Rockwell Automation 1783-Mxxx Stratix 8000 and 8300 Ethernet Managed Switches User Manual - Manual (Page 78)

78 Rockwell Automation Publication 1783-UM003I-EN-P - March 2014
Chapter 3 Switch Software Features
REP Ring Segment
The segment shown in the following figure, with both edge ports on the same
switch, is a ring segment. In this configuration, there is connectivity between the
edge ports through the segment. With this configuration, you can create a
redundant connection between any two switches in the segment.
In Figure 12 , E1 or E2 can be configured as the primary edge port.
Figure 12 - Example of REP Ring Segment
REP segments have these characteristics:
• If all ports in the segment are operational, one port (referred to as the
alternate port) is in the blocked state for each VLAN.
• If VLAN load balancing is configured, two ports in the segment control
the blocked state of VLANs.
• If one or more ports in a segment is not operational, causing a link failure,
all ports forward traffic on all VLANs to ensure connectivity.
• In case of a link failure, the alternate ports are unblocked as quickly as
possible. When the failed link comes back up, a logically blocked port per
VLAN is selected with minimal disruption to the network.
Access Ring Topologies
In access ring topologies, the neighboring switch does not always support REP, as
shown in the following figure. In this case, you can configure the non-REP facing
ports (E1 and E2) as edge no-neighbor ports. These ports inherit all properties of
edge ports, and you can configure them the same as any edge port, including
configuring them to send STP or REP topology change notices to the
aggregation switch. In this case the STP topology change notice (TCN) that is
sent is a multiple spanning-tree (MST) STP message.
E2 E1
201889