Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) - Manual (Page 376)

• You can use Top Talkers to identify the SID/DID pairs that consume the most bandwidth and can
then configure them with certain QoS attributes so they get proper priority.
• If the bottleneck detection feature detects a latency bottleneck, you can use TI zones or QoS to
isolate latency device traffic from high-priority application traffic.
• If the bottleneck detection feature detects ISL congestion, you can use Ingress Rate Limiting to slow
down low-priority application traffic if it is contributing to the congestion.
Ingress Rate Limiting
Ingress Rate Limiting restricts the speed of traffic from a particular device to the switch port.
Use Ingress Rate Limiting for the following situations:
• To reduce existing congestion in the network or proactively avoid congestion.
• To enable you to offer flexible bandwidth-limit services based on requirements.
• To enable more important devices to use the network bandwidth during specific services, such as
network backup.
To limit the traffic, you set the maximum speed at which the traffic can flow through a particular F_Port
or FL_Port. For example, if you set the rate limit at 4 Gbps, then traffic from a particular device is
limited to a maximum of 4 Gbps.
Ingress Rate Limiting enforcement is needed only if the port can run at a speed higher than the rate
limit. For example, if the rate limit is 4 Gbps and the port is only a 2-Gbps port, then Ingress Rate
Limiting is not enforced.
The Ingress Rate Limiting configuration is persistent across reboots.
You should keep in mind the following considerations about Ingress Rate Limiting:
• Ingress Rate Limiting is applicable only to F_Ports and FL_Ports.
• QoS takes precedence over Ingress Rate Limiting.
• Ingress Rate Limiting is not enforced on trunked ports.
• Ingress Rate Limiting can also be used on simulation ports (SIM ports).
Virtual Fabrics considerations
If Virtual Fabrics is enabled and if a port is configured to have a certain rate limit value, you must first
disable the rate limit on the port before moving it to a different logical switch. Ports cannot be moved
when they have rate limit configured on them.
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
Ingress Rate Limiting
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