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28.1 Loop Guard Overview
This chapter shows you how to configure the OLT to guard against loops on the edge of your network.
Loop guard allows you to configure the OLT to shut down a port if it detects that packets sent out on
that port loop back to the OLT. While you can use Spanning Tree Protocol (STP) to prevent loops in the
core of your network. STP cannot prevent loops that occur on the edge of your network.
Figure 147 Loop Guard vs. STP
Refer to
Section 28.1.2 on page 246
28.1.1 What You Can Do
Use the Loop Guard screen
ports.
28.1.2 What You Need to Know
Loop guard is designed to handle loop problems on the edge of your network. This can occur when a
port is connected to a OLT that is in a loop state. Loop state occurs as a result of human error. It happens
when two ports on a switch are connected with the same cable. When a switch in loop state sends out
broadcast messages the messages loop back to the switch and are re-broadcast again and again
causing a broadcast storm.
If a switch (not in loop state) connects to a switch in loop state, then it will be affected by the switch in
loop state in the following way:
• It will receive broadcast messages sent out from the switch in loop state.
• It will receive its own broadcast messages that it sends out as they loop back. It will then re-broadcast
those messages again.
for more information.
(Section 28.2 on page
247) to enable loop guard on the OLT and in specific
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H A P T E R
Loop Guard
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