Ignore Stp Mode; Important Considerations - 3Com corebuilder 3500 Implementation Manual

172 C 9: V
HAPTER IRTUAL

Ignore STP Mode

Important
Considerations
LAN
S
When you use allClosed VLAN mode on your system, you can enable the
system to ignore the Spanning Tree Protocol (STP) mode on a per-VLAN
basis, that is, to ignore STP blocked ports for static protocol-based VLANs
associated with routing interfaces. (When STP detects multiple paths to a
destination, it blocks all but one of the paths.)
If you have configured router port IP interfaces on your system (so that
the system generates router port VLANs owned by the router IP
interfaces), ignore STP mode is automatically enabled and you cannot
disable it.
Ignore STP mode is disabled by default for static VLANs.
You can use this mode only when the system is in allClosed mode.
Ignore STP mode is useful when you have redundant router
connections between systems that have STP enabled. In this situation,
if you want to create multiple VLANs and use one VLAN for routing,
you can configure your system to ignore the STP blocking mode for
that VLAN. This setting avoids disruptions to routing connectivity
based on the STP state.
To disable STP blocking on a per-port basis with allOpen or allClosed
VLANs, use the bridging option (
Administration Console). See Chapter 7 for bridging information.
Ignore STP mode affects bridging as well as routing. If you have STP
enabled on the system and you have redundant bridged paths between
systems with different VLANs, STP blocks one of the paths unless you
enable Ignore STP mode. See Figure 28 later in this chapter for an
example of redundant paths between systems that have different
port-based VLANs.
bridge port stpState
on the