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Chapter 73 Error-Disable
XGS2220 Series User’s Guide
538
CHAPTER 73
Error-Disable
73.1 Error-Disable Overview
This chapter shows you how to configure the rate limit for control packets on a port, and set the Switch
to take an action (such as to shut down a port or stop sending packets) on a port when the Switch
detects a pre-configured error. It also shows you how to configure the Switch to automatically undo the
action after the error is gone.
73.1.1 CPU Protection Overview
Switches exchange protocol control packets in a network to get the latest networking information. If a
switch receives large numbers of control packets, such as ARP, BPDU or IGMP packets, which are to be
processed by the CPU, the CPU may become overloaded and be unable to handle regular tasks
properly.
The CPU protection feature allows you to limit the rate of ARP, BPDU and IGMP packets to be delivered
to the CPU on a port. This enhances the CPU efficiency and protects against potential DoS attacks or
errors from other networks. You then can choose to drop control packets that exceed the specified rate
limit or disable a port on which the packets are received.
73.1.2 Error-Disable Recovery Overview
Some features, such as loop guard or CPU protection, allow the Switch to shut down a port or discard
specific packets on a port when an error is detected on the port. For example, if the Switch detects that
packets sent out the ports loop back to the Switch, the Switch can shut down the ports automatically.
After that, you need to enable the ports or allow the packets on a port manually through the Web
Configurator or the commands. With error-disable recovery, you can set the disabled ports to become
active or start receiving the packets again after the time interval you specify.
73.1.3 What You Can Do
• Use the Errdisable Status screen (Section 73.2 on page 539) to view whether the Switch detected that
control packets exceeded the rate limit configured for a port or a port is disabled according to the
feature requirements and what action you configure, and related information.
• Use the CPU Protection screen (Section 73.3 on page 541) to limit the maximum number of control
packets (ARP, BPDU and/or IGMP) that the Switch can receive or transmit on a port.
• Use the Errdisable Detect screen (Section 73.4 on page 543) to have the Switch detect whether the
control packets exceed the rate limit configured for a port and configure the action to take once the
limit is exceeded.
• Use the Errdisable Recovery screen (Section 73.5 on page 544) to set the Switch to automatically
undo an action after the error is gone.
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