Chapter 6. VLANs and Trunks

This chapter covers the following topics that you need to master for the CCNP BCMSN exam:

• Virtual LANs This section reviews VLANs, VLAN membership, and VLAN configuration on a Catalyst switch.

• VLAN Trunks This section covers transporting multiple VLANs over single links and VLAN trunking with Ethernet.

• VLAN Trunk Configuration This section outlines the Catalyst switch commands that configure VLAN trunks.

• Troubleshooting VLANs and Trunks This section provides commands to use when a VLAN or trunk is not operating properly.

Switched campus networks can be broken up into distinct broadcast domains or virtual LANs (VLAN). A flat network topology, or a network with a single broadcast domain, can be simple to implement and manage. However, flat network topology is not scalable. Instead, the campus can be divided into segments using VLANs, while Layer 3 routing protocols manage interVLAN communication.

This chapter details the process of defining common workgroups within a group of switches. It covers switch configuration for VLANs, along with the method of identifying and transporting VLANs on various types of links.