Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Semester 3, v. 2.1.2

Chapter 3: Virtual LANs

Curriculum ReviewCurriculum Review

Youngstown State University Youngstown State University Cisco Regional AcademyCisco Regional Academy

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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DisclaimerDisclaimer

This presentation is intended for review purposes by Cisco Networking Academy Program teachers and students only.This presentation is not a substitute for careful study of the Cisco Academy curriculum.Most of the text and graphics have been copied directly from the on-line curriculum, and remain the copyrighted property of Cisco Systems.CCNA 640-507 objectives are used for all YSU Regional authored reviews.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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ContentsContents

Part 1: VLANsPart 2: Segmenting with SwitchesPart 3: VLAN ImplementationPart 4:Benefits of VLANs

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Chapter Learning ObjectivesChapter Learning Objectives

You will be able to:– Define the role of a switch in creating VLANs.– Describe frame filtering and frame tagging.– Describe beneficial reasons for implementing

VLANs.– Explain port centric, static, and dynamic

VLANs.– Explain how VLANs control broadcasts.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Part 1Part 1

Virtual LANsVirtual LANs

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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VLAN: OverviewVLAN: Overview

Traditional LANs are:– Configured according to Layer 1

requirements.– Grouped by their location

relative to the hub and cable runs to the IDF/MDF.

– Not segmented by workgroup association or need for bandwidth.

– The “structure” is controlled by the physical layout, not the logical needs.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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VLANs: OverviewVLANs: Overview

A VLAN is a logical grouping of devices or users that can be grouped by: – function, – department, – or application,

Regardless of their physical segment location.

Logical requirements rule over the physical layout.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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VLANs: OverviewVLANs: Overview

A group of ports or users in the same broadcast domain.

Can be selected according to:– Port ID number– MAC address– Protocol– Application

Use switches and proprietary software.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Part 2Part 2

Segmenting with SwitchesSegmenting with Switches

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Removing the Physical BoundaryRemoving the Physical Boundary

Using VLANs, you can group switch ports and their users into logically defined workgroups, such as:– Coworkers in the

same department.– A cross-functional

product team.– User groups sharing the

same application.

Single or multiple switches can be used.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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VLAN’s Across the BackboneVLAN’s Across the Backbone

To eliminate the physical restriction:– VLAN information between interconnected switches

and routers, must be carried and reside on the corporate backbone.

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Routers in the VLANRouters in the VLAN

Still provide:– Broadcast control– Route processing– Subnet connectivity

But now also:– Connect the VLANs

that are “logically” created but are not on the same “physical” location!

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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VLAN FramesVLAN Frames

Switches make filtering and forwarding decisions by frame, using VLAN metrics.– Frame filtering– Frame tagging

A frame is compared to the metrics and then is:– sent,– filtered, – or broadcast.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Frame FilteringFrame Filtering

Each switch develops a filtering table. Each frame can be filtered according to:

– MAC address, or– Layer 3 protocol type

• IP• IPX, etc.

Like routers, switches share address table data across the backbone.

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Frame TaggingFrame Tagging

Places a unique ID in the header of each frame as it is moves through the network backbone.– ID is understood and examined by each switch prior

to any broadcasts or transmissions to other switches, routers, or hosts.

– Functions at Layer 2; low administration!– Selected by IEEE as

VLAN standard.• IEEE 802.1q

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Part 3Part 3

VLAN ImplementationVLAN Implementation

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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VLAN Ports and BroadcastsVLAN Ports and Broadcasts

Each switch port can be assigned to a VLAN.– Only ports assigned to the same VLAN share

broadcasts.– Switched VLANs can therefore segment broadcast

domains like routers.

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Types of VLANsTypes of VLANs

Three types of VLAN implementation– Port-centric– Static– Dynamic

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Port CentricPort Centric

All nodes connected to ports in the same VLAN are assigned the same VLAN ID. – Users are assigned by port. – Easy administration. – Increased security

between VLANs. – Packets do not

"leak" into other domains.

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Static VLANsStatic VLANs

Switch ports are assigned to a VLAN.– Any host that plugs into a port is automatically

a member of that port’s VLAN gorup.

Easy to configure and monitor.

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Dynamic VLAN’sDynamic VLAN’s

Central database server maintains the VLAN assignments.– When a new host is connected to an open port, the

switch checks the database for VLAN assignment. – Assignment

based on:• MAC• Logical address• Protocol type.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Part 4Part 4

Benefits of VLANsBenefits of VLANs

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Moving HostsMoving Hosts

Physical moves are one of network managers biggest headache.– Moves and additions require the least amount of

reconfiguration when using VLANs.– Hosts can move without

changing IP or subnet membership as long as:

• They are connected to a VLAN switch.

• Retain their VLAN ID.

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VLANs Control BroadcastsVLANs Control Broadcasts

Switches not using VLANs, send broadcasts out every port just like a hub.

Broadcast traffic within one VLAN is not sent outside that VLAN.– The smaller the VLAN

membership, the less hosts have to deal with excess broadcast traffic.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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Improved SecurityImproved Security

A network manager can: – Restrict the number of users in a VLAN group – Prevent a user from joining the VLAN without first

receiving approval.

Used with router ACL’s for tight control.

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Save Money!Save Money!

Use existing hubs to connect many VLAN members to the same VLAN switch port.

Relocating a host to a new VLAN can be as easy as plugging into a different hub.

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SummarySummary

Switched VLANs are a secure, layer 2, cost effective way to group users regardless of physical location.

VLAN membership ID can travel the backbone. Common ID groupings are filtering, frame

tagging, and frame identification. VLAN’s provide

– Broadcast Control– Workgroup security– Cost effective additions or moving of hosts.

Robert E. Meyers CCNA, CCAIYoungstown State UniversityCisco Regional Academy Instructor

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End