Rockwell Automation Ethernet Design Considerations Reference Manual - Manual (Page 48)

48 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Chapter 3 Ethernet Infrastructure Features
Spanning Tree Protocol (STP) and Rapid STP (RSTP)
Spanning Tree Protocol (STP) prevents loops on the network that occur when
there is more than one open path active at once on the network. The convergence
rate can take up to 50 seconds.
Rapid Spanning Tree Protocol (RSTP) is designed for faster network
convergence and eliminates the forwarding delay on point-to-point links by using
explicit handshaking protocol. The convergence rate is significantly faster than
STP:
• Only standard protocol for network resiliency—IEEE 802.1D
• Built into Stratix 8000 and Stratix 8300 switches
• Requires redundant star or ring topology
• Provides alternate path in case of failures, avoiding loops
• Unmanaged switches do not support STP or RSTP, or any other resiliency
protocol
Catalyst 3750 Switch Stack
Stratix 8000
Access Switches
F = Forwarding
B = Blocking
B
Distribution Switches
F B F