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Monitoring CoS Forwarding Classes

Purpose

Use the monitoring functionality to view the current assignment of CoS forwarding classes to queue numbers on the system.

Action

To monitor CoS forwarding classes in the CLI, enter the following CLI command:

user@switch> show class-of-service forwarding-class

Meaning

Some switches use different forwarding classes, output queues, and classifiers for unicast and multidestination (multicast, broadcast, destination lookup fail) traffic. These switches support 12 forwarding classes and output queues, eight for unicast traffic and four for multidestination traffic.

Some switches use the same forwarding classes, output queues, and classifiers for unicast and multidestination traffic. These switches support eight forwarding classes and eight output queues.

Table 1 summarizes key output fields on switches that use different forwarding classes and output queues for unicast and multidestination traffic.

Table 1: Summary of Key CoS Forwarding Class Output Fields on Switches that Separate Unicast and Multidestination Traffic

Field

Values

Forwarding Class

Names of forwarding classes assigned to queue numbers. By default, the following unicast forwarding classes are assigned to queues 0, 3, 4, and 7, respectively:

  • best-effort—Provides no special CoS handling of packets. Loss priority is typically not carried in a CoS value.

  • fcoe—Provides guaranteed delivery for Fibre Channel over Ethernet (FCoE) traffic.

  • no-loss—Provides guaranteed delivery for TCP lossless traffic

  • network-control—Packets can be delayed but not dropped.

By default, the following multidestination forwarding class is assigned to queue 8:

  • mcast—Provides no special CoS handling of packets.

Queue

Queue number corresponding to (mapped to) the forwarding class name.

By default, four queues (0, 3, 4, and 7) are assigned to unicast forwarding classes and one queue (8) is assigned to a multidestination forwarding class:

  • Queue 0—best-effort

  • Queue 3—fcoe

  • Queue 4—no-loss

  • Queue 7—network-control

  • Queue 8—mcast

No-Loss

Packet drop attribute associated with each forwarding class:

  • Disabled—The forwarding class is configured for lossy transport (packets might drop during periods of congestion)

  • Enabled—The forwarding class is configured for lossless transport

    Note:

    To achieve lossless transport, you must ensure that priority-based flow control (PFC) and DCBX are properly configured on the lossless priority (IEEE 802.1p code point), and that sufficient port bandwidth is reserved for the lossless traffic flows.

    OCX Series switches do not support lossless transport.
Note:

OCX Series switches do not support the default lossless forwarding classes fcoe and no-loss, and do not support the no-loss packet drop attribute used to configure lossless forwarding classes. On OCX Series switches, do not map traffic to the default fcoe and no-loss forwarding classes (both of these default forwarding classes carry the no-loss packet drop attribute), and do not configure the no-loss packet drop attribute on forwarding classes.

Table 2 summarizes key output fields on switches that use the same forwarding classes and output queues for unicast and multidestination traffic.

Table 2: Summary of Key CoS Forwarding Class Output Fields on Switches That Do Not Separate Unicast and Multidestination Traffic

Field

Values

Forwarding Class

Names of forwarding classes assigned to queue numbers. By default, the following forwarding classes are assigned to queues 0, 3, 4, and 7, respectively:

  • best-effort—Provides no special CoS handling of packets. Loss priority is typically not carried in a CoS value.

  • fcoe—Provides guaranteed delivery for Fibre Channel over Ethernet (FCoE) traffic.

  • no-loss—Provides guaranteed delivery for TCP lossless traffic

  • network-control—Packets can be delayed but not dropped.

Queue

Queue number corresponding to (mapped to) the forwarding class name.

By default, four queues (0, 3, 4, and 7) are assigned to forwarding classes:

  • Queue 0—best-effort

  • Queue 3—fcoe

  • Queue 4—no-loss

  • Queue 7—network-control

No-Loss

Packet drop attribute associated with each forwarding class:

  • Disabled—The forwarding class is configured for lossy transport (packets might drop during periods of congestion).

  • Enabled—The forwarding class is configured for lossless transport.

    Note:

    To achieve lossless transport, you must ensure that priority-based flow control (PFC) and DCBX are properly configured on the lossless priority (IEEE 802.1p code point), and that sufficient port bandwidth is reserved for the lossless traffic flows.

    OCX Series switches do not support lossless transport.