Designing Scalable Networks

Table of Contents

Table of Contents

Introduction - A Small- to Medium-Sized Business Solutions Framework

Section Objectives

Upon completion of this introduction, you will be able to describe a framework you can use to simplify the complexities associated with analyzing customer network problems and creating Cisco scalable solutions.

Time Required to Complete This Section

Approximately 30 minutes

Media/Resources Required to Complete This Section

This section consists of one short reading assignment. You will need the following resources:

Reading Assignment

Role of the Cisco Certified Design Associate

Your role as a Cisco Certified Design Associate is to be a network design consultant. You will act like an architect, building comprehensive designs that solve your customer's internetworking problems and provide the required functionality, performance, and scalability. In the same way that an architect designs a building or house for a client, you will develop blueprints for an overall internetwork design, as well as components plans for various pieces of the internetwork.

CiscoFusion

Cisco has developed an integrated network architecture, called CiscoFusion. With the CiscoFusion architecture, multiple networking technologies, operating at different networking layers, can provide the right capabilities to handle different networking issues.

Many of your customers may already be aware of the recent internetworking trend toward an integrated view of networking technologies. As a Cisco Certified Design Associate, you will be uniquely positioned to produce network designs, based on CiscoFusion, that meet the needs of state-of-the-art networks that integrate Layer 2, Layer 3, and ATM services. For example, the intelligent networking services associated with Layer 3 can be combined with the cost-effective, high-capacity services provided by Layer 2 in both LANs and WANs.

Evolution of Layer 2 and Layer 3 Services

Layer 2, also known as the data link layer, operates within a specific LAN or WAN segment. In the last two years, LANs have been revolutionized by the exploding use of switching at Layer 2. Companies are replacing hubs with switches at a quick pace. LAN switches provide performance enhancements for new and existing data networking applications by increasing bandwidth and throughput for workgroups and local servers.

Layer 3, also known as the network layer, operates between and across segments. Protocols such as Internet Protocol (IP), Internetwork Packet Exchange (IPX), and AppleTalk's Datagram Delivery Protocol (DDP) operate at Layer 3. In the wide area, Layer 3 networking allows businesses to build global data networks. As an example, the global Internet is based on Layer 3 technology.

Layer 3 networking, implemented with routing, interconnects the switched workgroups and provides services such as security, quality-of-service (QoS) options, and traffic management. Routing provides the control needed to build functional, scalable networks.

Traditionally, Layer 2 switching has been provided by LAN switches, and Layer 3 networking has been provided by routers. Increasingly, these two networking functions are integrated into common platforms. There will still be a wide range of platforms providing different performance and capacity ranges for each networking function, but users will gain fundamental benefits from integration of the layers. Users will be able to reduce the number of networking devices that need to be purchased, installed, supported, and serviced. In addition, users will be able to efficiently apply Layer 3 services, such as security and QoS capabilities, to specific individual users and applications.

Mirroring the integration of Layer 3 networking technology into LAN switching devices, WAN switching equipment likely will increasingly incorporate Layer 3 networking capabilities. As traditional Layer 3 routers gain support for higher capacity and bandwidth, the integration of Layer 2 technologies will enable routers to achieve optimum levels of performance, port density, and cost effectiveness.

The following diagram shows how Layer 2 and Layer 3 switching can be used to facilitate communications between Client X and Server Y, with or without routing.
 
 

When Do You Use Layer 2 or Layer 3 Functionality?

The decision to use Layer 2 or Layer 3 functionality in a network design depends on what problems you are trying to solve for your customer. These problems can be any of the following:

A Small- to Medium-Sized Business Solutions Framework

To help reduce the complexity associated with identifying and analyzing customer problems, and designing solutions, Cisco has developed a basic framework into which most customer problems fit. The small- to medium-sized business solutions framework is represented as a triangle, as shown as follows:

Use the following simple rules when designing solutions to customer problems:

Job Aids

Throughout this course, you will find job aids such as procedures, charts, and checklists. The job aids will help you design scalable solutions that maximize your customer's satisfaction. Review the job aids quickly, keeping an eye open for procedures, charts, and checklists that will help you do your work. The job aids:

Steps for Designing Scalable Networks

This course teaches you the steps for designing networks. Each module and section includes reading assignments, job aids, and exercises or case studies. After you review the following module descriptions, proceed with the course by clicking on the "Module 1 - Identify Customer Needs" link.  
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