Pvst/Pvst+ Compatibility - Earlier Than 07.6.01B - HP ProCurve 9304M Installation And Configuration Manual

In the configuration above, all PVST BPDUs associated with VLAN 1 would be discarded. Since IEEE BPDUs
associated with VLAN 1 are untagged, they are discarded because the ports in VLAN 1 are tagged. Effectively,
the BPDUs are never processed by the Spanning Tree Protocol. STP assumes that there is no better bridge on
the network and sets the ports to FORWARDING. This could cause a Layer 2 loop.
The following configuration is correct:
HP9300(config)# default-vlan-id 1000
HP9300(config)# vlan 1
HP9300(config-vlan-1)# tagged ethernet 1/1 to 1/2
HP9300(config-vlan-1)# exit
HP9300(config)# interface ethernet 1/1
HP9300(config-if-1/1)# pvst-mode
HP9300(config-if-1/1)# dual-mode
HP9300(config-if-1/1)# exit
HP9300(config)# interface ethernet 1/2
HP9300(config-if-1/2)# pvst-mode
HP9300(config-if-1/2)# dual-mode
HP9300(config-if-1/2)# exit
Setting the ports as dual-mode ensures that the untagged IEEE 802.1Q BPDUs reach the VLAN 1 instance.
PVST/PVST+ Compatibility – Earlier Than 07.6.01b
HP devices that are configured to support a separate spanning tree in each port-based VLAN can interoperate
with Cisco devices that are running Per VLAN Spanning Tree (PVST) or PVST+, Cisco proprietary STP
implementations that support separate spanning trees in each port-based VLAN.
An HP device configured to run a separate spanning tree in each port-based VLAN automatically enables PVST/
PVST+ support on a port if that port receives an STP BPDU with PVST/PVST+ format. You also can enable
PVST/PVST+ support statically as well as display PVST/PVST+ information for each port.
The information in this section is for reference. If you are running PVST/PVST+ on the Cisco devices and the
default support for separate spanning trees in each VLAN on the HP devices, then no configuration is necessary
for the devices to share spanning tree information.
NOTE: If you plan to use the PVST/PVST+ support, do not use VLAN 1. PVST+ uses VLAN 1 as a single STP
broadcast domain and thus uses a different BPDU format than for other VLANs.
PVST
Each spanning tree (that is, each instance of STP) has one device called the root bridge. The root bridge is the
control point for the spanning tree, and sends STP status and topology change information to the other devices in
the spanning tree by sending BPDUs to the other devices. The other devices forward the BPDUs as needed.
The format of an STP BPDU differs depending on whether it is a Cisco PVST BPDU or an HP BPDU. HP and
Cisco devices also can support single STP BPDUs, which use another format.
• An HP device configured with a separate spanning tree in each VLAN sends BPDUs in standard IEEE
802.1D format, but includes a proprietary four-byte tag. The tag identifies the VLAN the BPDU is for.
• A Cisco device configured for PVST sends the BPDUs to multicast MAC address 01-00-0C-CC-CC-CD. If
the device is configured for PVST+, then the device sends BPDUs for all VLANs except VLAN 1 to 01-00-0C-
CC-CC-CD. The device sends BPDUs in VLAN 1 to 01-80-C2-00-00-00, the single STP address (see below
and "PVST+").
• An HP device configured for single STP (IEEE 802.1Q) sends untagged BPDUs to the well-known STP MAC
address 01-80-C2-00-00-00.
NOTE: Cisco devices can be configured to interoperate with devices that support IEEE 802.1Q single STP, but
the devices cannot be configured to run single STP.
Configuring Spanning Tree Protocol (STP) and Advanced STP Features
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