Understanding Vstp For Ex Series Switches - Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual

Complete Software Guide for Junos

Understanding VSTP for EX Series Switches

Related
Documentation
1760
®
OS for EX Series Ethernet Switches, Release 10.4
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 factory
configuration for EX Series switches uses RSTP. If you use VLANs, however, we
recommend that you enable MSTP unless your network requires the device compatibility
provided by VSTP. Switches configured to run VSTP automatically assign each VLAN to
one spanning-tree instance that runs RSTP. While this approach is useful to optimize
network usage in small networks with a limited number of VLANs, a VSTP configuration
in networks with several hundred VLANs can overload switch CPUs. MSTP ensures that
your network doesn't slow down from the increased network traffic caused by hundreds
of VLANs, each with its own spanning-tree instance.
When using VSTP, you can selectively configure up to 253 VLANs; additional VLANs are
automatically configured to use RSTP. (VSTP and RSTP are the only spanning-tree
protocols that can be configured concurrently on a switch.) If your network includes
802.1D 1998 bridges, you can explicitly configure STP on those devices. When you explicitly
configure STP, the EX Series switch uses the IEEE 802.1D 2004 specification, force version
0, which is an RSTP configuration that is compatible with basic STP. For more information,
see "Configuring STP (CLI Procedure)" on page 1814.
NOTE: When you configure VSTP, we recommend that you enable VSTP on
all VLANs that can receive VSTP Bridge Protocol Data Units (BPDUs).
Understanding STP for EX Series Switches on page 1751
Understanding RSTP for EX Series Switches on page 1753
Understanding MSTP for EX Series Switches on page 1755
Understanding Layer 2 Protocol Tunneling on EX Series Switches on page 1520
Configuring VLAN Spanning Tree Protocol (CLI Procedure) on page 1818
Copyright © 2010, Juniper Networks, Inc.