Rockwell Automation 1783-BMxxx Stratix 5700 Ethernet Managed Switches User Manual - Manual (Page 109)

Rockwell Automation Publication 1783-UM004E-EN-P - June 2014 109
Switch Software Features Chapter 3
REP Ring Segment
The segment shown in Figure 7 , 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 the following figure, E1 or E2 can be configured as the primary edge port.
Figure 7 - Ring Segment Example
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 support ongoing 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 cannot support REP, as shown
in
Figure 8 . 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.
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E1 E2