BigIron RX Series Configuration Guide 31953-1001810-01Chapter12Configuring Spanning Tree ProtocolIn this chapter• IEEE 802.1D Spanning Tree Protocol (STP) . . . . . . . . . . . . . . . . . . . . . . . . . 319• IEEE Single Spanning Tree (SSTP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330• PVST/PVST+ compatibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332• SuperSpan™ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337IEEE 802.1D Spanning Tree Protocol (STP)The device supports Spanning Tree Protocol (STP) as described in the IEEE 802.10-1998specification. STP eliminates Layer 2 loops in networks, by selectively blocking some ports andallowing other ports to forward traffic, based on configurable bridge and port parameters. STPalso ensures that the least cost path is taken when multiple paths exist between ports or VLANs. Ifthe selected path fails, STP searches for and then establishes an alternate path to prevent or limitretransmission of data.NOTEThe total number of supported STP, RSTP, or MSTP indices is 128.Enabling or disabling STPSTP is disabled by default on the device. Thus, new VLANs you configure on the device have STPdisabled by default. Table 69 lists the default STP states for the device.By default, each VLAN on a BigIron RX runs a separate spanning tree instance. Each device hasone VLAN (VLAN 1) by default that contains all of its ports. However, if you configure additionalport-based VLANs on a device, then each of those VLANs on which STP is enabled and VLAN 1 allrun separate spanning trees.You can enable or disable STP on the following levels:• Globally – Affects all VLANs on the device.TABLE 69 Default STP statesDevice type Default STP type Default STP state Default STP state of newVLANsdevice Brocade’s multiple instances ofspanning treeDisabled Disabled
