Table 233: Spanning Tree MST Port Configuration Fields (continued)
Field
Description
Port Role
The role of the port within the MST, which is one of the following:
•
Root – A port on the non-root bridge that has the least-cost path to the
.
•
Designated – A port that has the least-cost path to the root bridge on its
segment.
•
Alternate – A blocked port that has an alternate path to the root bridge.
•
Backup – A blocked port that has a redundant path to the same network
segment as another port on the bridge.
•
Master – The port on a bridge within an MST instance that links the MST
instance to other
regions.
•
Disabled – The port is administratively disabled and is not part of the
spanning tree.
Port Forwarding State
•
Blocking – The port discards user traffic and receives, but does not send,
BPDU (Bridge Protocol Data Unit)
s. During the election process, all ports are
in the blocking state. The port is blocked to prevent network loops.
•
Listening – The port sends and receives BPDUs and evaluates information to
provide a loop-free topology. This state occurs during network convergence
and is the first state in transitioning to the forwarding state.
•
Learning – The port learns the MAC addresses of frames it receives and
begins to populate the MAC address table. This state occurs during network
convergence and is the second state in transitioning to the forwarding state.
•
Forwarding – The port sends and receives user traffic.
•
Disabled – The port is administratively disabled and is not part of the
spanning tree.
Port Priority
The priority for the port within the
. This value is used in determining which
port on a switch becomes the root port when two ports have the same least-cost
path to the root. The port with the lower priority value becomes the root port. If
the priority values are the same, the port with the lower interface index becomes
the root port.
Port Path Cost
The path cost from the port to the root bridge.
Description
A user-configured description of the port.
After you select an interface and click
Edit
, a window opens and allows you to
edit the MST port settings and view additional MST information for the interface.
The following information describes the additional fields available in this window.
Auto-calculate Port Path Cost
Shows whether the path cost from the port to the root bridge is automatically
determined by the speed of the interface (Enabled) or configured manually
(Disabled).
Port ID
A unique value that is automatically generated based on the port priority value
and the interface index.
Port Up Time Since Counters
Last Cleared
The amount of time that the port has been up since the counters were cleared.
Port Mode
The administrative mode of spanning tree on the port.
Designated Root
The bridge ID of the root bridge for the MST instance.
Designated Cost
The path cost offered to the LAN by the designated port.
Designated Bridge
The bridge ID of the bridge with the designated port.
Configuring Switching Information
ExtremeSwitching 200 Series: Administration Guide
231
