Overview of SAC
Traditional traffic classification technologies only check the content at Layer 4 and lower layers in packets, for example, source IP address, destination IP address, source port number, destination port number, and service type. They cannot analyze applications in packets. Leveraging service awareness (SA) technology, Smart Application Control (SAC) detects and identifies Layer 4 to Layer 7 information in packets and dynamic protocols such as HTTP and RTP through a smart application protocol identification and classification engine. This allows it to implement fine-grained QoS management according to the identification result. In this way, SAC implements application-based traffic control.
SAC uses the signature identification technology, a basic SA technology, to identify and classify application traffic. Different applications use different protocols, each with its own characteristics, called signatures, which can be a specific port, a character string, or a bit sequence. The system analyzes traffic flowing through the device, and compares the analysis result with the signature database file loaded on the device. It identifies an application by detecting signatures in data packets, and implements fine-grained QoS management according to the identification result. Figure 1 shows the working mechanism of SAC.
Huawei analyzes the signatures of common applications and develops an application signature database file. After the application signature database file is loaded on a switch, the switch classifies traffic of all applications that can be identified. For example, P2P file sharing applications such as BT and eDonkey_eMule fall into the FileShare_P2P category. To check the applications that can be identified by the device and their categories, run the display application command.