Cabletron Systems 2.2 manual Bridge Number, Spanning Tree Mode

Bridging

Bridge Number

The Bridge Number uniquely identiÞes a bridge port when more than one bridge is used to span the same two segments. The Bridge Number should be in the range of 0 to 15.

You can use the Set button at the bottom of the window to change the bridge number of the port, as explained in Making and Setting Changes, page 2-62. Current source routing protocols allow a range of 0 to 15 (0ÐF hexadecimal) for the bridge number identiÞer. If no bridge number is assigned to the device, a default value of 1 will appear in this Þeld.

Spanning Tree Mode

Indicates how a port on the device will behave with an incoming single-route broadcast (Spanning Tree ExplorerÑSTE) frame. You can conÞgure this Þeld with the option buttons and checkboxes, or via the MIBTools utility or local management.

This Þeld allows you to conÞgure a Spanning Tree for your network. You can set the Spanning Tree Mode to Auto or Manual using the option buttons. We recommend that all bridges in your network topology have the same setting for Spanning Tree Mode (i.e., all set to Auto or all set to Manual).

Auto	If the Spanning Tree Mode is set to Auto, a port that implements
	the Spanning Tree Algorithm (STA) and is enabled and in the
	forwarding state will accept and relay STE frames onto its
	attached segment.
	Using STA, a bridge port will only forward frames if it is the
	designated port for its attached segment. A port is ÒdesignatedÓ
	for its segment if it has the lowest Root Path Cost of all bridge
	ports attached to that segment. The Root Path Cost is the lowest
	total path cost calculated by adding the costs of each port along
	the path of a frame that traverses the bridge topology from the
	root to that port (including its own path cost).
	If two ports on a segment have equal Root Path Costs, the port on
	the bridge with the highest priority bridge identiÞer (for
	convenience sake, that have the lowest numerical value) will be
	chosen as the root port.
	You can affect Spanning Tree topology by changing the deviceÕs
	bridge priority (Bridge Label) and path cost for its port pair (path
	cost increment) via the Spanning Tree window, page 2-34.
Manual	If the Spanning Tree Mode is set to Manual, you can manually
	conÞgure the bridge to forward STE frames (i.e., manually
	establish a Spanning Tree for STE frames by determining which
	bridge in a parallel series of bridges will forward these frames).

If you set the Spanning Tree Mode to Manual, you can use the Enable or Disable checkboxes to set a portÕs Spanning Tree Enable State to:

¥Enabled (participating in frame relay).

Source Route Configuration 2-61