Chapter 6: Network Design

All organizations have networks

True

Most network design projects are upgrades to existing networks

True

Network design isn’t challenging

False

What are the network architecture components?

1) LAN
2) Building backbone network
3) Campus backbone
4) Data center
5) Enterprise edge

• WAN

• Internet access

• e-commerce edge

The first network architecture componet is the _____

local area network(LAN)

What does the LAN do?

Enables users to access the network

What is the LAN referred to as?

Access layer

The second network architecture component is the ______

building backbone network

What does the building backbone network do?

Distributes netowrk traffic to and from the LANs

What do vendors call the building backbone layer?

Distribution layer

The third network architecture component is the _____

campus backbone

What does the campus backbone do?

Connects all the buildings on one campus

What is the campus backbone referred to as?

The core layer

The fourth network architecture component is the______

data center

What does the data center do?

Contains the organizations servers (like an LAN but designed/managed differently)

What three components of the network architecture make up the enterprise edge?

1) WAN

2) Internet Access

3) e-Commerce edge

What do the components of the enterprise edge do?

They connect the campus to the rest of the world

What does the WAN do as a network architecture component?

A private network that connects its different campus locations. Usually leased from common carriers such as AT&T.

What does the internet access do as a network architecture component?

Enables the organization to connect to the Internet

What does the e-commerce edge do as a network architecture component?

Is a special LAN that enables electronic data exchange between organization and its external entities that it does business with.

The traditional network design process follows a very structured design process similar to what?

The process used to build application systems.

What is the four step network design process

1) Network analyst meets with users to identify needs and the application systems planned for the network

2) Analyst makes a precise estimate of the amount of data each user will send/receive. This estimates a total amount of traffic on each part of the network

3) Circuits needed to support traffic plus increase in traffic are designed and we estimate cost

4) The network is built and implemented

The traditional network design process works well for what kind of network?

a static or slowly evolving network

Networking today is the traditional process

False

What are the three forces that make the traditional design process less appropriate for todays networks?

1) Tech of client/server computers, networking devices and circuits are changing rapidly

2) Higher network traffic

3) Balance of costs has changed

What is the newer and simpler network design approach?

The building-block process

How does the building-block process work?

The goal is simplicity. Using a few standard components over and over, even if they provide more capacity than needed.

What is the strategy of building-block process referred to as?

narrow and deep (more easily managed)

What are the three steps to the building-block network design process?

1) Needs analysis
2) Technology design
3) cost assessment

As the first step in the building-block network design process, what is needs analysis?

The designer tries to understand the current and future network needs of its users. Why is the network being built?

• baseline

• network components

• application systems

• Network users

• needs categorization

As the second step in the building-block network design process, what is technology design?

Examines available tech and decides which options meet users needs

• Clients and servers

• circuits

As the third step in the building-block network design process, what is cost assessment?

The relative costs of the technologies are considered

• off the shelf

• request for proposal

Explain the cyclical nature of building-block network design.

After steps 1-3 are complete the process cycles back through them again. All layers are refined by the previous to produce new assessment of users needs, changes in tech design and changes in cost assessment.

Needs Analysis: In many cases the network is being designed to improve or enable what?

Improve poor performance or enable new applications to be used

The goals in network design are slightly different between LANs/BNs and WANs

True

Much of the needs analysis today has already been done. Why?

Because we are mainly doing network upgrades rather than making new ones

What is a baseline and what is it used for?

In needs analysis, a baseline is an understanding of current operations. It provides an idea of current operations vs future operations

What are the primary objectives of needs analysis?

1) The geographic scope of the network

2) The users and applications that will use it

Overall, we need to produce a logical network design (not specifying tech/procuts used, but the network elements needed)

The first step in needs analysis is breaking the network into ____

Network architecture components (not all will be used)
(ex: LANs, building backbones, Campus backbones, WANs, Internet access, E-commerce edge, data centers)

What is baselining?

The designers reviewing the list of applications that will use the network and identifying the location of each

In baselining, what should you identify about the hardware and software?

The requirements of each application that will use the network and the protocol each of them has

What accounts for the majority of network traffic?

Internet use. It used to be application systems.

What must we understand about applications in regard to their users?

Assess the number and type of uses that the application generates/receives traffic from and identify their location on the network diagram.

Network requirements are organized into these three parts

1) Mandatory requirements
2) Desirable requirements
3) wish-list requirements

What is the key deliverable for the needs assessment stage

A set of logical network diagrams showing the applications, circuits, clients, and servers.

Technology design is often referred to as_____

physical network design

Typical uses are allocated the _______ client computers as are servers supporting typical applications. While users and servers for applications needing more powerful computers are assigned some ______

base-level; advanced computer

What are the two interrelated decisions in designing network circuits and devices?

1) The fundamental technology and protocols

2) The capacity of each circuit

What is capacity planning?

Estimating the size and type of the standard and advanced network circuits for each type of network

Designing circuit capacities for backbone networks is more _______ because backbones move traffic from many computers at one time. To analyze this we can focus either on the _____ circuit traffic or the ____ circuit traffic.

challenging; average; peak

Cost assessment is used to look at the relative cost of technologies used in a network design.

True

The step of understanding current traffic on a network provides a baseline against which future network requirements can be compared.

True

Cost assessment is the step in the network design in which many complex factors related to costs are documented.

True

Nowadays, most organizations use a simpler approach to network design called the ____ approach

building-block

Which of the following is not included in the key deliverable for the needs assessment stage of the building-block network design process, the set of logical network diagrams?

Specific routers that have been chosen to implement the proposed network

The traditional network design approach does not work well for ____ networks

rapidly growing

What information must the network manager identify?

The number and type of users and their locations

Which step in the network design process involves assessing the applications, users, and traffic that will use the network?v

Categorizing network needs

Which network component typically has the tightest security requirements in a network design?

core layer and data center

What is the main purpose of developing a request for proposal (RFP) when designing a network?

To specify the desired network equipment, software, and services

What is the turnpike effect?

An expression that means that traffic increases much faster than originally forecast

Upgrading a network is often much more expensive that building it right the first time

True

What is a bottleneck in a network?

A circuit that is filled almost to its capacity and thus is the critical point that determines whether users get good/bad response times. Most often it is the WAN and the Internet not the enterprise campus network

Network modeling and design tools can perform a number of functions. The first step is to___

Enter a diagram or model of the existing network or proposed network design. Other tools can “discover” the existing network.

Simulation in network design tools does what?

Used to model the behavior of the communication network.

What is the key deliverable?

A set of one or more physical network designs (usually more than one so we can compare technical trade off and costs)

What is the purpose of cost assessment and what are the main items of cost?

To assess the costs of physical network designs. Main items of cost are software, hardware, and circuits.

Estimating the cost of a network is not complex

False

What is a request for proposal (RFP)?

Organizations make these before developing large network purposes.

One of the main problems in network design is obtaining the support of senior management. What is the key to selling the proposal?

To management the network is a cost center. The key is speaking the managements language.

What are the deliverables of a network proposal?

1) an RFP that goes to vendors
2) revised physical network diagram
3) business case that provides support for the network desing expressed in business objectives

The component with the tightest security is usually the ______ and the ______

core layer; data center

Security for the enterprise edge is typically managed differently than security for the rest of the network

True

Each building has its own access and distribution layers and each building can be managed separately

True