CCNA 3 Labs and Study Guide - BINARYBB.INFO – @jagalbraith

342 Switching Basics and Intermediate Routing CCNA 3 Labs and Study Guide
Study Guide
VLAN Concepts
As a network engineer, it is important that you understand the logical function of a VLAN and how
VLANs can improve network performance. The completion exercise in this brief section provides a quick
review of VLAN concepts.
Vocabulary Exercise: Completion
Directions: Complete the paragraphs that follow by filling in appropriate words and phrases.
Up to this point in your studies, you have learned that a LAN includes all devices in the same broadcast
domain and that a switch is used to microsegment the collision domain. In this chapter, you learned that
switches can be configured with virtual LANs, or VLANs, to segment the broadcast domain at Layer 2.
Without VLANs, a switch treats all interfaces on the switch as being in the same broadcast domain.
A VLAN is a broadcast domain created by one or more switches. Configuration is as simple as putting
some interfaces in one VLAN and other interfaces in another VLAN.
List a few reasons or benefits for using VLANs:
■ Limit the size of broadcast domains
■ Group users by function, department, or some other logic instead of by physical location
■ Increase security by separating logically devices on the same LAN
■ Separate specialized traffic from user traffic (e.g. IP phones)
Layer 2 switches cannot forward traffic between VLANs. In fact, the switch maintains a separate MAC
address table for each VLAN so that broadcasts are contained within each VLAN. To communicate
between users on different VLANs, the traffic must pass through a router or Layer 3 switch. This can be
done by using a different Ethernet interface for each VLAN. Note that each VLAN would be on a different
subnet. It is more common to use one Fast Ethernet interface to trunk multiple VLANs and configure logical
subinterfaces.
Two basic VLAN configuration methods are available to the network engineer: static configuration, which
is port based, and dynamic configuration, which uses a VLAN Management Policy Server (VMPS). Static
VLAN configuration is by far the most widely implemented of these two methods. Dynamic VLAN configuration
is not currently a CCNA objective.
VLAN Configuration
Currently, the Cisco IOS is in a transition phase from configuring VLANs in VLAN database configuration
mode to configuring VLANs in global configuration mode. Because both ways are currently supported,
you need to be familiar with each. The configuration exercise in this section will walk you through
both methods for creating, modifying, applying, and deleting VLANs.
Learn VLAN Configuration Commands Exercise
True or False: You can assign a VLAN to an interface without creating the VLAN first. If true, what confirmation
message does the switch display? If false, what error message does the switch display?