Configuration Guide MSTP Configuration
Figure-3
There are three port states for every port to indicate whether the data packet is
forwarded and control the topology of the whole spanning tree.
Discarding: Neither forward the received frame nor learn about the source
Mac address.
Learning: Do not forward the received frame, but learn about the source
Mac address, so it is a transitional status.
Forwarding: Both forward the received frame and learn about the source
Mac address.
For the stable network topology, only the root port and designated port can be
the forwarding status, while other ports are only in the discarding status.
Generating a Network Topology Tree (Typical Application Solution)
We now describe how the STP and RSTP protocols span a tree-type structure
by the mixed network topology. As shown in Figure 4, the bridge IDs of Switches
A, B and C are assumed in the ascending order. Namely, Switch A presents the
highest priority. There is the 1000M link between switch A and switch B, and the
100M link between switch A and switch C, while it is the 10M link between
switch B and switch C. Switch A acts as the backbone switch of this network
and implements the link redundancy for both Switch B and Switch C. Obviously,
broadcast storm would occur if all these links are active.