Cabletron Systems 2.2 Manuel D’Utilisation

Source Route Configuration

2-61

Bridging

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 

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.

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 

 window, 

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:

¥

 (participating in frame relay).