Foundation Summary

The Foundation Summary is a collection of tables that provides a convenient review of many key concepts in this chapter. If you are already comfortable with the topics in this chapter, this summary could help you recall a few details. If you just read this chapter, this review should help solidify some key facts. If you are doing your final preparation before the exam, these tables and figures are a convenient way to review the day before the exam.

Table 6-2. VLAN Trunk Encapsulations

Encapsulation	Tagging Characteristics
ISL	Adds a 26-byte header and a 4-byte trailer to each frame, and includes a 15-bit VLAN ID
IEEE 802.1Q	Adds a 4-byte tag, includes a 12-bit VLAN ID

Table 6-3. VLAN and Trunking Configuration Commands

Task	Command Syntax
Create VLAN	vlan vlan-num name vlan-name
Assign port to VLAN	interface type module/number switchport mode access switchport access vlan vlan-num
Configure trunk	[View full width] interface type mod/port switchport trunk encapsulation {isl | dot1q| negotiate} switchport trunk native vlan vlan-id switchport trunk allowed vlan {vlan-list | all | {add | except | remove} vlan-list} switchport mode {trunk | dynamic {desirable | auto}}

Table 6-4. VLAN and Trunking Troubleshooting Commands

Task	Command Syntax
Verify VLAN configuration	show vlan id vlan-id
Verify active trunk parameters	show interface type mod/num trunk
Compare trunk configuration and active parameters	show interface type mod/num switchport
Verify DTP operation	show dtp [interface type mod/num]