Administration of the Avaya G350 Media Gateway - Avaya Support

Configuring spanning treePort rolesAt the center of RSTP — specifically as an improvement over STP (802.1d) — are the roles thatare assigned to the ports. There are four port roles:●●●Root port — port closest to the root bridgeDesignated port — corresponding port on the remote bridge of the local root portAlternate port — an alternate route to the root● Backup port — an alternate route to the network segmentThe RSTP algorithm usually makes it possible to change port roles rapidly through its fasttopology change propagation mechanism. For example, a port in the blocking state can beassigned the role of alternate port. When the backbone of the network fails the port can rapidlybe changed to forwarding.Whereas the STA passively waited for the network to converge before turning a port into theforwarding state, RSTP actively confirms that a port can safely transition to forwarding withoutrelying on any specific, programmed timer configuration.RSTP provides a means of fast network convergence after a topology change. It does this byassigning different treatments to different port types. The port types and the treatment theyreceive follow:●●Edge ports — Setting a port to edge-port admin state indicates that this port is connecteddirectly to end stations that cannot create bridging loops in the network. These portstransition quickly to forwarding state. However, if BPDUs are received on an Edge port, it’soperational state will be changed to non-edge-port and bridging loops will be avoided bythe RSTP algorithm. The default admin state of 10/100 M ports is edge-port.Use the set port edge admin state command, followed by the module and portnumber, or a range of port numbers, to specify whether or not a port is considered an edgeport. For example, the following command specifies that ports 5 to 13 on module 4 are edgeports:G350-001(super)# set port edge admin state 4/5-13 edge-portThe following command specifies that port 6 on module 6 is not an edge port:G350-001(super)# set port edge admin state 6/6 non-edge-portUse the show port edge state command, followed by the module and port number, todisplay the edge state of the specified port. Use this command without specifying a modulenumber or port to display the edge state of all ports.You must manually configure uplink and backbone ports to be non-edge ports, using theset port edge admin state command.Issue 3 January 2005 145