3com S7906E 설치 설명서

 

1-33 

 shows the rapid state transition mechanism on MSTP designated ports. 

Rapid state transition of an MSTP designated port  

 

 

 shows rapid state transition of an RSTP designated port.  

Rapid state transition of an RSTP designated port  

Root port
Designated port

Root port blocks other non-
edge ports, changes to 
forwarding state and sends 
Agreement to upstream device 

Upstream device

Downstream device

Proposal for rapid transition

Agree

ment

Designated port 
changes to 
forwarding state

 

 

If the upstream device is a third-party device, the rapid state transition implementation may be limited. 
For example, when the upstream device uses a rapid transition mechanism similar to that of RSTP, and 
the downstream device adopts MSTP and does not work in RSTP mode, the root port on the 
downstream device receives no agreement packet from the upstream device and thus sends no 
agreement packets to the upstream device. As a result, the designated port of the upstream device fails 
to transit rapidly and can only change to the forwarding state after a period twice the Forward Delay. 

In this case, you can enable the No Agreement Check feature on the downstream device’s port to 
enable the designated port of the upstream device to transit its state rapidly. 

z

 

A device is connected to a third-party upstream device supporting MSTP via a point-to-point link. 

z

 

Configure the same region name, revision level and VLAN-to-instance mappings on the two 
devices, thus assigning them to the same region. 

To make the No Agreement Check feature take effect, enable it on the root port.  

Follow these steps to configure No Agreement Check: