Cisco 350XG series Administration Manual page 277

Spanning Tree
STP Interface Settings
Cisco 350XG & 550XG Series 10G Stackable Managed Switches
It is recommended to set the value to Auto so that the device sets the
NOTE
port to fast link mode if a host is connected to it, or sets it as a regular STP
port if connected to another device. This helps avoid loops.
Edge Port is not operational in MSTP mode.
• Root Guard—Enables or disables Root Guard on the device. 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 you 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 BPDU
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 device. BPDUs are used to transmit spanning tree
information.
- Use Global Settings—Select to use the settings defined in the
Status and Global Settings
- Filtering—Filters BPDU packets when Spanning Tree is disabled on an
interface.
- Flooding—Floods BPDU packets when Spanning Tree is disabled on an
interface.
• Port Role—Displays the port or LAG role, per port or LAG per instance,
assigned by the MSTP algorithm to provide STP paths:
- Root—Forwarding packets through this interface provides the lowest
cost path for forwarding packets to the root device.
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STP
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