Figure 5: Network Topology For Loop Protection - Juniper EX9200 Features Manual

Table 25: Components of the Topology for Configuring Loop Protection on EX Series Switches
Property
Switch 1
Copyright © 2017, Juniper Networks, Inc.
A blocking interface can transition to the forwarding state in error if the interface stops
receiving BPDUs from its designated port on the segment. Such a transition error can
occur when there is a hardware error on the switch or software configuration error between
the switch and its neighbor. When this happens, a loop opens up in the spanning tree.
Loops in a Layer 2 topology cause broadcast, unicast, and multicast frames to
continuously circle the looped network. As a switch processes a flood of frames in a
looped network, its resources become depleted and the ultimate result is a network
outage.
CAUTION: An interface can be configured for either loop protection or root
protection, but not for both.
Three EX Series switches are displayed in
configured for RSTP and create a loop-free topology. Interface
traffic between Switch 3 and Switch 1; thus, traffic is forwarded through interface
on Switch 2. BPDUs are being sent from the root bridge on Switch 1 to both of these
interfaces.
This example shows how to configure loop protection on interface
it from transitioning from a blocking state to a forwarding state and creating a loop in
the spanning-tree topology.

Figure 5: Network Topology for Loop Protection

Table 25 on page 235 shows the components that will be configured for loop protection.
Settings
Switch 1 is the root bridge.
Chapter 10: Using BPDU Protection, Root Protection, and Loop Protection
Figure 5 on page 235. In this example, they are
is blocking
ge-0/0/6
ge-0/0/7
to prevent
ge-0/0/6
235