Configuration Overview - Alcatel-Lucent OmniSwitch 6850-48 Network Configuration Manual

Configuring Spanning Tree Parameters
802.1q Tagged VLANs
For 802.1q tagged VLANs, Cisco uses a proprietary frame format which differs from the standard IEEE
BPDU format used by Alcatel-Lucent 1X1 mode, thus preventing Spanning Tree topologies for tagged
vlans from interoperating over the 802.1Q trunk.
In order to interoperate with Cisco PVST+ mode, the current Alcatel-Lucent 1x1 mode has an option to
recognize Cisco's proprietary PVST+ BPDUs and allow any user port on an OmniSwitch to send and
receive PVST+ BPDUs, so that loop-free topologies for the tagged VLANs can be created between
OmniSwitch and Cisco switches.

Configuration Overview

You can use the bridge mode 1x1 pvst+
on an OmniSwitch:
-> bridge mode 1x1 pvst+ enable
To disable the PVST+ mode interoperability mode on an OmniSwitch, use the following command:
-> bridge mode 1x1 pvst+ disable
The bridge port pvst+
connecting to a Cisco switch.
You can use the bridge port pvst+ command with the enable option to configure the port to handle only
the PVST+ BPDUs and IEEE BPDUs for VLAN 1 (Cisco native VLAN for CST). For example:
-> bridge port 1/3 pvst+ enable
The following will cause a port to exit from the enable state:
•
When the link status of the port changes.
•
When the administrative status of the port changes.
•
When the PVST+ status of the port is changed to disable or auto.
You can use the bridge port pvst+ command with the disable option to configure the port to handle only
IEEE BPDUs and to drop all PVST+ BPDUs. For example:
-> bridge port 1/3 pvst+ disable
You can use the bridge port pvst+ command with the auto option to configure the port to handle IEEE
BPDUs initially (i.e., disable state). Once a PVST+ BPDU is received, it will then handle PVST+ BPDUs
and IEEE BPDUs for a Cisco native VLAN. For example:
-> bridge port 1/3 pvst+ auto
Note. By default, a port is configured for PVST+ auto mode on an Omniswitch.
The following show command displays the PVST+ status.
-> show spantree mode
Spanning Tree Global Parameters
Current Running Mode
Current Protocol
OmniSwitch AOS Release 6 Network Configuration Guide
command to globally enable the PVST+ interoperability mode
command is used to configure how a particular port will handle BPDUs when
: 1x1,
: N/A (Per VLAN),
Spanning Tree Operating Modes
September 2009 page 13-15