Allied Telesis AT-S63 - Manual (Page 303)

AT-S63 Management Software Web Browser User’s Guide
Section IV: Spanning Tree Protocols 303
ˆ Point-to-point port
ˆ Edge port
An MSTI-specific parameter can be set on a per MSTI basis. This
means that you can assign a different value to a MSTI-specific
parameter for each spanning tree instance where a port is a member.
These parameters are:
ˆ Internal path cost
ˆ Port priority
When setting an MSTI-specific parameter, use the MSTI List in the
window to select the intended MSTI. It should be noted that the MSTI
List shows all of the spanning tree instances on the switch, and not just
those where the selected port is currently a member. If you select an
MSTI where the port is not a member, you can pre-configure the
parameter in the event you later add the port as a member of the MSTI
through a VLAN assignment.
Port Priority
This parameter is used as a tie breaker when two or more ports are
determined to have equal costs to the regional root bridge. The range
is 0 to 240 in increments of 16. The default value is 8 (priority value is
128). For a list of the increments, refer to Table 6, “Port Priority Value
Increments” on page 278.
Port Internal Path Cost
The port cost of the port if the port is connected to a bridge which is
part of the same MSTP region. The range is 0 to 200,000,000. The
default setting is Auto-detect, which sets port cost depending on the
speed of the port. Table 7 lists the MSTP port cost with Auto Update
when a port is not part of a port trunk.
Table 8 lists the MSTP port costs with Auto Update when the port is
part of a port trunk.
Table 7. MSTP Auto Update Port Internal Path Costs
Port Speed Port Cost
10 Mbps 2,000,000
100 Mbps 200,000
1000 Mbps 20,000
Table 8. MSTP Auto Update Port Trunk Internal Path Costs
Port Speed Port Cost
10 Mbps 20,000
100 Mbps 20,000