Brocade Multi-Service IronWare QoS and Traffic Management Configuration Guide (Supporting R05.6.00) - Manual (Page 24)

10 Multi-Service IronWare QoS and Traffic Management Configuration Guide
53-1003037-02
Rate limiting BUM packets
1
Output such as the following is displayed.
policy-map pmap1
cir 106656 bps cbs 24000 bytes
eir 53328 bps ebs 20000 bytes
excess-priority 2 excess-dscp 43
policy-map pmap2
cir 106656 bps cbs 24000 bytes
eir 53328 bps ebs 30000 bytes
excess-priority 1 excess-dscp 30
This display shows the following information.
Rate limiting BUM packets
To prevent the CPU from being flooded by the broadcast, unknown-unicast, and multicast (BUM)
packets or bytes, you can restrict the number of BUM packets received on a port. If a high rate of
BUM traffic is received by the device on a given port, you can configure the per-port ingress rate
limit for the BUM traffic. When you configure a BUM rate limit, the device accepts the maximum
configured number of packets and drops additional BUM packets. A port can have BUM rate limits
independent of its interface module. The BUM packets entering the device are rate limited before
being replicated.
When the received BUM traffic exceeds the pre-defined rate limit, you can close or shut down the
physical port using the shutdown option of the rate-limit command. When the port is configured to
be shut down and the BUM traffic experiences packet drops due to the BUM rate limit, the port is
shut down automatically. The port shut down occurs within 2.5 seconds after the BUM traffic
exceeds the defined limit. The port can be enabled again using the no form of the rate-limit
command.
Limitations of the BUM rate limit
The configuration of the BUM rate limit has the following limitations:
• The BUM rate limit applies only to ingress ports.
• The per-port rate limit cannot be configured individually per traffic type of the broadcast,
unknown unicast, or multicast traffic.
• The port shutdown cannot be configured per traffic type.
• The BUM rate limit does not drop packets based on the priorities.
TABLE 4 Rate limit policy map parameters
This field... Displays...
policy-map The name of the policy map for which the configuration is being displayed
cir The value of the CIR configured for this policy map. Possible values are: 1 - 100000000000 bps.
cbs Value of the CBS configured for this policy map. Possible values are: 1250 - 12500000000 bytes.
eir Value of the EIR configured for this policy map. Possible values are: 1 - 100000000000 bps.
ebs Value of the EBS configured for this policy map. Possible values are: 1250 - 12500000000 bytes.