Traffic Classification Methods
Traffic classification can be achieved through various methods such as:
1. Port based classification
Port-based classification is defined as a type of traffic classification method where port numbers from the transport layer are used to identify the application concerning traffic. This type of classification method is supported by many networking devices and consumes fewer resources. Port-based classification method has a limitation in that it can be used only for services and applications that have fixed port numbers. For example, HTTP (Hyper Text Transfer Protocol) makes use of port 80.
2. Deep Packet Inspection (DPI)
Deep Packet Inspection(DPI) is defined as a technique of traffic classification where all the contents of packets are inspected and analyzed in real-time. The deep packet inspection method analyses the packet data at the application layer. This method checks for actual payload along with the data that is transmitted. The deep packet inspection method provides more accurate results but has a drawback in that it is more resource-intensive. The packets in the DPI method are evaluated based on the rules that are stated by network administrators.
3. Signature-Based Classification
Signature-based classification method makes use of predefined patterns and signatures for identifying the protocols that are used over the internet. Whenever any incoming traffic passes through the classification system, the new patterns or data is compared with the patterns and signatures already stored in the database. This type of method is mainly used for well-known applications and services.
Differentiated Services (DiffServ) and Traffic Classification
Differentiated Services (DiffServ) is defined as a class of service(COS) model that is used to describe and control the IP network traffic by class. The main aim of differentiated services is to give priority to the specific traffic that needs an uninterrupted flow of data. In Differentiated services, the traffic is divided into multiple classes and each class is treated and prioritized differently. This technique of classification used by differentiated services is useful when there are limited or less number of resources. Differentiated services work at the Network layer of the Open Systems Interconnection(OSI) Model. An example of Differentiated services is voice traffic.
As compared to the quality of service (QoS) approach Differentiated services provide with more scalable and flexible way of controlling the traffic. In the Differentiated Services model, each packet is given one of the 64 possible forwarding behaviors also known as per-hop behavior (PHBs).PHB is used to define the packet forwarding procedure of each node that is determined by the DiffServ code point.