Netgear XCM8806 Chassis User Manual - Page 562

NETGEAR 8800 User Manual (10) CIST root bridge A (20) CIST regional root D MSTP E Region 1 = boundary port = master port = MSTI root port F G (50) MSTI (60) regional root Figure 51. Close-Up of MSTP Region 1 EX_168 CIST Root Port The port on the CIST regional root bridge that connects to the CIST root bridge is the CIST root port (also known as the master port for MSTIs). The CIST root port is the master port for all MSTIs in that region, and it is the only port that connects the entire region to the CIST root. If a bridge is both the CIST root bridge and the CIST regional root bridge, there is no CIST root port on that bridge. Enabling the CIST To enable the CIST, use the following command and specify the CIST domain as the : enable stpd {} Multiple Spanning Tree Instances As previously described, multiple spanning tree instances (MSTIs) control the topology inside an MSTP region. An MSTI is a spanning tree domain that operates within and is bounded by a region; an MSTI does not exchange BPDUs with or send notifications to other regions. You identify an MSTI on a per region basis. The MSTI ID does not have any significance outside of its region so you can re-use IDs across regions. An MSTI consists of a group of VLANs, which can share the same network topology. Each MSTI has its own root bridge and a tree spanning its bridges and LAN segments. You must first configure a CIST before configuring any MSTIs in the region. You cannot delete or disable a CIST if any of the MSTIs are active in the system. You can map multiple VLANs to an MSTI; however, multiple MSTIs cannot share the same VLAN. 562 | Chapter 18. STP