Specifications

9-3
System Management Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches
Chapter 9 Configuring Port-Based Traffic Control
Information About Port-Based Traffic Control
The combination of the storm-control suppression level and the 1-second time interval controls the way
the storm control algorithm works. A higher threshold allows more packets to pass through. A threshold
value of 100 percent means that no limit is placed on the traffic. A value of 0.0 means that all broadcast,
multicast, or unicast traffic on that port is blocked.
Note Because packets do not arrive at uniform intervals, the 1-second time interval during which traffic
activity is measured can affect the behavior of storm control.
You use the storm-control interface configuration commands to set the threshold value for each traffic
type.
Protected Ports
Some applications require that no traffic be forwarded at Layer 2 between ports on the same switch so
that one neighbor does not see the traffic generated by another neighbor. In such an environment, the use
of protected ports ensures that there is no exchange of unicast, broadcast, or multicast traffic between
these ports on the switch.
Note NNIs default to non-protected ports. Since UNIs and ENIs s provide port isolation, protected port is not
available on UNI and ENI ports. For more information about port types, see the “UNI, NNI, and ENI
Port Types” section in Interfaces Software Configuration Guide for Cisco IE 2000U and Connected Grid
Switches.
Protected ports have these features:
• A protected port does not forward any traffic (unicast, multicast, or broadcast) to any other port that
is also a protected port. Data traffic cannot be forwarded between protected ports at Layer 2; only
control traffic, such as PIM packets, is forwarded because these packets are processed by the CPU
and forwarded in software. All data traffic passing between protected ports must be forwarded
through a Layer 3 device.
• Forwarding behavior between a protected port and a nonprotected port proceeds as usual.
Port Blocking
By default, the switch floods packets with unknown destination MAC addresses out of all ports. If
unknown unicast and multicast traffic is forwarded to a protected port, there could be security issues. To
prevent unknown unicast or multicast traffic from being forwarded from one port to another, you can
block a port (protected or nonprotected) from flooding unknown unicast or multicast packets to other
ports.
Port Security
This section includes the following topics:
• Secure MAC Addresses, page 9-4
• Security Violations, page 9-4