Rockwell Automation 1783-Mxxx Stratix 8000 and 8300 Ethernet Managed Switches User Manual - Manual (Page 76)

76 Rockwell Automation Publication 1783-UM003I-EN-P - March 2014
Chapter 3 Switch Software Features
CIP Sync Time
Synchronization (Precision
Time Protocol) The IEEE 1588 standard defines a protocol called Precision Time Protocol
(PTP) that enables precise synchronization of clocks in measurement and control
systems. We refer to this as CIP Sync time synchronization. The clocks are
synchronized over the EtherNet/IP communication network. PTP enables
systems that include clocks of various precision, resolution, and stability to
synchronize. PTP generates a Master-Slave relationship among the clocks in the
system. All clocks ultimately derive their time from a clock selected as the
Grandmaster clock.
Resilient Ethernet Protocol The Resilient Ethernet Protocol (REP) provides an alternative to Spanning Tree
Protocol (STP) to control network rings and loops, handle link failures, and
improve convergence time. REP controls a group of ports connected in a
segment, ensures that the segment does not create any bridging loops, and
responds to link failures within the segment. REP provides a basis for
constructing more complex networks and supports VLAN load balancing.
REP is a segment protocol. One REP segment is a chain of ports connected to
each other and configured with a segment ID. Each segment consists of standard
(transit) segment ports and two user-configured edge ports. A switch can have no
more than two ports that belong to the same segment, and each segment port can
have only one external neighbor. A segment can go through a shared medium, but
on any link only two ports can belong to the same segment. REP is supported
only on Layer 2 trunk interfaces. Selecting the Switch for Automation port role
enables Layer 2 trunking. REP is supported on EtherChannels, but not on an
individual port that belongs to an EtherChannel.
You can construct almost any type of network based on REP segments. REP also
supports VLAN load-balancing, controlled by the primary edge port but
occurring at any port in the segment.
These types of REP ports are available in the Device Manager Web interface:
• Primary—This port is a primary edge port. This port always participates in
VLAN load balancing in the REP segment.
• Edge—This port is a secondary edge port. It also participates in VLAN
load balancing in the REP segment. Edge ports are termination points of a
REP segment. You must configure two edge ports, including one primary
edge port, for each REP segment. Entering edge without primary
configures the port as a secondary edge port. Primary and secondary edge
ports must be configured even if support of VLAN balancing is not
required.
• Transit—This port is a non-edge port in the REP segment.
• No-neighbor Primary—This port is a primary edge port connected a non-
REP switch.