Functions of Multiple Stream Reservation Protocol MSRP performs the following functions: • Allows Talkers to advertise Streams and Listeners to discover and register for Streams. • Establishes a path through an Ethernet between a Talker and one or more Listeners. • Provides guaranteed bandwidth for AVB Streams. • Guarantees an upper bound on latency. • Discovers and reports the worst case end-to-end latency between the Talker and each of its Listeners. • Reports failure reason and location when a path between the Talker and a Listener cannot satisfy bandwidth requirements. • Supports multiple classes of traffic with different latency targets.
• Protects best effort traffic from starvation by limiting AVB traffic. • MSRP Talker declarations are not forwarded along the STP blocked ports. • MSRP listens to the STP TCN notification to generate MSRP declarations tear /modify / establish streams. Information about Hierarchical QoS AVB networks guarantee bandwidth and minimum bounded latency for the time-sensitive audio and video streams. AVB defines Class A and Class B as the time-sensitive streams, based on the worst-case latency targets of the traffic from talker to listener. The latency targets for the two streams are listed as below: • SR-Class A: 2ms • SR-Class B:
50ms The sum of the worst-case latency contributions per hop should result in an overall end-to-end latency of 2 ms or less for SR-Class A and 50ms or less for SR-Class B. A typical AVB deployment of 7 hops from talker to listener meets these latency requirements. The priority code points map the traffic to the specific stream. Frame forwarding behavior is based on this priority. A credit-based shaper is used to shape the transmission of these streams in accordance with the bandwidth that has been reserved on a given outbound queue so that the latency targets are met. AVB supports hierarchical QoS. AVB Hierarchical QoS policy is two level Parent-Child Policy.
AVB Parent policy segregates audio, video traffic streams(SR-Class A , SR-Class B) and Network Control packets from standard best-effort Ethernet traffic (Non-SR) and manage streams accordingly. Hierarchical QoS allows you to specify QoS behavior at multiple policy levels, which provides a high degree of granularity in traffic management. You can use hierarchical policies to: • Allow a parent class to shape multiple queues in a child policy. • Apply specific policy map actions on the aggregate traffic. • Apply class-specific policy map actions. Configuring Audio Video Bridging Functions of Multiple Stream Reservation Protocol Configuring Audio Video Bridging 5