As a candidate for CCNP and CCNA, you might be tempted to skip or just browse the many details of Spanning Tree Protocol. After all, you learn all that in your CCNA studies, right? That's right, but it never hurts to review STP for switching exam! In addition, many of us think of the four STP port states - but officially, there is a fifth!
The disabled are not generally regarded as the port states of STP, but Cisco does not officially state that this is one of STP. Port is a defect that is administratively closed.
Once the door is open, the door will go into a locked state. As the name suggests, the door can not do much in this country - not forwarding frames, no frames received, and then there is no learning of MAC addresses. The only thing you can do this port is receiving BPDUs from neighboring switches.
A door then go from blocking mode to listen. The obvious question is "listen to what?" Listening for BPDUs - and this port can now send BPDUs as well. I still can not send or receive data frames.
When the port is running in the listening mode of learning mode, which is preparing to send and receive frames. In the learning mode, the door began to learn the MAC address in preparation for adding them to the table of MAC addresses.
Finally, the door may enter into forward mode. This allows the port to transmit and receive data frames, send and receive BPDUs, and place the MAC address in its MAC table.
To see the STP mode interface that is provided, use the show interfaces command include trees.
SW1 # show spanning-tree interface fast 0 / 11
VLAN Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- ----------
Desg VLAN0001 FWD 19 128.11 P2P
To see action in these countries, shut the door in / CCNA CCNP lab of your home and continue to run the show covers the interface. When you see this in action on real Cisco equipment, will not be a problem with BCMSN exam questions. Just do not practice this or other Cisco command on your production network!
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