Configuration Guide User guide

FastIron Configuration Guide 1161
53-1002494-02
PVST/PVST+ compatibility
Commands on the Brocade Device
Brocade(config)#vlan-group 1 vlan 2 to 4
Brocade(config-vlan-group-1)#tagged ethernet 1/1
Brocade(config-vlan-group-1)#exit
Brocade(config)#interface ethernet 1/1
Brocade(config-if-1/1)#dual-mode
Brocade(config-if-1/1)#pvst-mode
These commands configure a VLAN group containing VLANs 2, 3, and 4, add port 1/1 as a tagged
port to the VLANs, and enable the dual-mode feature and PVST+ support on the port. The
dual-mode feature allows the port to send and receive untagged frames for the default VLAN (VLAN
1 in this case) in addition to tagged frames for VLANs 2, 3, and 4. Enabling the PVST+ support
ensures that the port is ready to send and receive PVST+ BPDUs. If you do not manually enable
PVST+ support, the support is not enabled until the port receives a PVST+ BPDU.
The configuration leaves the default VLAN and the port Port Native VLAN unchanged. The default
VLAN is 1 and the port Port Native VLAN also is 1. The dual-mode feature supports untagged
frames on the default VLAN only. Thus, port 1/1 can send and receive untagged BPDUs for VLAN 1
and can send and receive tagged BPDUs for the other VLANs.
Port 1/1 will process BPDUs as follows:
• Process IEEE 802.1Q BPDUs for VLAN 1.
• Process tagged PVST BPDUs for VLANs 2, 3, and 4.
• Drop untagged PVST BPDUs for VLAN 1.
Untagged port using VLAN 2 as port native VLAN
Figure 155 shows an example in which a port Port Native VLAN is not VLAN 1. In this case, VLAN 1
uses tagged frames and VLAN 2 uses untagged frames.
FIGURE 155 Port Native VLAN 2 for Untagged BPDUs
To implement this configuration, enter the following commands.
Commands on the Brocade Device
Brocade(config)#default-vlan-id 4000
Brocade(config)#vlan 1
Brocade(config-vlan-1)#tagged ethernet 1/1
Brocade(config-vlan-1)#exit
Brocade(config)#vlan 2
Brocade(config-vlan-2)#tagged ethernet 1/1
Brocade(config-vlan-2)#exit
Port3/2
Port1/1
Untagged IEEE BPDU for VLAN 1
Tagged PVST BPDU for VLAN 1
Untagged PVST BPDUs for VLAN 2
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