External Switch Vlan Priority Settings - GE PACSystems RX3i User Manual

3.4 External Switch VLAN Priority Settings

If a system includes external switches, these switches must be configured to match the VLAN Priority
groupings listed below for the RX3i CEP.
The PROFINET-I/O specification indicates the VLAN priorities for each type of Ethernet traffic that originates
from a PROFINET IO-Device. VLAN priorities range from 0 to 7, with 7 being the highest.
The switch on an RX3i CEP Carrier supports just two traffic classes, giving two levels of preference. Incoming
traffic without a VLAN priority is assigned to the lowest priority traffic class. The following table lists the VLAN
priorities, and their corresponding priorities in the RX3i CEP:
VLAN Priority
7, 6, 5
4, 3, 2, 1, 0
An external switch that supports only two traffic queues must be configured like the RX3i CEP Carrier, as listed
in the table above. An external switch that does not support a VLAN priority mapping that exactly matches the
mapping used by the RX3i CEP Carrier can be used if it can be configured with the following relationships
between VLAN priorities:
• VLAN Priority 7 is forwarded with at least as much preference as VLAN Priority 6.
• VLAN Priority 6 is forwarded with at least as much preference as VLAN Priority 5.
• VLAN Priority 5 is forwarded with more preference than VLAN Priorities 0, 1, 2, 3 and 4.
If the external switch does not allow VLAN priority 4 to be treated differently from priority 5, it should be used
only if no device on the network will generate VLAN Priority 4 Ethernet Traffic.
GFK-2883E
Preference / Traffic Class
Real-time (High Priority).
This includes the following Ethernet traffic:
PTCP, MRP, MRRT, RT_CLASS_2, RT_CLASS_1, RT_CLASS_UDP, High
Priority RTA_CLASS_1, High Priority RTA_CLASS_UDP, Low Priority
RTA_CLASS_1, Low Priority RTA_CLASS_UDP.
Non-real-time (Lower Priority).
This includes the following Ethernet traffic:
IP, DCP, and other untagged traffic.
March 2018
Chapter 3. Installation and Mounting
33