Edge-Core ECS3510-10PD, Management Manual

Page: 269 / 1494

C
HAPTER
9
| Congestion Control
Automatic Traffic Control
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The key elements of this diagram are described below:
◆
Alarm Fire Threshold – The highest acceptable traffic rate. When
ingress traffic exceeds the threshold, ATC sends a Storm Alarm Fire
Trap and logs it.
◆
When traffic exceeds the alarm fire threshold and the apply timer
expires, a traffic control response is applied, and a Traffic Control Apply
Trap is sent and logged.
◆
Alarm Clear Threshold – The lower threshold beneath which a control
response can be automatically terminated after the release timer
expires. When ingress traffic falls below this threshold, ATC sends a
Storm Alarm Clear Trap and logs it.
◆ When traffic falls below the alarm clear threshold after the release
timer expires, traffic control (for rate limiting) will be stopped and a
Traffic Control Release Trap sent and logged. Note that if the control
action has shut down a port, it can only be manually re-enabled using
Manual Control Release (see page 271 ).
◆ The traffic control response of rate limiting can be released
automatically or manually. The control response of shutting down a
port can only be released manually.
Figure 124: Storm Control by Shutting Down a Port
The key elements of this diagram are the same as that described in the
preceding diagram, except that automatic release of the control response
is not provided. When traffic control is applied, you must manually re-
enable the port.
Functional Limitations
Automatic storm control is a software level control function. Traffic storms
can also be controlled at the hardware level using Port Broadcast Control or
Port Multicast Control (as described on page 266 ). However, only one of
these control types can be applied to a port. Enabling automatic storm
control on a port will disable hardware-level storm control on that port.