1-41 
Some other manufacturers' switches adopt proprietary spanning tree protocols that are similar to RSTP 
in the way to implement rapid transition on designated ports. When a switch of this kind operating as the 
upstream switch connects with a 3com switch running MSTP, the upstream designated port fails to 
change its state rapidly. 
The rapid transition feature is developed to resolve this problem. When a 3com switch running MSTP is 
connected in the upstream direction to another manufacturer's switch running proprietary spanning tree 
protocols, you can enable the rapid transition feature on the ports of the 3com switch operating as the 
downstream switch. Among these ports, those operating as the root ports will then send agreement 
packets to their upstream ports after they receive proposal packets from the upstream designated ports, 
instead of waiting for agreement packets from the upstream switch. This enables designated ports of 
the upstream switch to change their states rapidly. 
Configuring Rapid Transition 
Configuration prerequisites 
As shown in Figure 1-8, a 3com switch is connected to another manufacturer's switch. The former 
operates as the downstream switch, and the latter operates as the upstream switch. The network 
operates normally. 
The upstream switch is running a proprietary spanning tree protocol that is similar to RSTP in the way to 
implement rapid transition on designated ports. Port 1 is the designated port. 
The downstream 3com switch is running MSTP. Port 2 is the root port. 
Figure 1-8 Network diagram for rapid transition configuration 
 
 
Configuration procedure 
1)  Configure the rapid transition feature in system view 
Follow these steps to configure the rapid transition feature in system view: 
To do...  Use the command...  Remarks 
Enter system view 
system-view 
— 
Enable the rapid transition 
feature 
stp interface interface-type 
interface-number 
no-agreement-check 
Required 
By default, the rapid transition 
feature is disabled on a port. 
 
2)  Configure the rapid transition feature in Ethernet port view 
Follow these steps to configure the rapid transition feature in Ethernet port view: