Enabling Pvst+ Extend System Id; Pvst+ Sample Configurations - Dell Force10 Z9000 Configuration Manual

Networking OS from executing this action, use the no spanning-tree pvst err-disable cause invalid-pvst-
bpdu command. After you configure this command, if the port receives a PVST+ BPDU, the BPDU is dropped and the port remains
operational.

Enabling PVST+ Extend System ID

In the following example, ports P1 and P2 are untagged members of different VLANs. These ports are untagged because the hub is
VLAN unaware. There is no data loop in this scenario; however, you can employ PVST+ to avoid potential misconfigurations.
If you enable PVST+ on the Dell Networking switch in this network, P1 and P2 receive BPDUs from each other. Ordinarily, the Bridge
ID in the frame matches the Root ID, a loop is detected, and the rules of convergence require that P2 move to blocking state
because it has the lowest port ID.
To keep both ports in a Forwarding state, use extend system ID. Extend system ID augments the bridge ID with a VLAN ID to
differentiate BPDUs on each VLAN so that PVST+ does not detect a loop and both ports can remain in a Forwarding state.
Figure 93. PVST+ with Extend System ID
• Augment the bridge ID with the VLAN ID.
PROTOCOL PVST mode
extend system-id
Example of Viewing the Extend System ID in a PVST+ Configuration
Dell(conf-pvst)#do show spanning-tree pvst vlan 5 brief
VLAN 5
Executing IEEE compatible Spanning Tree Protocol
Root ID Priority 32773, Address 0001.e832.73f7
Root Bridge hello time 2, max age 20, forward delay 15
Bridge ID Priority 32773 (priority 32768 sys-id-ext 5), Address 0001.e832.73f7
We are the root of Vlan 5
Configured hello time 2, max age 20, forward delay 15

PVST+ Sample Configurations

The following examples provide the running configurations for the topology shown in the previous illustration.
Example of PVST+ Configuration (R1)
interface TenGigabitEthernet 1/22
no ip address
574
Per-VLAN Spanning Tree Plus (PVST+)