Siemens S323 User Manual

User Manual                                                                               UMN:CLI 
SURPASS hiD 6615 S223/S323 R1.5 

A50010-Y3-C150-2-7619                                                                         205 

STP or RSTP is configured on network where Loop can be created. However, RSTP is 
more rapidly progressed than STP at the stage of reaching to the last topology. This sec-
tion describes how the RSTP more improved than STP works. It contains the below sec-
tions. 

•

 Port 

States 

•

 BPDU 

Policy 

•

 

Rapid Network Convergence 

•

 

Compatibility with 802.1d. 

 

RSTP defines port states as discarding, learning, and forwarding. Blocking of 802.1d and 
listening is combined into discarding. Same as STP, root port and designated port are de-
cided by port state. But a port in blocking state is divided into alternate port and backup 
port. Alternate port means a port blocking BPDUs of priority of high numerical value from 
other switches, and backup port means a port blocking BPDUs of priority of high numeri-
cal value from another port of same equipment. 

Switch B

Switch A

Switch C

 

Alternate Port and Backup port 

 

The difference of between alternate port and backup port is that alternate port can alter-
nate path of packet when there is a problem between Root switch and SWITCH C but 
Backup port cannot provide stable connection in that case.