Administration of the Avaya G350 Media Gateway - Avaya Support

Configuring advanced switchingThe Spanning Tree Algorithm requires five values to derive the spanning tree topology. Theseare:●●●●A multicast address specifying all bridges on the extended network. This address ismedia-dependent and is automatically determined by the software.A network-unique identifier for each bridge on the extended network.A unique identifier for each bridge/LAN interface (a port).The relative priority of each port.● The cost of each port.After these values are assigned, bridges multicast and process the formatted frames (calledBridge Protocol Data Units, or BPDUs) to derive a single, loop-free topology throughout theextended network. The bridges exchange BPDU frames quickly, minimizing the time thatservice is unavailable between hosts.Spanning tree per portSpanning tree can take up to 30 seconds to open traffic on a port. This delay can causeproblems on ports carrying time-sensitive traffic. You can therefore enable or disable spanningtree in the G350 on a per-port basis to minimize this effect.Rapid Spanning Tree Protocol (RSTP)About the 802.1w (RSTP) standardThe enhanced feature set of the 802.1w standard includes:● Bridge Protocol Data Unit (BPDU) type 2●●●●New port roles: Alternate port, Backup portDirect handshaking between adjacent bridges regarding a desired topology change (TC).This eliminates the need to wait for the timer to expire.Improvement in the time it takes to propagate TC information. Specifically, TC informationdoes not have to be propagated all the way back to the Root Bridge (and back) to bechanged.Origination of BPDUs on a port-by-port basis144 Administration of the Avaya G350 Media Gateway