ECS4660-28F_Management Guide-R03

C HAPTER 34 | Congestion Control Commands
Storm Control Commands
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COMMAND USAGE
◆ When traffic exceeds the threshold specified for broadcast and
multicast or unknown unicast traffic, packets exceeding the threshold
are dropped until the rate falls back down beneath the threshold.
◆ Traffic storms can be controlled at the hardware level using this
command or at the software level using the auto-traffic-control
command. However, only one of these control types can be applied to a
port. Enabling hardware-level storm control on a port will disable
automatic storm control on that port.
◆ The rate limits set by this command are also used by automatic storm
control when the control response is set to rate limiting by the auto-
traffic-control action command.
◆ Using both rate limiting and storm control on the same interface may
lead to unexpected results. It is therefore not advisable to use both of
these commands on the same interface.
EXAMPLE
The following shows how to configure broadcast storm control at 600
packets per second:
Console(config)#interface ethernet 1/5
Console(config-if)#switchport broadcast packet-rate 600
Console(config-if)#
switchport block This command prevents the flooding of broadcast, unknown multicast, or
unknown unicast packets onto an interface. Use the no form to restore the
default setting.
SYNTAX
[no] switchport block {broadcast | multicast | unicast}
broadcast - Specifies broadcast packets.
multicast - Specifies unknown multicast packets.
unicast - Specifies unknown unicast packets.
COMMAND MODE
Interface Configuration (Ethernet, Port Channel)
DEFAULT SETTING
Disabled
COMMAND USAGE
By default, broadcast, unknown multicast, and unknown unicast traffic is
flooded to all ports. This occurs if a MAC address has been timed out or not
yet learned by the switch. If this kind of traffic is flooded to an isolated port
on a private VLAN, there could be security issues.