Dell PowerConnect 5212 System User's Manual page 51

Console(config)#
Port and Trunk Settings
You can configure RSTP attributes for specific interfaces, including port priority, path cost, link type, and edge port. You may use a different priority or path cost
for ports of the same media type to indicate the preferred path, link type to indicate a point-to-point connection or shared-media connection, and edge port to
indicate if the attached device can support fast forwarding. (References to "ports" in this section mean "interfaces," which includes both ports and trunks.)
In the Port Settings page, you can specify Spanning Tree parameters for each port. For each port number listed in the Port column, the following information
is available:
State — Displays current state of this port within the Spanning Tree:
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Broken — No valid link on the port.
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Discarding — The port receives STA configuration messages, but does not forward packets.
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Learning— The port has transmitted configuration messages for an interval set by the Forward Delay parameter without receiving contradictory
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information. The port address table is cleared, and the port begins learning addresses.
Forwarding — The port forwards packets, and continues learning addresses.
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Designated Cost — The cost for a packet to travel from this port to the root in the current Spanning Tree configuration (the slower the media, the
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higher the cost)
Designated Bridge — The priority and MAC address of the device through which this port must communicate to reach the root of the Spanning Tree
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Designated Port — The priority and number of the port on the designated bridging device through which this switch must communicate with the root of
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the Spanning Tree
Trunk — Indicates whether the port is configured as a trunk member
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The Port Settings page also contains the following editable fields:
Priority — Defines the priority used for this port in the Spanning Tree Protocol. If the path cost for all ports on a switch is the same, the port with the
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highest priority (i.e., lowest value) will be configured as an active link in the Spanning Tree. This makes a port with higher priority less likely to be
blocked if the Spanning Tree Protocol is detecting network loops. Where more than one port is assigned the highest priority, the port with lowest
numeric identifier will be enabled. (Default: 128; Range: 0-240, in steps of 16)
Path Cost — This parameter is used by the STP to determine the best path between devices. Therefore, lower values should be assigned to ports
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attached to faster media, and higher values assigned to ports with slower media. (Path cost takes precedence over port priority.)>
Range:
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Ethernet — 200,000-20,000,000
Fast Ethernet — 20,000-2,000,000
Gigabit Ethernet — 2,000-200,000
Defaults:
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Ethernet — Half duplex: 2,000,000; full duplex: 1,000,000; trunk: 500,000
Fast Ethernet — Half duplex: 200,000; full duplex: 100,000; trunk: 50,000
Gigabit Ethernet — Full duplex: 10,000; trunk: 5,000
NOTICE: When the Path Cost Method is set to short, the maximum path cost is 65,535.
Link Type — The link type attached to this interface. (Default: Auto)
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Point-to-Point — A connection to exactly one other bridge.
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Shared — A connection to two or more bridges.
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Auto — The switch automatically determines if the interface is attached to a point-to-point link or to shared media.
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Edge Port — You can enable this option if an interface is attached to a LAN segment that is at the end of a bridged LAN or to an end node. Since end
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nodes cannot cause forwarding loops, they can pass directly through to the spanning tree forwarding state. Specifying Edge Ports provides quicker
convergence for devices such as workstations or servers, retains the current forwarding database to reduce the amount of frame flooding required to
rebuild address tables during reconfiguration events, does not cause the Spanning Tree to initiate reconfiguration when the interface changes state,
and also overcomes other STP-related timeout problems. However, remember that Edge Port should only be enabled for ports connected to an end-
node device.
Migration — Rechecks the appropriate BPDU format to send on the selected interface. If at any time the switch detects STP BPDUs, including
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Configuration or Topology Change Notification BPDUs, the switch automatically sets the selected interface to forced STP-compatible mode. However, you
can also check this Migration check box to manually recheck the appropriate BPDU format (RSTP or STP-compatible) to send on the selected interfaces.