ZyXEL Communications ES-3148 Series - Manual (Page 109)

Chapter 11 Spanning Tree Protocol
ES-3148 User’s Guide
109
11.1.3 STP Port States
STP assigns five port states to eliminate packet looping. A bridge port is not allowed to go
directly from blocking state to forwarding state so as to eliminate transient loops.
11.1.4 Multiple RSTP
MRSTP (Multiple RSTP) is ZyXEL’s proprietary feature that is compatible with RSTP and
STP. With MRSTP, you can have more than one spanning tree on your Switch and assign
port(s) to each tree. Each spanning tree operates independently with its own bridge
information.
In the following example, there are two RSTP instances (MRSTP 1 and MRSTP2) on switch
A.
To set up MRSTP, activate MRSTP on the Switch and specify which port(s) belong to which
spanning tree.
"
Each port can belong to one STP tree only.
Figure 45 MRSTP Network Example
Table 25 STP Port States
PORT STATE DESCRIPTION
Disabled STP is disabled (default).
Blocking Only configuration and management BPDUs are received and processed.
Listening All BPDUs are received and processed.
Note: The listening state does not exist in RSTP.
Learning All BPDUs are received and processed. Information frames are submitted to the
learning process but not forwarded.
Forwarding All BPDUs are received and processed. All information frames are received and
forwarded.