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Chapter 16

Traffic Control and Classification

RUGGEDCOM ROX II

CLI User Guide

714 Configuring Classes of Service

▫ 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.

Received frames are first examined to determine if their destination or source MAC address is found in the Static

MAC Address Table. If they are, 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 frame is examined to determine if it is an IP frame. If

the frame is IP and inspecting TOS is enabled, the CoS is determined from the DSCP field. If the frame is not IP or

inspecting TOS is disabled, the default CoS for the port is used.

After inspection, the frame is forwarded to the egress port for transmission.

• 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.

CONTENTS

• Section16.3.1, “Configuring Classes of Service”

• Section16.3.2, “Managing Priority-to-CoS Mapping”

• Section16.3.3, “Managing DSCP-to-CoS Mapping”

Section16.3.1

Configuring Classes of Service

To configure Classes of Service, do the following:

1. Make sure the CLI is in Configuration mode.

2. Configure the CoS weighting by typing:

switch classes-of-service cos-weighting weighting

Where:

• weighting is the weighting algorithm for transmitting different priority CoS frames. During traffic bursts,

frames queued in the switch pending transmission on a port may have different CoS priorities.

3. If necessary, configure CoS mapping based on either the IEEE 802.1p priority or Differentiated Services (DS)

field set in the IP header for each packet. For more information, refer to Section16.3.2.2, “Adding a Priority-

to-CoS Mapping Entry” or Section16.3.3.2, “Adding a DSCP-to-CoS Mapping Entry”.

4. Type commit and press Enter to save the changes, or type revert and press Enter to abort.

Siemens RUGGEDCOM ROX II User Manual

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