Cisco CCNP BCMSN Exam Tutorial The Four Or Five STP Port States
Below is a MRR and PLR article in category Computers Technology -> subcategory Computer Certification.
Cisco CCNP / BCMSN Exam Guide: Understanding STP Port States
Summary:
Explore the key STP port states crucial for the BSCI exam. Unpack these details with insights from Chris Bryant, CCIE12933.
Understanding STP Port States
As a CCNP candidate or CCNA, you might think you’ve covered all the details of the Spanning Tree Protocol (STP) during your initial studies. However, refreshing your knowledge is essential, especially for a switching exam. Many people consider there to be four STP port states, but officially, there’s a fifth.
The STP Port States:
1. Disabled State:
- Often overlooked, the disabled state is an official STP port state.
- A port in this state is administratively shut down.
2. Blocking State:
- Upon activation, a port enters the blocking state.
- In this phase, the port neither forwards nor receives frames and doesn’t learn MAC addresses.
- Its main function is to accept BPDUs from neighboring switches.
3. Listening State:
- After blocking, a port transitions to the listening state.
- It listens for and can now send BPDUs, but still doesn’t handle data frames.
4. Learning State:
- Next is the learning state, where the port prepares to handle frames by learning MAC addresses to build its MAC address table.
5. Forwarding State:
- Finally, the port reaches the forwarding state.
- It can now forward and receive data frames, exchange BPDUs, and update the MAC address table.
How to Monitor STP States
Monitor these states using the `show spanning-tree interface` command:
```plaintext
SW1
show spanning-tree interface fast 0/11
Vlan Role Sts Cost Prio.Nbr Type
--------- ---- --- ---- -------- ----
VLAN0001 Desg FWD 19 128.11 P2p
```
Practical Application
To see these states in action, practice by shutting down a port in your CCNA/CCNP lab and repeatedly execute the `show spanning-tree interface` command. Observing this on real Cisco equipment will enhance your understanding and prepare you for BCMSN exam questions. Remember, never practice commands on a live production network!
You can find the original non-AI version of this article here: Cisco CCNP BCMSN Exam Tutorial The Four Or Five STP Port States.
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