The maximum number of hops is 7. The per-port peer delay provided by gPTP and the network bridge residence delay are added to calculate the accumulated delays and ensure the latency requirement is met. Control traffic has the third highest priority and includes gPTP and SRP traffic. IEEE 802.1Qav time-aware scheduler introduces Class CDT for realtime control data from sensors and command streams to actuators, with worst-case latency of 100 μs over 5 hops, and maximum transmission period of 0.5 ms. Class CDT takes the highest priority over classes A, B, and control traffic. The measurement interval is 125 μs for Class A traffic and 250 μs for Class B. The SRP works using the Multiple MAC Registration Protocol (MMRP), the Multiple VLAN Registration Protocol (MVRP), and the Multiple Stream Registration Protocol (MSRP). MMRP controls propagation of group registration, and MVRP controls VLAN membership (MAC address information). MSRP works in a distributed network of bridges and end stations; it registers and advertises data streams and reserves bridge resources to provide the QoS guarantees. The SRP protocol essentially operates in the following sequence: A station (talker) sends a reservation request with the general MRP application. All participants in the stream have an MSRP application and the MRP Attribute Declaration (MAD) specification for describing the stream characteristics. Then each bridge within the same SRP domain can map, allocate, and forward the stream with the necessary resources by using the MRP attribute propagation.