David-Wairimu-Cybersecurity-Portfolio/Day Nine Reflection – VLAN Trunks and Dynamic Trunking Protocol (DTP) at main · davidwairimu-netsec/David-Wairimu-Cybersecurity-Portfolio · GitHub

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On day nine, I learnt about VLAN trunks and the Dynamic Trunking Protocol (DTP). The lesson focused on how switches communicate VLAN information across networks, how trunk links are configured, and how switches automatically negotiate trunk connections.

Topics Covered and What I Learnt
3.4 VLAN Trunks
1. Introduction to VLAN Trunks

I learnt that VLAN trunks are special links between switches that carry traffic from multiple VLANs through a single physical connection. I understood that:

Trunks allow VLAN communication across switches
Multiple VLANs can travel through one link
Trunking improves scalability and network efficiency

This topic helped me understand how large switched networks maintain VLAN communication.

2. Trunk Configuration Commands

I learnt the commands used to configure trunk ports on switches. During the lesson, I practised:

Setting ports as trunk ports
Specifying encapsulation methods
Assigning native VLANs
Allowing specific VLANs on a trunk

This improved my understanding of switch configuration and VLAN management.

3. Trunk Configuration Example

I studied practical examples showing how VLAN trunks are configured between switches. I observed:

How switches exchange VLAN traffic
How trunk links are established
How devices in the same VLAN communicate across multiple switches

This helped me connect theory with real network implementation.

4. Verify Trunk Configuration

I learnt how to verify whether trunk links were working properly using verification commands. I checked:

Active trunk ports
Allowed VLANs
Native VLAN settings
Trunk operational status

This strengthened my troubleshooting and verification skills.

5. Reset the Trunk to the Default State

I learnt how to remove trunk configurations and restore switch ports to their default settings. I understood the importance of:

Clearing incorrect configurations
Returning ports to access mode
Troubleshooting misconfigured trunks

This helped me understand configuration management and recovery procedures.

6. Packet Tracer – Configure Trunks

I completed a Packet Tracer activity where I configured VLAN trunks between switches. During the lab, I:

Configured trunk ports
Allowed VLAN traffic across switches
Verified trunk communication
Tested VLAN connectivity

The practical exercise improved my confidence in VLAN trunk configuration.

7. Lab – Configure VLANs and Trunking

Finally, I completed a lab involving both VLAN creation and trunk configuration. The lab helped me:

Create and assign VLANs
Configure trunk links
Verify VLAN communication
Troubleshoot connectivity issues

This gave me hands-on experience in managing VLAN environments.

3.5 Dynamic Trunking Protocol (DTP)
8. Introduction to DTP

I learnt about Dynamic Trunking Protocol (DTP), a Cisco protocol that allows switches to automatically negotiate trunk links. I understood that:

DTP simplifies trunk configuration
Switches can dynamically form trunk connections
Proper configuration is important for security and stability

This topic introduced me to automated trunk negotiation.

9. Negotiated Interface Modes

I learnt the different DTP interface modes used by switches, including:

Dynamic desirable
Dynamic auto
Trunk mode
Access mode

I understood how these modes affect whether a trunk link is established between switches.

10. Results of a DTP Configuration

I studied how different DTP configurations interact with one another. I observed:

Which interface mode combinations create trunks
Which combinations remain as access ports
How incorrect settings can prevent trunk formation

This improved my understanding of switch-to-switch communication.

11. Verify DTP Mode

I learnt how to verify DTP configurations using switch commands. I practised checking:

Current interface modes
Trunk negotiation status
Operational trunk settings

This strengthened my ability to troubleshoot trunk negotiation issues.

12. Packet Tracer – Configure DTP

I completed a Packet Tracer activity where I configured and tested DTP between switches. During the exercise, I:

Configured interface negotiation modes
Observed automatic trunk formation
Verified successful trunk communication

This practical activity helped me understand how DTP operates in real network environments.

13. Check Your Understanding – Dynamic Trunking Protocol

Finally, I completed an assessment activity to test my understanding of DTP concepts. The exercise helped me:

Differentiate DTP modes
Understand trunk negotiation behavior
Analyse switch communication and trunk formation

This strengthened my knowledge of VLAN trunking and automated switch configuration in enterprise networks.