Loop Guard; Chapter 26 Loop Guard; Loop Guard Overview; What You Can Do - ZyXEL Communications GS2210 Series User Manual

26.1 Loop Guard Overview

This chapter shows you how to configure the Switch to guard against loops on the edge of your
network.
Loop guard allows you to configure the Switch to shut down a port if it detects that packets sent out
on that port loop back to the Switch. 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 148 Loop Guard vs. STP

Loop Guard

Refer to Section 26.1.2 on page 212

26.1.1 What You Can Do

Use the Loop Guard screen
specific ports.

26.1.2 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 Switch 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:
GS2210 Series User's Guide
C
HAPTER
for more information.
(Section 26.2 on page 214) to enable loop guard on the Switch and in
2 6
Loop Guard
STP
212