How are the Spanning-Tree port parameters auto-edge-port, admin-edge-port and bpdu-protection used?

MVP
MVP
Q:

How are the Spanning-Tree port parameters auto-edge-port, admin-edge-port and bpdu-protection used?



A:

In the following example, switch Rack2sw1 is connected to the ProLiant server on port L1. The port is configured for the Spanning-Tree options, and the elapsed time before going into the forwarding state is displayed.

The configuration and verification associated with the diagram follows:

 

The default configuration for a port is “auto-edge-port.” The port will wait for 3 seconds to determine if any BPDU are received, before going into the forwarding state.

Rack2sw2# show spanning-tree l1 detail | include Edge

  AdminEdgePort             : No

  Auto Edge Port            : Yes

 

Rack2sw2(config)# interface l1 enable

I 06/09/12 16:22:35 00435 ports: port L1 is Blocked by STP

I 06/09/12 16:22:38 00076 ports: port L1 is now on-line

Three seconds pass before becoming on-line.

 

With “auto-edge-port” disabled, the port will go through the standard Spanning-Tree states of Blocking, Listening, Learning and Forwarding.

Rack2sw2(config)# no spanning-tree l1 auto-edge-port

Rack2sw2(config)# show spanning-tree l1 detail | include Edge

  AdminEdgePort             : No

  Auto Edge Port            : No

 

Rack2sw2(config)# interface l1 enable

I 06/09/12 16:27:05 00435 ports: port L1 is Blocked by STP

I 06/09/12 16:27:25 00076 ports: port L1 is now on-line

Twenty seconds pass before becoming on-line.

 

With “admin-edge-port” enabled, the port will immediately go into the forwarding state.

Rack2sw2(config)# spanning-tree l1 admin-edge-port

Rack2sw2# show spanning-tree l1 detail  | include Edge

  AdminEdgePort             : Yes

  Auto Edge Port            : No

 

Rack2sw2(config)# interface l1 enable

I 06/09/12 16:32:13 00435 ports: port L1 is Blocked by STP

I 06/09/12 16:32:13 00076 ports: port L1 is now on-line

Immediately becomes on-line.

 

With “admin-edge-port” and “auto-edge-port” enabled, the port will immediately go into the forwarding state:

Rack2sw2(config)# spanning-tree l1 auto-edge-port

Rack2sw2(config)# show spanning-tree l1 detail | include Edge

  AdminEdgePort             : Yes

  Auto Edge Port            : Yes

 

Rack2sw2(config)# interface l1 enable

I 06/09/12 16:54:59 00435 ports: port L1 is Blocked by STP

I 06/09/12 16:54:59 00076 ports: port L1 is now on-line

Immediately becomes on-line.

 

NOTE: When using “admin-edge-port” it is recommend to also configure “bpdu-protection”. This option disables the port if an unauthorized switch is plugged into the port.

 

Rack2sw2(config)# spanning-tree l1 bpdu-protection

Rack2sw2(config)# show spanning-tree l1 detail | include Edge|Protection

  BPDU Protection           : Yes

  AdminEdgePort             : Yes

  Auto Edge Port            : Yes

 

The following is a sample log file output that occurs when BPDUs are received on a port configured for BPDU protection.

I 06/09/12 17:08:19 00840 stp: port L1 disabled - BPDU received on protected port.

I 06/09/12 17:08:19 00898 ports: BPDU protect(5) has disabled port L1

I 06/09/12 17:08:19 00077 ports: port L1 is now off-lin

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