17.1.3 Applications

(1) Application of the detection transmission shutdown port

This port type is generally specified for L2 loop detection. As shown by Switches C, D, and E in the figure, specifying lower-level ports as detection-frame-sending-and-port-blocking ports is effective for failures caused by incorrect lower-level connections (see 1, 2, and 3 in the figure).

(2) Applying Detected Outbound Ports

This port type is effective for minimizing the extent of a loop failure when L1 loop detection is used on a switch at the lowest possible level. When a Switch is connected to multiple layers (see Switches C and E in the figure), if a port on the Switch C side is deactivated due to an incorrect connection (2 in the figure), none of the terminals unrelated to the loop failure occurring on Switch E can connect to a higher-level network. This is the reason that using the L2 loop detection functionality in a lower-level Switch (Switch E in the figure) is recommended.

For such cases, specify a port on the Switch C side as the detecting and sending port. This setting allows Switch E to detect loop failures during normal operation, but if the Switch is unable to detect loop failures because L2 loop detection is configured incorrectly, Switch C can detect loop failures instead of being deactivated.

(3) Applying Uplink Ports

Specify an uplink port for ports connected to a higher-level network or for ports that will connect to the core network. This setting ensures connection to the core network because the source port of Switch C enters inactive status in the event of an incorrect connection as described in 4.