Configuring the Spanning Tree Protocol
Defining Spanning Tree Interface Settings
Cisco 500 Series Stackable Managed Switch Administration Guide
239
14
•
Edge Port
—Enables or disables Fast Link on the port. If Fast Link mode is
enabled on a port, the port is automatically set to Forwarding state when
the port link is up. Fast Link optimizes the STP protocol convergence. The
options are:
-
Enable
—Enables Fast Link immediately.
-
Auto
—Enables Fast Link a few seconds after the interface becomes
active. This allows STP to resolve loops before enabling Fast Link.
-
Disable
—Disables Fast Link.
NOTE
It is recommended to set the value to auto so that the switch will
set the port to fast link mode if a host is connected to it, or set it as regular
STP port if connected to another switch. This helps avoid loops.
•
Root Guard
—Enables or disables Root Guard on the switch. The Root Guard
option provides a way to enforce the root bridge placement in the network.
Root Guard ensures that the port on which this feature is enabled is the
designated port. Normally, all root bridge ports are designated ports, unless
two or more ports of the root bridge are connected. If the bridge receives
superior BPDUs on a Root Guard-enabled port, Root Guard moves this port
to a root-inconsistent STP state. This root-inconsistent state is effectively
equal to a listening state. No traffic is forwarded across this port. In this way,
Root Guard enforces the position of the root bridge.
•
BPDU Guard
—Enables or disables the Bridge Protocol Data Unit (BPDU)
Guard feature on the port.
The BPDU Guard enables the user to enforce the STP domain borders and
keep the active topology predictable. The devices behind the ports that
have BPDU Guard enabled cannot influence the STP topology. At the
reception of BPDUs, the BPDU guard operation disables the port that has
Protest configured. In this case, a BPDU message is received, and an
appropriate SNMP trap is generated.
•
BPDU Handling
—Select how BPDU packets are managed when STP is
disabled on the port or the switch. BPDUs are used to transmit spanning tree
information.
-
Use Global Settings
—Select to use the settings defined in the
STP
Status and Global Settings
page.
-
Filtering
—Filters BPDU packets when Spanning Tree is disabled on an
interface.