Content

| Summary

Concepts covered in this chapter include:

- VLANs solve many of the issues found in Layer 2 environments. These issues include broadcast control, isolation of problem components in the network, security, and load balancing through the use of a Layer 3 protocol between VLANs.
- VLAN identification allows different VLANs to be carried on the same physical link, called a trunk link. Four major trunking technologies exist: ISL, IEEE 802.1Q, IEEE 802.10, and ATM LANE. ISL encapsulates Ethernet frames, and IEEE 802.1Q embeds a tag in the Ethernet header.
- The VLAN Trunking Protocol (VTP) provides support for dynamic reporting of the addition, deletion, and renaming of VLANs across the switch fabric.
- VTP pruning permits the dynamic pruning of unnecessary VLAN traffic within the management domain.