Management Guide - Kamery IP

Spanning Tree Algorithm Configuration3MSTP – When using STP or RSTP, it may be difficult to maintain a stable pathbetween all VLAN members. Frequent changes in the tree structure can easilyisolate some of the group members. MSTP (which is based on RSTP for fastconvergence) is designed to support independent spanning trees based on VLANgroups. Using multiple spanning trees can provide multiple forwarding paths andenable load balancing. One or more VLANs can be grouped into a Multiple SpanningTree Instance (MSTI). MSTP builds a separate Multiple Spanning Tree (MST) foreach instance to maintain connectivity among each of the assigned VLAN groups.MSTP then builds a Internal Spanning Tree (IST) for the Region containing allcommonly configured MSTP bridges.An MST Region consists of a group of interconnected bridges that have the sameMST Configuration Identifiers (including the Region Name, Revision Level andConfiguration Digest – see “Configuring Multiple Spanning Trees” on page 3-212).An MST Region may contain multiple MSTP Instances. An Internal Spanning Tree(IST) is used to connect all the MSTP switches within an MST region. A CommonSpanning Tree (CST) interconnects all adjacent MST Regions, and acts as a virtualbridge node for communications with STP or RSTP nodes in the global network.MSTP connects all bridges and LAN segments with a single Common and InternalSpanning Tree (CIST). The CIST is formed as a result of the running spanning treealgorithm between switches that support the STP, RSTP, MSTP protocols.3-195