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Defining VLANs

Implementing Best Practices for VLANTopologies

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Issues in a Poorly Designed Network

Unbounded failuredomains

Large broadcast domains

Large amount of

unknown MAC unicasttraffic

Unbounded multicasttraffic

Management and

support challenges

Possible securityvulnerabilities

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Scalable Network Addressing

Allocate IP address spaces in contiguous blocks.

Allocate one IP subnet per VLAN.

IT, Human Resources Sales, Marketing Finance, Accounting

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Interconnection Technologies

Technology Use

Fast Ethernet Connects end-userdevices to the access

layer switchGigabitEthernet

Access to distributionswitch, high-use servers

10-GigabitEthernet

High-speed switch toswitch links, backbones

EtherChannel High-speed switch toswitch links, backboneswith redundancy

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Determining Equipment and Cabling Needs

Each link providesadequate bandwidth fortraffic aggregatingover

that link.

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VLANs and the Logical Network

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Network Traffic Types

Traffic types to consider:

Network management

IP telephony

Multicast

Normal data

Scavenger class

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Traffic Path for IP Telephony

Consider complete traffic path when placing equipment andconfiguring VLANs.

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Traffic Path for IP Multicast

Consider complete traffic path when placing equipment andconfiguring VLANs.

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Summary

Poorly designed networks can lead to large broadcastdomains.

A hierarchical IP addressing scheme scales well in the CampusInfrastructure module.

The interconnection technology used depends on the amountof traffic the link must carry.

Select the best equipment, cabling, and interconnectiontechnologies to connect devices.

VLANs should map to the IP hierarchy for the Campus

Infrastructure module. Separate voice and data VLANs are recommended.

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