In the world of networking, ensuring a smooth flow of traffic across the entire network is crucial. This is where traffic marking comes into play. By classifying traffic types into categories and adding Quality of Service (QoS) information to packet headers, network devices can make intelligent decisions on how to handle the traffic. Let’s explore the importance of traffic marking and its impact on network performance.
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The Power of Packet Marking
Imagine you have a phone call to make from a branch office. As the packets travel across the Wide Area Network (WAN) link to the head office, the phone adds extra information to the IP header. This information marks the packets as voice data, signaling their importance. When the packets reach the router at the head office, it quickly identifies the marking and prioritizes the voice traffic, ensuring it gets through even during times of congestion. By marking packets close to their source, we help other devices along the path make smart decisions when forwarding the packets.
Marking Flexibility
Packet markings are not set in stone. They can be changed or remarked at various points along the network. For instance, if you have public phones in the lobby of a building, the packets they generate will also be marked. However, you may consider these packets to be less important and assign them a lower priority by remarking them at a switch or router based on their source IP address. Additionally, you can choose to remark or strip the markings of traffic coming from untrusted sources like the internet.
Protecting Your Traffic
But what if your WAN provider decides to change your QoS markings? The only way to prevent this is by encrypting your traffic. Encryption ensures that your packet markings remain intact and cannot be modified by external entities. If you have concerns about the control your provider has over your QoS markings, it is essential to have a discussion and consider encryption as a protective measure.
Different Methods of Marking Traffic
There are various methods for marking traffic, each with its own benefits. Class of Service (CoS) uses layer two traffic and allows for eight different combinations of priority levels. IP precedence, an older method for layer three, allocates packets to eight categories based on their importance. The most common method is the Differentiated Services Code Point (DSCP) marking, which is compatible with both IPv4 and IPv6. DSCP marking assigns packets to forwarding classes and drop probabilities, allowing for more granular control over traffic prioritization.
Understanding Class and Drop Probability
Forwarding classes categorize traffic and enable network devices to make decisions based on their assigned class. There are eight forwarding classes, each with its own name, such as Assured Forwarding, Expedited Forwarding, and Best Effort. Within each forwarding class, there are three additional bits for drop probability, which act as subclasses. This allows for further differentiation within a class and ensures that packets with different priorities within the same class receive appropriate handling.
Simplified Traffic Marking
With so many different combinations of classes and drop probabilities, it can be overwhelming to decide which traffic goes where. However, you don’t have to use every combination. For smaller and simpler networks, starting with a four or five class model works well. This model includes classes for real-time traffic (voice and interactive video), critical data (business applications), best effort (default traffic), and scavenger (less important traffic). You can adjust the markings based on your specific needs, but keeping it simple makes future expansion easier.
Conclusion
Traffic marking plays a vital role in ensuring smooth network performance and prioritizing important traffic. By classifying traffic types and assigning appropriate markings, network devices can make intelligent decisions on how to handle packets throughout the network. Whether it’s voice data, critical business applications, or default traffic, the right markings and priorities help maintain a high-quality network experience. For more information on technology and networking, visit Techal.
FAQs
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Can my WAN provider change my QoS markings? While it is technically possible for your WAN provider to modify your QoS markings, encrypting your traffic can prevent such alterations. It’s essential to discuss this concern with your provider and consider encryption as a protective measure.
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What are the different methods for marking traffic? The three main methods for marking traffic are Class of Service (CoS), IP precedence, and Differentiated Services Code Point (DSCP). CoS focuses on layer two traffic, IP precedence on layer three, and DSCP is the most common method compatible with both IPv4 and IPv6.
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How can I simplify traffic marking? Starting with a four or five class model, such as the one described in this article, is a great way to simplify traffic marking for smaller and simpler networks. You can adjust the markings based on your specific needs, but keeping it simple makes future expansion easier.
