What is IEEE802.1Qci?

TSN (Time Sensitive Network) employs IEEE802.1Qci (Per-Stream Filtering and Policing) to enable isolation from malicious attacks on the network and network device failures/abnormal conditions. This column provides an overview of IEEE802.1Qci.

802.1Qci is one of the IEEE 802.1 standards related to Ethernet networking. 802.1Qci, also known as per-stream FILTERS and policing at input ports, specifies procedures for FRAMES FILTERS and policing based on the specific data stream to FRAMES belongs.

Existing Ethernet standards implement bandwidth limiting functionality on input ports of SWITCHES devices, but they are unable to implement detailed bandwidth limiting for each input stream. They also do not implement FILTERS functionality for each stream. The 802.1Qci standard specifies bandwidth limiting and FILTERS functionality for each input stream, improving communication security and network robustness. 802.1Qci also implements bandwidth limiting using a policing method.

It is one of the bandwidth restriction methods. In addition to policing, shaping is another typical bandwidth restriction method. The difference between policing and shaping is as shown in Figure 1. With policing, traffic is discarded when the traffic rate exceeds the limit. On the other hand, with shaping, traffic is not discarded even if the traffic rate exceeds the limit, but is smoothed.

IEEE802.1Qci enables bandwidth control and filtering for each stream at the input port. The stream classification is specified by the user.
For Ethernet FRAMES input to an input port, each stream is defined, for example, Ethernet FRAMES with a destination MAC address of "xx.xx.xx.xx.xx.xx" are defined as stream 1, Ethernet FRAMES with an Ethernet Type of "xxxx" are defined as stream 2, etc.

802.1Qci implements per-stream FILTERS and policing at input ports using the configuration shown in Figure 2. An Ethernet FRAMES is received at the input port and checked to see which FRAMES it belongs to.
As shown in Figure 2, if an Ethernet FRAMES is determined to belong to stream 1, it is forwarded to the Stream Filter Block of Stream ID 1. There, it is checked whether it meets the filter conditions (for example, whether the Ethernet frame size is xx bytes or more), and if it does, the Ethernet FRAMES is discarded.
If the filter conditions are not matched, as shown in Figure 2, the Gate ID is set to "1", so the packet will be forwarded to the Gate with Gate ID 1.
Because the gate with Gate ID 1 is open, the Ethernet FRAMES passes through the gate. Then, because Stream ID 1 specifies Meter ID 1, the Ethernet FRAMES is forwarded to the meter with Meter ID 1. The meter performs bandwidth control by policing, and if the bandwidth limit is not exceeded, the frame is stored in the transmission queue.