© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 1 Version 4.0 VLANs LAN Switching and...

© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 1Version 4.0

VLANs

LAN Switching and Wireless – Chapter 3

© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 2

Objectives Explain the role of VLANs in a converged network.

Explain the role of trunking VLANs in a converged network.

Configure VLANs on the switches in a converged network topology.

Troubleshoot the common software or hardware misconfigurations associated with VLANs on switches in a converged network topology.


It would be great to group the people with the resources they use regardless of their geographic location, and it would make it easier to manage their specific security and bandwidth needs.


When you configure a VLAN, you can name it to describe the primary role of the users for that VLAN. As another example, all of the student computers in a school can be configured in the "Student" VLAN. Using VLANs, you can logically segment switched networks based on functions, departments, or project teams.

These VLANs allow the network administrator to implement access and security policies to particular groups of users.

A VLAN is a logically separate IP subnetwork.

You do not need VLANs to have multiple networks and subnets on a switched network, but there are definite advantages to using VLANs.


Security - Groups that have sensitive data are separated from the rest of the network.

Cost reduction - Cost savings result from less need for expensive network upgrades and more efficient use of existing bandwidth and uplinks.

Higher performance - Dividing flat Layer 2 networks into multiple logical workgroups (broadcast domains) reduces unnecessary traffic on the network and boosts performance.

Broadcast storm mitigation - Dividing a network into VLANs reduces the number of devices that may participate in a broadcast storm.

Improved IT staff efficiency - VLANs make it easier to manage the network because users with similar network requirements share the same VLAN. When you provision a new switch, all the policies and procedures already


‘Normal’ VLAN ID’s 1- 1005

1002 fddi-default active 6

1003 token-ring-default active 9

1004 fddinet-default active 7

1005 trnet-default active 8 (trunk)

One Cisco Catalyst 2960 switch can support up to 255 normal range and extended range VLANs, although the number configured affects the performance of the switch hardware.


A port-based VLAN is associated with a port called an access VLAN.

However in the network there are a number of terms for VLANs. Some terms define the type of network traffic they carry and others define a specific function a VLAN performs. 3.1.2.1


The default VLAN for Cisco switches is VLAN 1. VLAN 1 has all the features of any VLAN, except that you cannot rename it and you can not delete it. By default, Layer 2 control traffic, such as CDP and spanning tree protocol traffic, are associated with VLAN 1. In the figure, VLAN 1 traffic is forwarded over the VLAN trunks connecting the S1, S2, and S3 switches. It is a security best practice to change the default VLAN to a VLAN other than VLAN 1;


DATA

DEFAULT

NATIVE (don’t even ask)

MANAGEMENT


VLAN types

3.1.2.2 introduces VOIP as a good example of segregating application traffic into separate VLAN’s

VOIP is a good example, but its introduction in these notes leads to quite complex narrative in these notes.

Normal and IP telephony ‘trunked’ over common lines. See 3.1.2.3


VLAN port membership modes

Static, dynamic and Voice 3.1.3.1

We will be using static in lab’s


Manage broadcast domains with VLANs

3.1.4.1 (play simulation)

3.1.4.2 Try to follow the discussion on

Intra v. inter VLAN comm’s.


Layer 3 switching – this is new material. May not feature in either lab’s or exams. Will keep you advised.


Explain the Role of Trunking VLANs in a Converged Network Trunking when using multiple VLAN’s

Look up http://en.wikipedia.org/wiki/Trunking


Explain the Role of Trunking VLANs in a Converged Network Describe how a trunk works


Explain the Role of Trunking VLANs in a Converged Network Describe the switch port trunking modes


Configure VLANs on the Switches in a Converged Network Topology Describe the steps to configure trunks and VLANs


Configure VLANs on the Switches in a Converged Network Topology Describe the Cisco IOS commands used to create a

VLAN on a Cisco Catalyst switch


Configure VLANs on the Switches in a Converged Network Topology Describe the Cisco IOS commands used to manage

VLANs on a Cisco Catalyst switch


Configure VLANs on the Switches in a Converged Network Topology Describe the Cisco IOS commands used to create a

trunk on a Cisco Catalyst switch


Troubleshoot Common Software or Hardware Misconfigurations Associated with VLANs Describe the common problems with VLANs and trunks


Describe the common problems with VLANs and trunks

Troubleshoot Common Software or Hardware Misconfigurations Associated with VLANs


Describe how to use the troubleshooting procedure to fix a common problem with VLAN configurations

Troubleshoot Common Software or Hardware Misconfigurations Associated with VLANs


Summary VLANS

Allows an administrator to logically group devices that act as their own network

Are used to segment broadcast domains

Some benefits of VLANs include

Cost reduction, security, higher performance, better management


Summary

Types of Traffic on a VLAN includeData

Voice

Network protocol

Network management

Communication between different VLANs requires the use of

Routers


Summary

Trunks

A common conduit used by multiple VLANS for intra-VLAN communication

EEE 802.1Q

The standard trunking protocol

Uses frame tagging to identify the VLAN to which a frame belongs

Does not tag native VLAN traffic

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 1 Version 4.0 VLANs LAN Switching and...

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