Design Teams and Translating
Plans into Design Criteria
IACT 424 IACT 924
Corporate Network Design and
Implementation
Summary Slide
• Design Criteria
• An Architectural Approach to Network
Design
• Four(4) Guiding Principles
• Legacy System Analysis
• Creating Design Teams
2
Design Criteria
• Design criteria are the explicit goals that a
project must achieve in order to be successful
– In recommendation and feasibility reports the
design and decision criteria determine the
document's final recommendation for action
– Managers use these criteria as their basic tool in
evaluating a project's potential for success and
how well it fits into the goals of the organization
– Experts need explicit design and decision criteria in
order to evaluate recommended designs of devices
and test procedures.
3
Design Criteria
• Primary criteria are those that constitute
a successful project
– the project will be unsuccessful if it does
not meet these goals
• Secondary criteria are those features
that are highly desirable but not
absolutely essential
4
Design Criteria
• Separating primary and secondary
criteria establishes a clear hierarchy in
design choices
– Implementing one criterion makes the
implementation of another infeasible or
costly
– A secondary criterion may be sacrificed in
favour of a primary criterion.
5
Design Criteria
• Make your design criteria short but as specific
as possible
– Avoid vague language
– List your primary criteria first
– Then list the secondary criteria
• Design criteria are often best displayed in
bulleted lists
– Short titles preceding the explanation
– These titles may then be used later in the
document to refer to the specific criteria being
discussed
6
Design Criteria
• If you number your criteria
– Avoid referring to them later solely by
number
– This practice often confuses readers
• Use tables to show and summarize the
relative effectiveness of different
implementations in comparison with
your design criteria
7
An Architectural Approach to
Network Design
• Should not be confused with a detail design of
the network
• Architectural design is a term that defines
– Technologies
– Protocols
– Communication capabilities
– Generic products
– interconnection of segments of a network
8
An Architectural Approach to
Network Design
• Architectural design
– Supports the network concepts developed
– Expands on the conceptual design
• Where organisation-wide strategic directions
are set and defined
• These are used as a way to identify the network
design criteria
– criteria that are in line with the organisations direction
and technology evolution
9
An Architectural Approach to Network
Design – Major Considerations
• Development of
– The conceptual design
• Linked with detailed research on
– The business characteristics and process of the
organisation
– The competition the business is facing
• Particularly electronically
– What new customer interaction channels are
required
10
An Architectural Approach to Network
Design – Major Considerations
• General technology trends
– Technology choices
– Lifespan of all technologies that might be
utilised in the architecture
• User types
– Current and planned
– Need to be defined
11
An Architectural Approach to Network
Design – Major Considerations
• Security requirements in the form of an
enterprise security policy developed
• Current, planned and the potential
geographic reach of the network which
– Including locations, users and customer/
partner organisations
• Definition and identification of
applications that run over the converged
network
12
An Architectural Approach to Network
Design – Major Considerations
• Analysis of
– Current capacity of the network
– Future requirements
• Based on
– Services
– Reach
– Applications
– Users
13
An Architectural Approach to Network
Design – Major Considerations
• These will provide
– A streamlined design process
– Alignment of the network capability with
current and future business requirements
14
Outcomes of an Architectural
Design
• The architectural design will produce a
number of outcomes
– Design directions
– Architecture outline/ overview diagrams for the
network segments detailing technology and
features/functions.
• The architecture design will
– Outline high level network topology
– Detail interconnections of the network segments
– Identify the protocols that will be used
15
Network Architectural Design –
Elements
• Design elements fall into two categories
– Concept elements
• Architecture concepts (characteristics)
– Technology elements
16
Concept Elements
• Business environment
– Business developments and direction
– New competitors and competitor channels
– Current and emerging customer interaction
channels
• Technology
– Available protocol choices
– Available/suitable generic product choices (groups)
– Ancillary/complementary technologies
– Business applications
17
Concept Elements
• Scalability
– Scalability defined at network segment(s) level
– Scalability rules and limits
• Dependability
– Availability requirements
– Recoverability parameters/requirements
– Survivability requirements
– Fault tolerance requirements
18
Concept Elements
• Security
– Security requirements (rules and limits set
at each network segment level)
– Security requirements for user types
• Management and maintainability
– Management system requirements
– Maintainability functions, restore
requirements
19
Concept Elements
• Compatibility
– Compatibility requirements
– Compatibility rules between segments
– Legacy equipment, systems and protocols
• Limitations
– Limits for size of network
– Limits for volume
– Traffic types and traffic mix
20
Concept Elements
• Flexibility
– Future reach
– User demographics and potential changes
– Services deployment intent
• Distribution and geography
– Geographic boundaries of the network (eg
distance, location)
– Traffic distribution rules (based on geography)
21
Concept Elements
• Optimisation and financials
– Cost ranges for network, operational and
capital
– Service dependability versus cost ranges
• Risks
– Business environment risk
– Technology risks (early, lifecycle)
– Costs (equipment, installation, operational)
22
Concept Elements
• Performance
– Objectives for delay/latency
– Network throughputs
– Potential and identified impairments
• Simplicity
– Protocol type reduction
– Configuration parameter reduction
23
Network Components
• Nodes
– Node types
– Assignment/identification of generic
products for node types
• Links
– Network link types
– Assignment/identification of generic
products for link types
24
Network Components
• Topology
– Node distribution, interconnection
– Network topology for control and management,
interconnections
• Interfaces
– Applications and users
– Other networks
– Interface technology types
– Protocols
25
Network Components
• Services
– Communication services types (focus on
latency sensitive)
– Security services
– Management services
– Mapping/overlaying services to network
topology
26
Network Components
• Protocols
– Protocols for transport
– Protocols for nodes
– Protocols for interfaces
• Traffic mapping
– Segmentation
– QoS dependencies
– Bandwidth/volumes
27
Four(4) Guiding Principles
• The task of writing the design document needs to be
guided by the following
– Functionality: will the end product work?
– Scalability: is the network able to grow without major
problems
– Adaptability: will the project be able to incorporate new
technologies in the future?
– Manageability: can we monitor network operations and make
necessary changes easily?
• May also wish to consider
– Standards Compliance
– Security
– Reduced Institutional Risk
28
Functionality
• Functionality:
– Does the network support each job function
so that strategic goals can be attained?
– Does the network deliver end-to-end
connectivity that is both reliable and
sufficiently fast
29
Scalability
• Any network design must allow for future
growth
• In physical terms, this means
– Allowing space in equipment racks for more
equipment
– Spare connection points in main and intermediate
distribution frames (MDFs and IDFs)
• In logical terms, well structured IP addressing
schemes
30
Adaptability
• Design Criteria should incorporate
possible changes to design through the
advent of new technology
• The design should not have features
that makes the future provisioning of
new technology impossible
31
Manageability
• The network should facilitate both
monitoring and manageability
32
A Closer Look at Design
Requirements
• Two important sources of information should be
exploited
– The Design Requirements section of your Design Document
is a summary of requirements that have been developed
during your strategic analysis phase.
– It also draws on past experience by
• Describing the existing network (legacy system)
• Listing current applications, protocols, users
• Describing the current performance of the network
• Brings together all the knowledge that will be used to
develop next section, the Design Solution.
33
Characterising the Network
• Strategic objectives are used to:
– Specify business goals, business processes,
customers, suppliers. This has implications for
functionality.
– Define corporate structure. This has implications
for LAN and VLAN design where networks
servicing different workgroups need to be
separated.
– Define geographic structure. This has implications
for where workgroups, suppliers, customers are
physically located. Mostly relevant to determining
WAN typologies.
34
Legacy System Analysis
• Identify currently used applications
– Necessary in determining how work is
currently carried out in the organisation
• Information flows should be documented
– Including those that are transferred in hard
copy, on discs or verbally
35
Legacy System Analysis
• New designs have the potential to disrupt
established information sharing relationships
between people
• Shared data sources should be identified
– Policy manuals
– Servers
– Intranets
– Bulletin boards
36
Legacy System Analysis
• Determine network traffic and access
– Identify the amount of data that travels
within segments and between segments
– Determine the volumes of data that are
obtained externally from the Internet.
• Determine network performance
• Identify protocols in use
37
Network Performance Guide
(Teare, 1999)
• No shared Ethernet segment to be
saturated (no more than 40% network
utilisation)
• No shared Token Ring segments are
saturated (no more than 70% network
utilisation)
• No WAN links are saturated (no more
than 70% network utilisation)
38
Network Performance Guide
(Teare, 1999)
• Response time <100 milliseconds
• No segment have more than 20%
broadcasts/multicasts
• No segments have more than one CRC
(Cyclic Redundancy Check) error per million
bytes of data
• On Ethernet segments, less than 0.1 % of
packets result in collisions
• On the Token Ring segments, less than 0.1%
of the packets are soft errors not related to
ring insertion
39
Network Performance Guide
(Teare, 1999)
• On FFDI segments, there has been no
more than one ring operation per hour
not related to ring insertion
• Routers are not over-utilised (5 minute
CPU utilisation no more than 75%
• The number of output queue drops has
not exceeded more than 100 in any hour
on any router
40
Network Performance Guide
(Teare, 1999)
• The number of input queue drops has
not exceeded more than 50 in any hour
on any router
• The number of buffer misses has not
exceeded more than 25 in an hour on
any router
• The number of ignored packets has not
exceeded more than 10 in an hour on
any interface on a router
41
Creating Design Teams
• Different skills are required of project
leaders through the life of a project.
• In the early stages, the emphasis should
be on leadership
• In the later stages, the emphasis should
be on management
42
Leadership and
Management (Verma, 1996, p. 223)
Leaders focus on
Vision
Selling what and why
Longer range
People
Democracy
Enabling
Developing
Challenging
Originating
Innovating
Directing
Policy
Flexibility
Risk (opportunity)
43
Managers focus on
Objectives
Telling how and when
Shorter range
Organisation & structure
Autocracy
Restraining
Maintaining
Conforming
Imitating
Administering
Controlling
Procedures
Consistency
Risk avoidance
The people you’ll need
• Telecommunications Manager
– Conceptualiser & visionary
– Articulate & persuasive
– Understand organisations problems & how
communications tech can be applied to them
– Able to grasp technical subjects but doesn’t have
to be a ‘techie’
– Able to plan & make decisions
44
The people you’ll need
• Designers & Implementers
– Good understanding of communications
systems & products
– Creative & innovative
– Project management skills
– Verbal & written communications skills
– Team player
45
The people you’ll need
• Network operations staff
– the ‘manufacturing’ arm
– Service oriented
– Strongly motivated to maintain the system
– Good verbal skills with ‘customers’
– Able to swap between sections (say:
network ops & computer ops) to spread
skills and experience
46
The people you’ll need
• Technical support staff
– Understand hardware & software
– Self-starters
– Analytical problem solvers
– Often have advanced technical education,
frequently vendor based
• Novel
• Microsoft
• Cisco etc.
47
The people you’ll need
• Administrative support staff
– Largely clerical
– Some grasp of IT issues & jargon
– Accounting & business administration skills
48