3Com 4007, Implementation Manual, Page: 168 / 684

168 C
HAPTER
9: B
RIDGE
-W
IDE AND
B
RIDGE
P
ORT
P
ARAMETERS
Port Forwarding
Behavior
Table 40 summarizes the forwarding behavior of bridge ports based on
the bridge and port STP states:
When STP is removed from the port but is enabled for the bridge, the
port is invisible to STP but can forward frames. Removing the port from
STP is useful if you have an edge switch device that is connected to end
stations (such as PCs) that are frequently turned on and off.
Routing Over
Blocked STP Ports
On a Multilayer Switching Module, you can elect to route certain
specified traffic and bridge (using STP) other traffic simultaneously. To
route packets from ports that are blocked by STP, you can configure a
VLAN port to
ignore the STP mode. For more information, see the VLAN
chapter in this guide or see the command
bridge vlan stpMode
in the
Switch 4007 Command Reference Guide
.
STP Compatible with
Trunking
You can enable STP on the same module and ports on which you
configure trunks. STP understands that a trunk is one logical bridge port.
In fact, you may find it useful to configure a backup trunk that STP places
in the blocking state. Of course, a trunk itself has resilient properties in
point-to-point connections, thus even if you do not enable STP, you can
still gain a measure of resiliency in your network topology. See the
Trunking chapter in this guide for more information.
Table 40 Port Forwarding Behavior Depends on Bridge and Port STP States
Bridge STP State Port STP State
Port Participates
in STP? Port Forwards
Frames?
Disabled Disabled No Yes, if link state is up.
Enabled No Yes, if link state is up.
Removed No Yes, if link state is up.
Enabled Disabled No No
Enabled Yes Determined by STP
provided that the link
state is up.
Removed No Yes, if link state is up.