The ECN needs to be able to provide QoS (Quality of Service) and forward traffic according to priorities based on requirements.
The Consist Switch (CS) provides QoS and can assign priorities to messages according to ports, protocols, addresses, etc.
If necessary, the End Device (ED) can specify the priority in the sent messages.
Priority Levels
The QoS priority is divided into 8 levels, where 7 is the highest level and 0 is the lowest level. The default priority is 0.
QoS Support
If the CS supports QoS, there should be at least 2 priority queues. The CS assigns priorities to data according to application requirements.
If the ED needs to specify the priority of the sent message, it should use the DSCP of the IP segment. If the message has a VLAN tag, the ED may also use the PCP field in the MAC frame header. The binary representation of the DSCP field: LLL000 (LLL represents the priority from 0 to 7).
Ingress Rate Limiting
Ingress rate limiting is an optional feature for the CS. The CS may limit the rate of messages from the ED or the TBN. If the rate reaches the threshold, messages with lower priorities will be discarded first.
Egress Rate Limiting
Egress rate limiting is an optional feature for the CS. The CS may limit the rate of messages sent to the ED or the TBN. If the rate reaches the threshold, messages with lower priorities will be discarded first.
