Rockwell-automation Ethernet Design Considerations Reference Manual Manual do Utilizador descarregar pdf (Página 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

Distribution Switches

FB F

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Rockwell-automation Ethernet Design Considerations Reference Manual Manual do Utilizador Página 48