Brocade Multi-Service IronWare QoS and Traffic Management Configuration Guide (Supporting R05.6.00) - Manual (Page 25)

Multi-Service IronWare QoS and Traffic Management Configuration Guide 11
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Rate limiting BUM packets
1
• When the port reaches the configured rate limit, the device will check if the shutdown option is
enabled for the port.
• The device counts the rate of BUM packets received on the port, for every port configured for
shutdown.
• A single drop counter moves over each port to check for the shutdown option in a round robin
fashion.
• If the drop counter finds the BUM packets dropped on a port, the port will be shut down until
the port is explicitly enabled.
• Global BUM rate limiting is not supported on non-default ESI configured interfaces.
• The rate-limit is configured to count for a minimum of 10 milliseconds (ms) for a 1 GbE port
and 1 ms for a 10 GbE port.
• The granularity of the rate limit is 51200 bits for 1 Gigabit per second (Gbps) port and 512000
bits for 10 GbE port.
• Due to hardware limitations, 10G ports with BUM rate-limit can shutdown with a rate lower
than the actual configured shutdown threshold rate. When the minimum rate of 512Kbit/sec is
configured, 10K bit/sec will be rate limited. With a large shutdown threshold rate 2G bit/sec is
configured, 1.5G bit/sec will be rate limited. This limitation does not affect 1G ports.
Configuring per-port rate limiting for BUM traffic
For example, to configure the rate limit on BUM traffic packets to a million bits per second, on port
1/1, enter the following command.
Brocade(config-if-e1000-1/1)# rate-limit input broadcast unknown-unicast
multicast 1000000 shutdown
Syntax: [no] rate-limit input [broadcast | unknown-unicast | multicast] [average-rate [shutdown]]
The input parameter applies the rate limiting policy to traffic on inbound ports.
The broadcast, unknown-unicast, and multicast parameters define a rate limit for ingress
broadcast, unknown-unicast, and multicast packets on the port. Any combination of these
parameters can be used to define the rate limit.
The average-rate variable specifies the maximum number of bits a port is allowed to receive during
a one-second interval and is the aggregate sum of the broadcast, unknown-unicast, and multicast
packets rate limit, if the rate limit is configured for all three packets. The software automatically
adjusts the number you enter to the nearest multiple of 8,144 bits per second (bps).
The shutdown option specifies that the port is to be shut down if the amount of BUM traffic
exceeds the pre-defined limit.
When the user tries to add or modify an existing BUM rate limiting policy, the following error
message is displayed.
Error: There is already a rate limit policy applied on the port.
When the BUM traffic exceeds the defined rate limit, port 1/1 is shut down and the reason for the
shutdown is displayed in the output of the show interface command.
Brocade# show interface ethernet 1/1
GigabitEthernet1/1 is down (rate-limit BUM), line protocol is down
STP Root Guard is disabled, STP BPDU Guard is disabled