Quality of Service (QoS) in Computer Networks: Boosting Performance

Defined by the International Telecommunications Union (ITU) in 1994, Quality of Service (QoS) is alive and well in enterprise and service provider networks at its 30th birthday this year.

QoS is a cause for celebration since it allows IT teams to improve the performance of a computer network as the soaring use of voice, data, and video and lifeblood applications need flexible levels of service for users.

Recapping the Essentials

Quality of service tools use mechanisms or technologies that work on a network to control traffic and ensure the performance of crucial applications with limited network capacity. Rather than use complex load balancers, it enables organizations to adjust their overall network traffic by prioritizing specific high-performance applications.

At its core, quality of service in computer networks consists of bandwidth management and traffic prioritization. You can employ bandwidth management and traffic together or separately for any given type of traffic.

Using QoS in networking, organizations can optimize the performance of multiple applications on their network and gain visibility into the bit rate, delay, jitter, and packet rate of the network. They can engineer the traffic on their network and change the way that packets are routed to the internet or other networks to avoid crippling transmission delay. This also ensures that the organization achieves the expected service quality for applications and delivers expected user experiences.

The QoS techniques include traffic classification, traffic policing, traffic shaping, rate limiting, congestion management, and congestion avoidance. They address problems that arise in different network locations.

Understanding Packet Loss Prevention and Traffic Prioritization

Most IT managers understand the effects of packet loss. It hinders the overall user experience of communicating via email, accessing lifeblood business applications, and performing operational tasks. That's because network throughput declines, latency climbs, and users notice an underwhelming application experience. And the cost of adding tools to address problems becomes an added expense.

There are preventative measures that can be taken to minimize packet loss.

Quality of Service (QoS) Settings: QoS settings allow network resources to be organized to effectively control packet loss. This is useful in cases where the network transmits resource-intensive data such as voice and video. QoS settings drive more network traffic to accommodate resource-intensive data.

Traffic Prioritization: QoS is the key to the classification and traffic prioritization in the network. It enables you to create and set an end-to-end traffic priority policy designed to boost the control and throughput of crucial data. This is achieved by managing available bandwidth to let the highest priority traffic first.

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Categories of Quality-of-Service Technologies

Quality of service can support a variety of strategies to improve performance. In any scenario, different key technologies help enhance traffic flow in specific areas. Some common methodologies and associated technologies include classification, queuing, policing, marking, and congestion avoidance. Let’s look at some of these in more detail.

Traffic classification

With QoS, businesses can classify the type of IP packets or traffic, data, voice, or video into traffic classes. Traffic classes are groupings based on similarity.

Optimal Bandwidth Utilization

There are many preventative techniques you can use to optimize bandwidth utilization. N-able, a solutions provider to IT teams and MSPs, has identified several steps toward success with QoS. Palo Alto Networks also offers guidance for IT teams. Some of the steps to take to achieve results include:

Perform a network assessment. Conduct a network assessment that baselines your performance and its use to help set QoS policies.

Identify priority network traffic. Decide which network traffic types are of the highest priority.

Categorize latency-sensitive data flows. This includes voice and video conferencing. Next, identify data streams that are inessential.

Involve business leaders. It is of paramount importance that business leaders drive application categorization. They have insight into which applications are essential, while network administrators may only be able to speculate.

Remove non-essential data flows. Eliminating this traffic will mean QoS does not need to be used to drop this traffic when facing congestion.

Apply QoS classes. Once you have broken down your data flows into categories according to importance and latency requirements, you will need to assign these applications to one of several classes. A QoS class refers to the policy configuration performed on network routers and switches.

Less classes? QoS management is so complex because of the sheer amount of time and resources required to maintain each class and its associated policies. The fewer classes you create, the easier the process of deployment and ongoing maintenance should be.

The Imperative of Implementing QoS

Some might question whether QoS is needed in today’s environments of instant capacity expansion via cloud services. However, to properly protect applications from network congestion, organizations still must focus their efforts on identifying and addressing the most common causes of potentially crippling situations. Quality of service tools are often used to help overcome:

Low bandwidth: A problem when capacity is not enough to handle all traffic types sent at once.

Poor Network design: Your network topology must be designed not to ensure that all parts of your network are connected and to enhance performance across all coverage areas. Correct subnetting ensures that traffic flows towards the destined network and stays in that same network, which reduces congestion.

Outdated hardware: Bottlenecks can occur when data is transported through obsolete switches, routers, servers, and Internet exchanges. If the hardware isn’t up to par, a slowdown in data transmission occurs.

Too many devices in the broadcast domain: When you put too many hosts or multiple devices in a broadcast domain, you get a congested network.

Broadcast storms: Too many requests or broadcast traffic in a network.

High processor utilization: Network devices are designed to handle a certain maximum data speed. Constantly pushing larger data would result in overutilized devices.

Enhancing User Experience through Latency Reduction

Network latency refers to the time it takes for data to travel from its source to its destination. From a user standpoint, it often refers to how long a page or application takes to load.

The stakes are high. Businesses that rely on real-time interactions or high-speed data processing, even a slight delay, can be the difference between a satisfied customer and a lost sale.

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QoS Deployment Strategies

Before an organization can configure any QoS tools, like queuing, policing, or shaping, IT must look at the traffic that is coursing through our network device and identify it first. QoS classification refers to the process of classifying the type of IP packets or traffic. Traffic types can be data, video, or voice traffic. Traffic classes are the categories of traffic that are grouped based on their similarity. Other steps to take include:

QoS Traffic Marking

After the classification of IP packet headers based on their contents, QoS Marking includes setting bits inside a data link or network layer header, with the intention of letting other devices' QoS tools classify traffic based on those marked values, according to Study CCNA.

Managing Congestion with Smart Networking Tools

Powerful and potent networking tools can add much-needed smarts to efforts to manage congestion in your network.

Because of ongoing changes to the traffic mix and volume, implementing QoS is anything but a set it and forget it undertaking, bandwidth monitoring and traffic analysis are crucial components in optimizing network performance.

By closely monitoring bandwidth usage and analyzing traffic patterns, organizations can gain valuable insights into their network infrastructure, identify potential bottlenecks, and make informed decisions to maximize their available resources.

There are numerous network monitoring tools available in the market that provide real-time visibility into bandwidth usage and network traffic. “These tools collect data from various sources such as routers, switches, and firewalls, and present it in a user-friendly interface for analysis,” according to FasterCapital.

Navigating QoS Challenges

Like any other solution designed to help improve network performance, QoS delivers benefits that are only achievable if the obstacles incurred when using the technology can be overcome. Some common things that limit the benefits of a QoS implementation include:

Latency

QoS enables organizations to reduce latency, or speed up the process of a network request, by prioritizing their critical application. These capabilities solve problems with routers taking too long to analyze information and storage delays caused by intermediate switches and bridges.

Complexity and overhead

QoS adds complexity and overhead to network configuration and management. Therefore, you must define and apply parameters such as traffic classes, queues, policies, rules, and metrics. You also need to monitor and troubleshoot the QoS performance and adjust the settings as needed. This can be challenging and time-consuming.

Trade-offs and costs

QoS involves trade-offs and costs that might not be acceptable. With QoS, you might need to sacrifice network resources, such as bandwidth, memory, or processing power. You might also need to invest in additional hardware, software, or services, such as QoS-enabled devices, licenses, or contracts. Workarounds include using analysis, evaluation, or optimization to measure and improve the QoS value and efficiency.

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Balancing Over-Provisioning Concerns with QoS Needs

With the evolution of QoS and the longstanding practice of over provisioning, some have seen the situation as an either/or proposition.

Over provisioning is viable if cost is not an issue. Why not purchase twice the bandwidth, links, routers, etc. to ensure quality performance as ISPs do?

The best option for both worlds option is using quality of service and over-provisioning together as they are complementary. "QoS works within the constraints of the network bandwidth. If more bandwidth exists, the stress on QoS is decreased,” wrote John McCabe, in a Rutgers University paper. "If a major event (e.g., 9/11) occurs over-provisioning by itself will not solve the problem," he added.

Conclusion

Thirty years later, QoS technology still provides network engineers the means to prioritize latency-sensitive traffic flows as bandwidth consumption soars. It also generates a wealth of data that enables you to monitor, manage, and optimize your traffic when needed. This becomes particularly important in networking environments that meld on-premises, private, and public cloud elements.

For QoS to work best in such hybrid settings, network teams need to deploy, monitor, and adjust policies.

Combined with network monitoring tools that collect crucial metrics such as packet loss, jitter, delay, throughput, and utilization, QoS is still an IT team’s best friend. In a time of soaring traffic, they must also be able to provide clear and actionable reports and alerts and integrate with other network management systems.