Figure 3: Bpdu Protection Topology - Juniper EX9200 Features Manual

Spanning-Tree Protocols Feature Guide for EX9200 Switches
Overview and Topology
220
Before you configure the interfaces on Switch 2 for BPDU protection, be sure you have:
RSTP enabled on the switches.
NOTE: By default, RSTP is enabled on all EX Series switches.
The switches, being in an RSTP topology, support a loop-free network through the
exchange of BPDUs. Receipt of outside BPDUs in an RSTP or MSTP topology, however,
can lead to network outages by triggering an STP misconfiguration. To prevent such
outages, enable BPDU protection on spanning tree interfaces that could receive outside
BPDUs. If an outside BPDU is received on a BPDU-protected interface, the interface shuts
down to prevent the outside BPDU from accessing the spanning tree interface.
Figure 3 on page 220 shows the topology for this example. In this example, Switch 1 and
Switch 2 are configured for RSTP and create a loop-free topology. The interfaces on
Switch 2 are edge access ports—edge access ports frequently receive outside BPDUs
generated by PC applications.
This example configures interface
Switch 2, and then configures BPDU protection on those ports. With BPDU protection
enabled, these interfaces shut down when they encounter an outside BPDU sent by the
PCs connected to Switch 2.

Figure 3: BPDU Protection Topology

ge-0/0/5 and interface ge-0/0/6
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as edge ports on