DSCP-based QoS configuration

Ruckus FastIron releases support basic DSCP-based QoS (also called Type of Service [ToS]-based QoS). However, the FastIron family of switches does not support other advanced DSCP-based QoS features.

Ruckus FastIron releases also support marking of the DSCP value. The software can read Layer 3 Quality of Service (QoS) information in an IP packet and select a forwarding queue for the packet based on the information. The software interprets the value in the six most significant bits of the IP packet header 8-bit ToS field as a DSCP value, and maps that value to an internal forwarding priority.

Note: MAC filter and DSCP marking cannot be configured on the same port.

The internal forwarding priorities are mapped to one of the eight forwarding queues (qosp0 through qosp7) on the Ruckus device. During a forwarding cycle, the device gives more preference to the higher-numbered queues, so that more packets are forwarded from these queues. For example, queue qosp7 receives the highest preference, while queue qosp0, the best-effort queue, receives the lowest preference.

Application notes for DSCP-based QoS

  • DSCP-based QoS is not automatically honored for routed and switched traffic. The default is 802.1p to CoS mapping. To honor DSCP-based QoS, you must either use an ACL or enable trust DSCP. .
  • When DSCP marking is enabled, the device changes the contents of the inbound packet ToS field to match the DSCP-based QoS value.

Using ACLs to honor DSCP-based QoS

This section shows how to configure Ruckus devices to honor DSCP-based QoS for routed and switched traffic.

DSCP-based QoS is not automatically honored for switched traffic. The default is 802.1p to CoS mapping. To honor DSCP-based QoS, you must enter the trust dscp command at the interface level of the CLI.

When the trust dscp command is enabled, the interface honors the Layer 3 DSCP value. By default, the interface honors the Layer 2 CoS value.

Note: On Ruckus ICX 7650 devices, configuring the trust dscp command to honor DSCP-based QoS classification on the ingress port works on all traffic except GRE tunnels; classification on these remains based on Layer 2 (802.1p) trust. For GRE tunnels, you can use ACLs to configure classification based on the DSCP value.

Remarking configuration considerations and limitations

  • When an ACL is configured on a port without remarking and global DSCP remarking is enabled, the global DSCP remarking is enabled for the permitted traffic.
  • DSCP and CoS global remarking are supported on the same interface together.
  • DSCP and CoS global remarking cannot coexist with MAC filters and MAC-based VLANs.

The following table summarizes the behavior when the remarking is set.

Table 1. DSCP remarking

DSCP

Remarking set

Not set

DSCP action

Remark DSCP at the ingress

N/A

Traffic class

Apply the TC equivalent to DSCP

Apply the TC equivalent to PCP

Table 2. PCP remarking

CoS

Remarking set

Remarking set

PCP action

Remark PCP at the egress

Remark PCP at the egress

Traffic class

N/A

Apply the TC equivalent to PCP