Chapter 8 - Network Analysis and Design

Question 1

Network Architecture Components

Answer 1

• 7 components max:
  – LAN (Ch. 7)
  – Building BBN (Ch. 8)
  – Campus BBN (Ch.8)
  – Data center (special purpose LANs covered in Ch. 7)
  – Enterprise edge
• WAN/MAN (Ch. 9)
• Internet access (Ch. 10)
• e-commerce edge (Ch. 7)

Question 2

Core layer not needed when:

Answer 2

Network limited to one building

Question 3

Core layer and distribution layer combined:

Answer 3

Two-tier model can be suitable for small to medium-size campus networks

Question 4

The traditional approach: NDLC (Similar to SDLC(Software Development Life Cycle)

Answer 4

– Planning + Analysis + Design + Implementation + Maintenance
– Limitations:
* (Precise) planning is time consuming and not necessary: Networks need to be upgraded / replaced more frequently than IS, some networking technology change rapidly and network traffic grows rapidly
* Maintenance: Responsibility of network manager not network designer

Question 5

The building Block Process

Answer 5

Uses standard components to simplify design and management

Has three phases:
– Needs analysis
– Technology design
– Cost assessment

To reach the final design:
– Perform Needs Analysis & Technology Design phases
– Complete initial cost assessment
* Over budget? Refine the needs analysis THEN cycle through all three phases again AND when the design meets requirements and fits budget send RFP to vendor(s)
* Within budget? Send RFP to vendor(s)

Question 6

Needs analysis

Answer 6

Purpose: Analyze network users’ needs and define the requirements of network applications

Question 7

Baselining Task:

Answer 7

Measure / record features of existing network over periods of time to create metrics of current operations to compare new design against.

Questions: Which metrics should be created? What if this a newly founded organization?

Question 8

Network architecture components Task:

Answer 8

Break the network into access, distribution and possibly core layers, MAN/WAN, Internet access, e-Commerce Edge and data center.

Question 9

Application systems Task:

Answer 9

Identify applications used in /required for the new network

Question 10

Network users Task:

Answer 10

Identify who uses which applications, how they access them (i.e., using wired or
wireless LANs), their location, effect on level of traffic

Question 11

Needs categorization:

Answer 11

• Assess traffic in each segment: Typical (100 Mbps) v/s high (or multimedia, 1000Mbps)
• Organize network applications requirements: Mandatory v/s desirable v/s wish list

Question 12

Deliverable: The logical network design

Answer 12

– Describes what network elements will be needed to meet organization’s needs
– Shows categorized applications, layers and traffic

Question 13

Design Clients and Servers:

Answer 13

Application architecture (C/S vs Host-based), type of C/S architecture, type of “clients” and “servers”, their configuration
- Determine hardware and software requirements for workstations and servers used on network
- Selecting appropriate operating systems, applications, and hardware components…

Question 14

Design circuits:

Answer 14

• Decide on LAN technology (Ethernet or Ethernet-compatible), topologies (switches and APs), form of BBNs (switches, routers, VLAN switches) and type of cabling (TP vs Fiber)
• Do capacity planning i.e, decide on nominal data rates (100Mbps, 1Gbps etc.). This requires assessing circuit loading i.e., the amount of data transferred across a circuit currently and in the future in terms of average traffic vs peak traffic (and designing for peak traffic is ideal!).

Traffic typically increases more than anticipated (turnpike effect) and precision may not be a major concern due to the “stair step” nature of nominal data rates available for Ethernet (100Mbps, 1Gbps) BUT cost increases SHARPLY after 1Gbps
Should network designers plan for excess capacity? Upgrading costs 50-80% more than designing for higher capacity the first time but cost increases sharply after 1Gbps

Question 15

Modeling (and documenting):

Answer 15

Designers create diagrams of existing or proposed networks

Question 16

Simulating (Technology Design Tasks)

Answer 16

Designers then model the behavior of a network under specific conditions to simulate applications and users generating traffic and highlight potential problems

Question 17

Deliverable: The physical network design

Answer 17

– Describes specs of network elements (computers, intermediary devices, cabling, etc.) needed to meet organization’s needs
– Normally, more than one physical network designs are prepared to show tradeoff between performance (or other technical goals) and cost

Question 18

Cost assessment

Answer 18

Purpose: Assess cost of various network design alternatives

• Tasks: Include in the assessment various costs such as the
  – Circuit costs (cabling and installation)
  – Internetworking devices (switches, APs and routers)
  – Hardware costs (clients, servers, printers, power supplies, backup tapes, etc.)
  – Software costs (operating systems, application software and middleware)
  – Network management and maintenance costs (monitoring equipment, training costs)
  – MAN, WAN and Internet services

Question 19

Request for Proposal (RFP)

Answer 19

• The RFP creates a competitive environment for providing network equipment and services
• Multi-vendor selections have the advantage of maintaining alternative equipment and services sources, but are also more difficult to manage➔One RFP sent to leader in the industry

Question 20

Request for Proposal Contains:

Answer 20

• Background Information
• Network Requirements
• Service Requirements
• Bidding Process
• Information Required from Vendor

Question 21

Business Case

Answer 21

• Purpose: Obtain support of senior management
• Presenting the design with focus on:
  – Organizational needs
  – Business objectives
  – Increase in volume of traffic vs increase in budget – Best practices