Ether Bridge
Use the Ether Bridge > Spanning Trees subtab to view and modify Ether Bridge spanning tree parameters. The ONS node operates Spanning Tree Protocol (STP) according to IEEE 802.1D when an Ethernet card is installed. The E-Series cards support common STPs on a per-circuit basis up to a total of eight STP instances. They do not support per-VLAN STP. In single-card mode, STP can be disabled or enabled on a per-circuit basis during circuit creation. Disabling STP will preserve the number of available STP instances. You can create Ethernet circuits from one E-Series Ethernet card to another in unstitched, point-to-point mode within a single node, but you cannot enable STP on these circuits.
STP operates over all packet-switched ports including Ethernet and STM-N ports. On Ethernet ports, STP is enabled by default but can be disabled. You can also disable or enable STP on a circuit-by-circuit basis on unstitched Ethernet cards in a point-to-point configuration. However, turning off STP protection on a circuit-by-circuit basis means that the ONS network is not protecting the Ethernet traffic on this circuit, and the Ethernet traffic must be protected by another mechanism in the Ethernet network. On STM-N interface ports, the ONS node activates STP by default, and STP cannot be disabled.
The Ethernet card can enable STP on the Ethernet ports to create redundant paths to the attached Ethernet equipment. STP connects cards so equipment and facilities are protected against failure.
Default STP parameters are appropriate for most situations. Contact the Cisco Technical Support before you change the default STP parameters.