IEEE Std 802.1Qca-2015 pdf free download – IEEE Standard for Local and metropolitan area networks- Bridges and Bridged Networks Amendment 24: Path Control and Reservation.
The Bridge’s forwarding processes constrain the potential path for each user data frame to a single spanning tree. A Bridge that uses RSTP or STP allocates all frames to a single CST. An MST or SPT Region (13.8, 27.4.1) comprises the transitive closure of Bridges that use MSTP or SPB and that agree on the allocation of frames with a given VID to a given subtree within the region. That subtree can be an MSTI, a SPT, an Explicit Tree (ET), or the IST that is the logical continuation of the CST through the region. Interoperability between MST and SPT Bridges and SST Bridges, and between differently configured MST/SPT Bridges, is achieved by allocating all frames to the CST at region boundaries. Thus the spanning tree for a given frame can comprise subtrees of the CST together with an MSTI or SPT within each region. Frames with different VIDs can be assigned to the same or to different trees and subtrees within a region. NOTE—In a stable network, the MSTP and SPB algorithms verify that each MST/SPT Region is fully connected internally. However, if the CST Root lies outside the region, the region can be partitioned temporarily as necessary to prevent external connectivity between Bridge Ports at the region boundary from creating a loop.
A given region of the network can be an MST Region, an SPT Region, or both, but the protocol mechanisms that verify connectivity internal to the region require that regions do not overlap or subset other regions.
8. Principles of Bridge operation
8.4 Active topologies, learning, and forwarding Change the 12th paragraph of 8.4 as follows: If a B-VLAN is supported by SPBM (Clause 27), the frame is assigned a B-VID value that identifies the frame as subject to SPBM and identifies the B-VLAN and the SPT Set (Clause 3). The SPT is identified (from among those in that set) by the source address of the frame (B-SA) which identifies the SPT root. When ISIS-SPB sets forwarding True for that SPT, a Dynamic Filtering Entry for that B-VID, source address tuple is included in the Filtering Database so that it passes the active topology enforcement check (8.6.1). An individual destination address identifies the SPT that is rooted at that destination and belongs to the SPT Set identified by the VID. If relaxed ingress checking (45.3.1) is supported, then a MAC Address Registration Entry is included in the Filtering Database for that VID, individual destination address tuple if there is any source whose path to the destination in that SPT is via the given Bridge. The Port Map of those MAC Address Registration entries comprises only the ports that are upstream for a given individual destination address (45.3.1). If a B-VLAN is supported by SPBM, learning is disabled for all frames for that B-VID.IEEE Std 802.1Qca pdf download.