Users Guide

Fabric OS Administrator’s Guide 415

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QoS

Limiting traffic from a particular device

1. Connect to the switch and log in using an account with admin permissions.

2. Enter the portCfgQos

--setratelimit command.

portcfgqos --setratelimit [slot/]port ratelimit

Example of setting the rate limit on slot 3, port 9 to 4000 Mbps

portcfgqos --setratelimit 3/9 4000

Disabling Ingress Rate Limiting

1. Connect to the switch and log in using an account with admin permissions.

2. Enter the portCfgQos

--resetratelimit command.

portcfgqos --resetratelimit [slot/]port

Example of disabling Ingress Rate Limiting on slot 3, port 9

portcfgqos --resetratelimit 3/9

QoS

Quality of Service (QoS) allows you to categorize the traffic flow between a host and a target as

having a high, medium, or low priority.

Fabric OS supports two types of prioritization:

• Class-Specific Control (CS_CTL)-based frame prioritization

Each frame between a host and a target is assigned a specific priority, depending on the value

of the CS_CTL field in the frame header.

• QoS zone-based traffic prioritization

All traffic between a host and a target is assigned a specific priority, depending on the name

you define for the QoS zone.

CS_CTL-based frame prioritization and QoS zone-based traffic prioritization are mutually exclusive.

If you enable CS_CTL-based frame prioritization on F_Ports or FL_Ports, then QoS zone-based

traffic prioritization cannot be used between any devices connected to the F_Ports or FL_Ports.

CS_CTL-based frame prioritization takes precedence over QoS zone-based traffic prioritization. If

you enable CS_CTL-based frame prioritization on F_Ports or FL_Ports that are defined in a QoS

zone, CS_CTL-based frame prioritization takes precedence over the QoS zones.

Table 71 shows a basic comparison between CS-CTL-based frame prioritization and QoS

zone-based traffic prioritization. Refer to “CS_CTL-based frame prioritization” on page 416 and

“QoS zone-based traffic prioritization” on page 419 for detailed information about each type of

prioritization scheme.