8 Per-Stream Filtering and Policing (PSFP)

Per-stream Filtering and Policing (PSFP), as defined in the IEEE 802.1Qci standard, provides filtering and policing, and service class selection for a stream.

A stream is defined in the same way as in FRER but the stream IDs may be different. The following figure shows the architecture of the PSFP.

Figure 8-1. Architecture of the PSFP
A diagram of a flowchart Description automatically generated

The stream filter instance table is an ordered list of stream filters where smaller identifier values appear earlier in the ordered list. This is especially important to know if wild-card match parameters are used. If a frame matches more than one stream filter, the stream filter that is selected is the one that is located earliest in the list.

Each stream filter instance has a reference to a stream gate instance, and, optionally, a reference to a flow meter instance.

The port parameter in the stream filter instance definition is not a part of the current standard but is added in order to support different filters for each of the replicated streams in FRER.

While configuring the stream filters for PSFP, the hardware imposes the following restrictions on the configuration:

  • The maximum number of stream filter instances using the same stream ID is two.
  • Both of these instances must be configured with the same priority (specific or wildcard).
  • Both of these instances must be configured with different ports, and both ports must be specific (non wildcard).

The easiest way to avoid error messages due to these restrictions is to first configure priority and port and then the stream ID.