Understanding Stp For Ex Series Switches - Juniper JUNOS OS 10.3 - SOFTWARE Manual

CHAPTER 64
Spanning-Tree Protocols—Overview

Understanding STP for EX Series Switches

Copyright © 2010, Juniper Networks, Inc.
Understanding STP for EX Series Switches on page 1519
Understanding RSTP for EX Series Switches on page 1520
Understanding MSTP for EX Series Switches on page 1521
Understanding BPDU Protection for STP, RSTP, and MSTP on EX Series
Switches on page 1522
Understanding Loop Protection for STP, RSTP, VSTP, and MSTP on EX Series
Switches on page 1523
Understanding Root Protection for STP, RSTP, VSTP, and MSTP on EX Series
Switches on page 1524
Understanding VSTP for EX Series Switches on page 1525
Juniper Networks EX Series Ethernet Switches provide Layer 2 loop prevention through
Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP), Multiple Spanning
Tree Protocol (MSTP), and VLAN Spanning Tree Protocol (VSTP). The default
spanning-tree protocol for EX Series switches is RSTP. RSTP provides faster convergence
times than STP. However, some legacy networks require the slower convergence times
of basic STP.
If your network includes 802.1D 1998 bridges, you can remove RSTP and explicitly
configure STP. See "Configuring STP (CLI Procedure)" on page 1580. When you explicitly
configure STP, the EX Series switches use the IEEE 802.1D 2004 specification, force
version 0. This configuration runs a version of RSTP that is compatible with the classic,
basic STP. If you use VLANs, you should enable VSTP and use it on your network. See
"Understanding VSTP for EX Series Switches" on page 1525.
You can use the same operational commands (show spanning-tree bridge and show
spanning-tree interface) to check the status of your spanning-tree configuration,
regardless of which spanning-tree protocol has been configured.
STP uses bridge protocol data unit (BPDU) packets to exchange information with other
switches. BPDUs send hello packets out at regular intervals to exchange information
across bridges and detect loops in a network topology. There are two types of BPDUs:
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