Rockwell Automation 1783-Mxxx Stratix 8000 and 8300 Ethernet Managed Switches User Manual - Manual (Page 77)

Rockwell Automation Publication 1783-UM003I-EN-P - March 2014 77
Switch Software Features Chapter 3
• No-neighbor—This port is a secondary edge port connected to a
non-REP switch. The no-neighbor edge ports contain all properties of
regular edge ports. These ports enable the construction of a REP ring
containing a switch that does not support REP protocol.
• None—This port is not part of the REP segment.
REP and STP can coexist on the same switch, but not on the same port. REP
does not interact with STP. For example, if a port is configured as a REP port,
STP is disabled on that port. STP bridge protocol data units (BPDUs) are not
accepted on or sent from segment ports REP ports. However, adjacent REP and
STP rings or domains can share a common link. This common link can be used
for passing REP and STP date plane traffic, or for the STP control plane traffic.
The following figure shows an example of a segment consisting of six ports spread
across four switches. Ports E1 and E2 are configured as edge ports. When all
ports are operational (as in the segment on the left), a single port is blocked,
shown by the diagonal line. When there is a failure in the network, as shown in
the diagram on the right, the blocked port returns to the forwarding state to
minimize network disruption.
REP Open Segment
The segment shown below is an open segment; there is no connectivity between
the two edge ports. The REP segment cannot cause a bridging loop and it is safe
to connect the segment edges to any network. All hosts connected to switches
inside the segment have two possible connections to the rest of the network
through the edge ports, but only one connection is accessible at any time. If a
failure causes a host to be unable to access its usual gateway, REP unblocks all
ports to ensure that connectivity is available through the other gateway.
In Figure 11 , E1 or E2 can be configured as the primary edge port.
Figure 11 - Example of REP Open Segment
E2 E1 E2 E1
E1 Edge port
Blocked port
Link failure
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