Chapter 5
Setup and Configuration
RUGGEDCOM RSG2488
User Guide
150
Configuring Classes of Service Globally
1.
Inspection Phase
In the inspection phase, the CoS priority of a received frame is determined from:
• A specific CoS based upon the source and destination MAC address (as set in the Static MAC Address
Table)
• The priority field in 802.1Q tags
• The Differentiated Services Code Point (DSCP) component of the Type Of Service (TOS) field, if the frame
is IP
• The default CoS for the port
Each frame’s CoS will be determined once the first examined parameter is found in the frame.
NOTE
For information on how to set the
Inspect TOS
parameter, refer to
Classes of Service for Specific Ethernet Ports”
.
The header of each received frame is first examined to determine if the frame is an IP packet and if
Inspect
TOS
is enabled in ROS. The CoS is determined from the DSCP field.
If the frame is not an IP packet or if
Inspect TOS
is disabled, the frame is examined to determine if its
destination or source MAC address is found in the Static MAC address table. If it is, the CoS configured for
the static Mac address is used. If neither destination or source MAC address is in the Static MAC Address
table, the frame is then examined for 802.1Q tags and the priority field is mapped to a CoS. If a tag is not
present, the default CoS for the port is used.
After inspection, the frame is forwarded to the egress port for transmission.
2.
Forwarding Phase
Once the CoS of the frame is determined, the frame is forwarded to the egress port, where it is collected into
one of the priority queues according to the assigned CoS.
CoS weighting selects the degree of preferential treatment that is attached to different priority queues. The
ratio of the number of higher CoS to lower CoS frames transmitted can be configured. If desired, the user can
configure lower CoS frames to be transmitted only after all higher CoS frames have been serviced.
The following sections describe how to configure and manage classes of service:
•
Section 5.3.1, “Configuring Classes of Service Globally”
•
Section 5.3.2, “Configuring Classes of Service for Specific Ethernet Ports”
•
Section 5.3.3, “Configuring Priority to CoS Mapping”
•
Section 5.3.4, “Configuring DSCP to CoS Mapping”
Section 5.3.1
Configuring Classes of Service Globally
To configure global settings for Classes of Service (CoS), do the following:
1. Navigate to
Classes of Service > Configure Global CoS Parameters
. The
Global CoS Parameters
form
appears.