Configuring the Spanning Tree

STP is the abbreviation for spanning tree protocol, and RSTP is the abbreviation for rapid spanning tree protocol. Generally, the topology for the Layer 2 switching network involves the loop. This may result in the broadcast storm and MAC bridge table flapping. The STP or RSTP protocol is used to trim a bridge LAN into a single spanning tree based on a logic topology to prevent the broadcast storm that results from the looped Ethernet services.

Prerequisites

VB must be created.

EPLAN services must be created.

It applies to the 11LEX4, 11LEM24, L4G and TBE board.

Context

STP applies to a redundant network. Based on a certain algorithm, the STP is used to block redundant trails so that a loop network can be trimmed as a tree network. In this way, the proliferation and endless cycling of packets in the loop network are avoided. Besides, a connected network without redundant trails can be formed in the case of the link failure.

RSTP is an improvement of the STP. The RSTP not only supports all the functions of the STP, but also shortens the delay of generating the network topology structure and ensures the connectivity of the network.

STP is based on this basic principle. That is, bridge protocol data units (BPDUs) are transmitted between bridges to decide the network topology structure. The STP blocks redundant links to prevent possible loops in the bridged network, and activates the redundant backup links to restore the network connectivity when the working trail fails.

Procedure

Configure the spanning tree. That is, rapidly set the parameters for configuring the spanning tree.
1. Select the desired Ethernet board on the NE Explorer, and choose Configuration > Layer-2 Switching Management > Spanning Tree from the Function Tree.
2. Click the Protocol Enable tab, and select a service. Click Rapid Configuration. In the Rapid Configuration dialog box displayed, set the relevant parameters.
  
  NOTE:
  Protocol Enable: Disabled, Enabled. Default value: Disabled.
  
  Protocol Type: RSTP, STP. Default value: RSTP.
  
  Bridge Priority: 0 to 65535. Step length: 4096.
  
  Port Priority: 0 to 255. Default value: 128.
3. Click Finish.
4. Optional: Click Protocol Reset to restart the STP or RSTP protocol. All the parameters of the spanning tree are restored to the default values.
Set and query bridge parameters.
1. Click the Bridge Parameter tab, and select the corresponding service. Double-click fields such as Priority and Max Age (s) to set the parameters.
  
  NOTE:
  Priority: refers to the bridge priority. Value range: 0-65535. Step length: 4096.
  
  MAC Address: used to query the bridge MAC address.
  
  Max Age (s): refers to the maximum lifecycle of a message. Value range: 6-40. Input condition: 2×(Hello Time+1)≤Max Age≤2×(Forward Delay-1).
  
  Hello Time (s): refers to the sending period of BPDU configuration information. Value range: 1-10. Default value: 2.
  
  Forward Delay (s): used to set the forward delay of a configured port. Value range: 4-30. Default value: 15.
  
  TxHoldCount (Times/s): refers to the number of BPDUs that can be sent per second. Value range: 1-10. Default value: 6.
Set and query port parameters.
1. Click the Port Parameter tab, and select the corresponding service. Double-click fields such as Priority and Admin Edge Attribute to set the parameters.
  NOTE:
  Priority: used to set the port priority. Value range: 0-240. Step length: 16.
  
  Port Path Cost: used to set the port path overhead value for calculating the network topology. Value range: 1-200000000.
  Status: used to query the port status. In the case of RSTP, the port status includes Discarding, Forwarding, Learning, and Disable. In the case of STP, the port status includes Blocking, Listening, Learning, Forwarding, Discarding, and Disable.
  Blocking: The port in the blocking status is involved in the topology. It does not learn MAC addresses.
  Listening: The port in the listening status is involved in the topology. It can discard service packets. It does not, however, learn the MAC addresses. The listening status is a temporary status when a topology is being created or transformed.
  Learning: The port in the learning status is involved in the topology. It can discard service packets. In addition, it learns the MAC addresses of the service packets to prepare for forwarding the packets. The learning status is a temporary status when a topology is being created or transformed.
  Forwarding: The port in the forwarding status is involved in the topology. It can forward service packets. Only the root port and the designated port have this status.
  Discarding: The port in the discarding status is involved in the topology. It does not learn the MAC addresses. It can, however, discard service packets.
  Disable: The port in the disable status is not involved in the topology. It does not start the protocol.
  Admin Edge Attribute: Enabled, Disabled.
  
  Protocol Enabled: Enabled, Disabled.
  
  Auto Edge Detection: Enabled, Disabled. This parameter is used to set the enabling state of auto edge detection.
2. Optional: When you change the spanning tree type from STP to RSTP, click Protocol Transfer to force the port to immediately send RSTP packets. In this way, the spanning tree type is changed.
  NOTE:
  After the port protocol type is changed from STP to RSTP, the port does not immediately send RSTP packets unless it receives an RSTP packet. At this point, you can click Protocol Transfer to force the port to immediately send RSTP packets.
Query bridge running information.
1. Select the Bridge Running Info tab, and click Query to view the bridge running information in the interface displayed.
Query port running information.
1. Select the Port Running Info tab, and click Query to view the port running information in the interface displayed.
Set the point-to-point attribute.
1. Click the Point to Point Attribute tab, and select the corresponding port. Double-click the Point-to-Point Attribute field to set the Point-to-Point Attribute parameter.
  NOTE:
  Point-to-Point Attribute: Adaptive connection, Shared media, Link connection
  Adaptive connection: If the port is a full-duplex or VCTRUNK port and the port has the point-to-point attribute, the port state can be transited rapidly.
  Shared media: If the port has the non-point-to-point attribute, the port state cannot be transited rapidly.
  Link connection: If the port has the point-to-point attribute, the port state can be transited rapidly.