KB.15.15

Example 95 BPDU protection enabled at the network edge

PVST protection and filtering

NOTE: These options are available for switches that support the MSTP protocol only. They are

not supported for switches running RSTP.

PVST protection

If an HP switch in the core of a network receives Per Vlan Spanning Tree (PVST) BPDUs and forwards

the unrecognized PVST BPDUs on to MSTP-only switches, those switches then disconnect themselves

from the network. This can create instability in the network infrastructure.

When the PVST protection feature is enabled on a port and a PVST BPDU is received on that port,

the interface on which the PVST BPDU arrived is shut down, which isolates the sending switch from

the rest of the network. An event message is logged and an SNMP notification trap is generated.

The errant BPDU counter hpSwitchStpPortErrantBpduCounter is incremented. The PVST

protection feature is enabled per-port.

Figure 19 PVST switch being isolated after sending a PVST BPDU

NOTE: This is similar to the BPDU Guard feature where BPDU protection is applied to edge ports

connected to end user devices that do not run STP. If STP BPDU packets are received on a protected

port, the feature will disable that port and alert the network manager via an SNMP trap.

128 Multiple instance spanning tree operation