Hw design methodologies

Question 1

The Network Design Process

Answer 1

The network development life cycle depends on previously
completed development processes such as strategic business
planning, applications development life cycle, and data distribution
analysis.

Question 2

Design Requirements

Answer 2

• Business goals explain the role the network design will
play in helping an organization succeed

• Technical goals include scalability, performance,
security, manageability, usability, adaptability, and
affordability

Question 3

Network Development Life Cycle

Answer 3

• Analyze requirements:
– Interviews with users and technical personnel
– Understand business and technical goals for a new or enhanced
system
– Characterize the existing network: logical and physical
topology, and network performance
– Analyze current and future network traffic, including traffic flow
and load, protocol behavior, and QoS requirements

• Develop the logical design:
– Deals with a logical topology for the new or enhanced network
– Network layer addressing and naming
– Switching and routing protocols
– Security planning
– Network management design
– Initial investigation into which service providers can meet WAN and
remote access requirements

• Develop the physical design:
– Specific technologies and products to realize the logical design are
selected
– The investigation into service providers must be completed during
this phase

• Test, optimize, and document the design:
– Write and implement a test plan
– Build a prototype or pilot
– Optimize the network design

Question 4

Top-Down Network Design

Answer 4

Don’t just start connecting the dots.
Analyze business and technical goals first.
Explore divisional and group structures to find out who the
network serves and where they reside.
Determine what applications will run on the network and
how those applications behave on a network.
Focus on Layer 7 and above first.

Question 5

(Dis)Advantages of Top Down Design

Answer 5

Decisions can be made and implemented very quickly.
This is particularly important when time is limited.
The other benefit of top-down project planning is that it helps align the project
goals with the organization’s strategic goals as upper management is giving the
directions

DIS
Low participation (this is likely to influence the implementation of the plans in a
negative way).
Requires a lot of knowledge at the top level.
Does not use specialized knowledge which may be present in the lower echelons
of the organization.

Question 6

Bootom-Up Approach

Answer 6

This approach begins with the physical layer of the OSI
model and works its way up.
New, higher bandwidth links might be purchased, as well
as new routers, switches, firewalls, etc.
Designing a network with a bottom-up approach enables
you to get your network set up much faster

Question 7

PDIOO Network Life Cycle

Answer 7

Prepare – establish organizational
requirements.
Plan – identify initial network
requirements.
Design – comprehensive, based on
planning outcomes.
Implement – build network according
to design.
Operate – maintain network health.
Optimize – proactive management of
network.

Question 8

PDIOO Network Life Cycle

Answer 8

• Plan:
– Network requirements are identified in this phase
– Analysis of areas where the network will be installed
– Identification of users who will require network services

• Design:
– Accomplish the logical and physical design, according to
requirements gathered during the Plan phase

• Implement:
– Network is built according to the Design specifications
– Implementation also serves to verify the design

• Operate:
– Operation is the final test of the effectiveness of the design
– The network is monitored during this phase for performance
problems and any faults, to provide input into the Optimize phase

• Optimize:
– Based on proactive network management which identifies and
resolves problems before network disruptions arise
– The optimize phase may lead to a network redesign
• if too many problems arise due to design errors, or
• as network performance degrades over time as actual use and
capabilities diverge
– Redesign may also be required when requirements change
significantly

Retirement
Although not technically part of the PDIOO process, the
retirement of the network—or parts of the network—is a
natural progression in the life cycle of a network.
As new technology develops and needs evolve, all or part
of the network often becomes obsolete.
The outdated equipment is then either retired or
repositioned somewhere else in the network where the
demands on it won’t overwhelm its limited capacity.