Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual page 1903

Example: Configuring BPDU Protection on non-STP Interfaces to Prevent STP
Miscalculations on EX Series Switches
Requirements
Overview and Topology
Copyright © 2010, Juniper Networks, Inc.
Understanding BPDU Protection for STP, RSTP, and MSTP on EX Series Switches on
page 1756
EX Series switches provide Layer 2 loop prevention through Spanning Tree Protocol
(STP), Rapid Spanning Tree protocol (RSTP), and Multiple Spanning Tree Protocol
(MSTP). Configure BPDU protection on non-STP interfaces that are connected to switches
with spanning trees to prevent the non-STP interfaces from receiving BPDUs. When
non-STP interfaces receive BPDUs, it can result in an STP misconfiguration, which could
lead to network outages.
This example describes how to configure BPDU protection on non-STP interfaces on an
EX Series switch:
Requirements on page 1799
Overview and Topology on page 1799
Configuration on page 1801
Verification on page 1801
This example uses the following hardware and software components:
Junos OS Release 9.1 or later for EX Series switches
One EX Series switch in an RSTP topology
One EX Series switch that is not in a spanning-tree topology
Before you configure the interface for BPDU protection, be sure you have:
RSTP operating on Switch 1.
Disabled RSTP on Switch 2.
NOTE: By default, RSTP is enabled on all EX Series switches.
A loop-free network is supported through the exchange of a special type of frame called
bridge protocol data unit (BPDU). Receipt of BPDUs on certain interfaces can lead to
network outages by triggering an STP miscalculation. Enable BPDU protection on those
interfaces that should not receive BPDUs to prevent network outages.
BPDU protection for non-STP interfaces can be enabled on interfaces on a non-STP
switch connected to an STP switch through a trunk interface. Enable BPDU protection
on interfaces on which no BPDUs are expected, such as access ports connected to user
Chapter 71: Examples of Spanning-Tree Protocols Configuration
1799