need for organizations to upgrade network bandwidth and purchase additional network infrastructure.
  • Improved Security: QoS can detect abnormalities in the network. Network admins can block unwanted traffic and ensure application reliability by setting specific QoS security policies.
  • Reduced Packet Loss: Network congestion can lead to packet loss and hamper the performance of critical applications. QoS prioritization policies ensure packets get queued accordingly to avoid traffic jams within the network.
• Techniques and Best Practices

  Techniques and Best Practices

  Here are some QoS techniques organizations can use to ensure optimal application performance:

  • Classification and Marking: After identifying traffic, it must first be classified based on its type (e.g., voice traffic, video traffic, etc.). Classification involves examining the different fields of a packet. Traffic marking determines classification for the packet and sets its priority by changing the packet header. Traffic is commonly marked by two methods: Class of Service (CoS) and Differentiated Services Code Point (DSCP). In CoS, the data stream gets marked in layer 2 IP packet header, while in DSCP, the data stream is marked in layer 3.
  • Shaping: This process involves delaying the flow of specific network packets for less critical applications by limiting the bandwidth they can consume.
  • Queueing: It prioritizes certain packets for fast transmission of business-critical applications. Queues are buffers in networking devices that hold packets based on traffic classes. A packet with priority access gets assigned to a queue that can process it faster.
  • Resource Reservation: The Resource Reservation Protocol (RSVP) refers to a transport layer protocol that allows resources in the network to be reserved. It helps with the efficient utilization of network resources by delivering the desired level of QoS for the traffic flow.

  Best Practices

  • Before deploying QoS, perform a network assessment to understand the current network state, identify congestion and other network issues.
  • To simplify QoS management and maintenance, avoid unnecessarily configuring QoS and making it more complex.
  • To keep a check on queueing and packet assignment, assess the packet distribution ratio between available queues and the queues used by services.
  • Reduce complexity by configuring traffic prioritization through one type of priority: service-based priority or security policy priority.
• QoS Parameters

  QoS Parameters

  Listed below are the parameters organizations can use to measure QoS:

  • Packet Loss: Packet loss occurs when network devices drop incoming data packets due to heavy network overload. As packets fail to reach their destination, it results in packet loss.
  • Latency: The total time it takes for a packet to traverse the network from its source to destination is called latency. The lower the latency, the better. High latency can lead to unwanted bottlenecks in communication.
  • Jitter: Jitter occurs due to network congestion or variation in routing. It’s technically referred to as packet delay variation (PDV) as packets are delayed and arrive out of sequence.
  • Bandwidth: The maximum data transmitted across a network path at one time. QoS helps analyze what applications need more bandwidth than others.
• CBQoS Performance Views

  CBQoS Performance Views

  By implementing network QoS, network admins can help ensure business-critical applications have the highest priority in the network. Many organizations use automated QoS tools to monitor network issues and simplify QoS implementation. Some QoS tools support CBQoS, enabling network administrators to view network traffic segmented by Class of Service methods. Organizations can measure the effectiveness of CBQoS policies, manage network traffic by class, and analyze bandwidth usage for time-sensitive applications.

  These tools come with simple QoS controls and the ability to customize built-in reports and create new QoS or CBQoS reports. Network admins can also receive alerts about changes in application traffic. These tools also speed up troubleshooting by simple detection and mitigation of common network performance issues.