Spanning Tree Protocol (Stp) - HP 9304m Installation And Getting Started Manual

Figure 7.5 shows an example of two devices that have the same Layer 2 port-based VLANs configured across
them. Notice that only one of the VLANs requires tagging.
Figure 7.5 VLANs configured across multiple devices
VLAN A
User-configured port-based VLAN

Spanning Tree Protocol (STP)

STP is disabled by default on HP Routing Switches.
Also by default, each port-based VLAN has a separate instance of STP. Thus, when STP is globally enabled,
each port-based VLAN on the device runs a separate spanning tree.
You can enable or disable STP on the following levels:
• Globally – Affects all ports on the device.
NOTE: If you configure a port-based VLAN on the device, the VLAN has the same STP state as the default
STP state on the device. On Routing Switches, new VLANs have STP disabled by default. You can enable or
disable STP in each VLAN separately. In addition, you can enable or disable STP on individual ports.
• Port-based VLAN – Affects all ports within the specified port-based VLAN.
STP is a Layer 2 protocol. Thus, you cannot enable or disable STP for individual protocol VLANs or for IP sub-net,
IPX network, or AppleTalk cable VLANs. The STP state of a port-based VLAN containing these other types of
VLANs determines the STP state for all the Layer 2 broadcasts within the port-based VLAN. This is true even
though Layer 3 protocol broadcasts are sent on Layer 2 within the VLAN.
It is possible that STP will block one or more ports in a protocol VLAN that uses a virtual interface to route to other
VLANs. For IP protocol and IP sub-net VLANs, even though some of the physical ports of the virtual interface are
blocked, the virtual interface can still route so long as at least one port in the virtual interface's protocol VLAN is
not blocked by STP.
VLAN A/B
VLAN A
Configuring Virtual LANs (VLANs)
VLAN B
VLAN A/B VLAN B
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