Netgear XCM8806 Chassis User Manual - Page 565

NETGEAR 8800 User Manual MSTP Region 1 and MSTP Region 2 are connected to the CIST root through directly connected ports, identified as master ports. The bridge with ID 100 connects to the CIST root through Region 1, Region 2, or segment B. For this bridge, either Region 1 or Region 2 can be the designated region or segment B can be the designated segment. The CIST BPDUs egressing from the boundary ports carry the CIST regional root as the designated bridge. This positions the entire MSTP region as one virtual bridge. The CIST controls the port roles and the state of the boundary ports. A master port is always forwarding for all CIST and MSTI VLANs. If the CIST sets a boundary port to the discarding state, the CIST blocks traffic for all VLANs mapped to it and the MSTIs within that region. Each MSTI blocks traffic for their member VLANs and puts their internal ports into the forwarding or blocking state depending on the MSTI port roles. For more information about port states, see MSTP Port States on page 565. MSTP Port Roles MSTP uses the same port roles as RSTP (Root, Designated, Alternate, and Backup), as described in Table 52 on page 546. In addition to those port roles, MSTP introduces a new port role: Master. A Master port is the port that connects an MSTI to the CIST root. MSTP Port States MSTP uses the same port states as RSTP (Listening, Learning, Forwarding, and Blocking). In the NETGEAR MSTP implementation, the listening state is not truly implemented as FDB learning cannot be done when the port is not in the forwarding state. Ports in the blocking state listen but do not accept ingress traffic, perform traffic forwarding, or learn MAC source address; however, the port receives and processes BPDUs. For more information about all of the STP port states, see STP States on page 531. MSTP Link Types MSTP uses the same link types as STP and RSTP, respectively. In an MSTP environment, configure the same link types for the CIST and all MSTIs. For more information about the link types, see Link Types on page 546. MSTP Edge Safeguard You can configure edge safeguard for loop prevention and detection on an MSTP edge port. For more information see Configuring Edge Safeguard on page 548. Note: In MSTP, configuring edge safeguard at CIST will be inherited in all MSTI.  In MSTP, an edge port needs to be added to a CIST before adding it to an MSTI. Chapter 18. STP | 565