Rstp Or Vstp Forced To Run As Ieee 802.1D Stp; Convergence - Juniper EX9200 Features Manual

Spanning-Tree Protocols Feature Guide for EX9200 Switches

RSTP or VSTP Forced to Run as IEEE 802.1D STP

Related
Documentation
Configuring a Spanning-Tree Instance Interface as an Edge Port for Faster Convergence
8
On MX Series routers and EX Series and QFX Series switches in a Layer 2 environment,
you can force the configured Rapid Spanning Tree Protocol (RSTP) or VLAN Spanning
Tree Protocol (VSTP) to run as the original IEEE 802.1D Spanning Tree Protocol (STP)
version. Configure original IEEE_802.1D STP for compatibility with older bridges that do
not support RSTP or VSTP.
Keep the following limitations in mind when RSTP or VSTP are forced to run as the original
STP version:
If you configure an instance interface as an edge port, the configuration statement is
ignored.
If you configure point-to-point link mode for an instance interface, the configuration
statement is ignored.
Configuring RSTP (CLI Procedure) on page 33
Configuring VLAN Spanning Tree Protocol on page 168
Reverting to RSTP or VSTP from Forced IEEE 802.1D STP on page 34
force-version on page 40
RSTP, MSTP, and VSTP instance interfaces configured as edge ports enable the protocol
to converge faster than the original IEEE 802.1D STP version. Edge ports transition directly
to the forwarding state, and so the protocol does not need to wait for BPDUs to be
received on edge ports.
The Junos OS supports automatic detection of edge ports as described in the RSTP
standard. Layer 2 bridges do not expect to receive BPDUs for edge ports. If a BPDU is
received for an edge port, the port becomes a non-edge port.
Keep the following guidelines in mind when configuring spanning-tree instance interfaces
as edge ports:
Do not configure a spanning-tree instance interface as an edge port if it is connected
to any Layer 2 bridge. An instance interface connected to Layer 2 bridges but configured
as an edge port can cause physical loops.
if the spanning-tree protocol is configured to run the original IEEE 802.1D spanning-tree
version, the edge-port option (if configured) is ignored.
If edge ports are configured at both the VSTP global and VLAN levels, the configuration
at the VLAN level overrides the global configuration.
Copyright © 2017, Juniper Networks, Inc.