IS310--Chater 6 Network Design

Traditional Network Design Pros and Cons

Traditional network design is an approach that carefully analyzes network needs and selects specialized hardware to minimize equipment costs, typically suited for stable, slowly changing environments, but often requiring more staff time to manage and maintain.

Pros

• Useful for static and slowly evolving networks

Cons

• Costly

• Time-consuming

• This approach may not be adequate today due to

  • Rapid changed in tech

  • Escalating network traffic demands

  • Decrease in hardware costs and increase in staff costs

Network Architecture Components

1. Local Area Network

   1. Enables users to access the network (access layer)

2. Building backbone network (or distribution layer)

   1. Distributes network traffic to and from the LANs (carriers more traffic than the LAN)

3. Campus backbone (or core layer)

   1. Usually faster than the backbones inside buildings, carriers more traffic

4. Data center

   1. Contains orgs servers

5. Enterprise edge

   1. Wide Area Network (WAN)

   2. Internet access

   3. e-commerce edge

      1. Specialized LAN with a group of servers that enables data exchange with orgs and external entities

Building Block Network Design

Uses a few standard components to simplify design and reduce costs

Iterative design phases

• Needs analysis

  • Understand current and future network needs (users and apps)

• Technology Design

  • Examine available technologies to determine which meet or exceed needs

  • If needs are difficult to estimate, build higher capacity

• Cost Assessment

  • Evaluate the financial costs of technology

Needs Analysis

Goal: Understand (1) the geographic scope of the network and (2) the users and applications that will use it

Baselines

• create metrics of current operations to compare design requirements against

Deliverable: One or more logical network design

• showing the applications, circuits, clients, and servers

• Each is categorized as either typical or high traffic

• Not consider the physical elements

Needs Analysis Steps

1. Break down the network into architectural components

   1. Evaluate all seven components - define geographic scope

2. Review the existing and expected applications that will use the network

   1. Identify hardware and software requirements for these applications

   2. Identify protocols used by applications

3. Identify and assess network users

   1. Some users may have very different needs

   2. How many of each type of user?

4. Categorize network requirements

   1. Mandatory

   2. Desireable

   3. Wish List

Technology Design

Design includes clients, servers, circuits, and networking devices (routers, gateways, access points, switches, etc)

Designing clients and servers

• Specify the clients devices needed in standard units

• Servers are similarly allocated based on application needs

Designing circuits and network devices

• Capacity planning

  • The estimation of circuit size and type required for each network architecture component

• Circuit Loading

  • An assessment of the future amount of data transferred across a circuit (currently or in the future)

• Can design for average circuit traffic or peak circuit traffic (highest data volume on link)

Deliverable: One or more physical network design

Technology Design circuit traffic

Estimating circuit traffic

• average traffic vs peak traffic

• designing for peak traffic is ideal

Precision may not be the major concern

• Obtaining precise estimates is difficult and expensice

• traffic typically increases more than anticipated

Should network designers plan for excess capacity?

Upgrading costs 50-8-% more than designing higher capacity time

Very few complaints about overcapacity

Most organizations intentionally overbuild

Turnpike effect

Occurs when traffic increases faster than forecasted

When network are efficient and fast, users will use them more frequently

Cost Assessment

Financial analysis of the various technology design alternatives

Complex process that requires the analysis of many factors

• Circuit costs (cabling and installation)

• Internetworking devices(switches and routers)

• Hardware costs (clients, servers, power supplies)

• Software costs (OS, app software, middleware)

• network management and maintenance

• WAN and Internet Circuits

Deliverables:

• Finalized RF sent to vendors

• Revised tech design with detailed specifications including products and cots

• Business case for network deisgn

Request for Proposal (RFP)

• Detailed specification of equipment, softwarem and services desired from vendors

• Typically used in large network purchases

• Allows the org to evaluate offerings from different vendors

• Multi-vendor proposals

  • May provide better performance

  • May be less $$

  • May be more difficult to manage