1. Network Design and Implementation EEB_7_876
For MSc TeCNE and EDS

2. Methods of Teaching and Learning : Lectures and Workshops
Website:
Methods of Teaching and Learning : Lectures and Workshops
Assessment of the Module : 2-hour written examination -- 50% Two laboratory work reports %
Lecturer: Ya Bao and Perry Xiao.

3. Top-Down Network Design, 3rd Edition
Designing and Supporting Computer Networks (CCNA)
Priscilla Oppenheimer

4. Background Reading
Networking Systems Design and Development

5. Teaching calendar Network Programming (Week 1 – 6)
Network Design (Week 7 – 12)
Week 7, 8 Identifying Your Customer’s Needs and Goals
Week 8, 9 Logical Network Design
Week 10 Physical Network Design
Week 11 Testing, Optimizing and Documenting
Week 12 Review
Christmas vacation (3 weeks)
Revision (week 13)
Examination (week 14-15)

6. Part 1 Identifying Your Customer’s Needs and Goals
Analyzing Business Goals and Constraints
Analyzing Technical Goals and Tradeoffs
Characterizing the Existing Internetwork
Characterizing Network Traffic

7. Chapter One Analyzing Business Goals and Constraints
Systematic, Top-down network design methodology
Analysing your customer’s business objectives
Analysing the business constrains; budgets, timeframes, workplace politics.

8. Network Design
Good network design must recognizes customer’s requirements.
Network design choices and tradeoffs must be made when designing the logic network before any physical devices are selected.

9. Structured Network Design
Four fundamental network design goals:
Scalability
Availability
Security
Manageability
Graphic:

10. Network requirements:
How a Structured Network Design Creates a Stable, Reliable, Scalable Network
Network requirements:
Ease of management
Fast recovery
Application response time
Fast troubleshooting
Graphic:

11. Structured Network Design
Core Layer: connects Distribution Layer devices
Distribution Layer: interconnects smaller LANs
Access Layer: provides connections for hosts and end devices
Graphic: —run to end to show the three layers

12. Structured Network Design
Steps in network design projects:
Identify the network requirements
Characterize the existing network (for network upgrading only)
Design the network topology and solutions
Testing, optimizing and documenting
Graphic:

13. Start from the Top Application Presentation Session Transport Network
Data Link
Physical
Layer 1
Layer 7
Layer 6
Layer 5
Layer 4
Layer 3
Layer 2

14. Graphic:

15. Systems Development Life Cycles (SDLC)
Typical systems are developed and continue to exist over a period of time, often called a systems development life cycle (SDLC).

16. Top-Down Network Design Steps
systems development life cycle (SDLC).
Analyze requirements
Monitor and optimize network performance
Develop logical design
Develop physical design
Implement and test network
Typical systems are developed and continue to exist over a period of time, often called a systems development life cycle (SDLC).
Test, optimize, and document design

17. The PDIOO Network Life Cycle
Plan Design Implement Operate Optimize
Plan
Design
Retire
Optimize
Implement
Operate

18. Network Design Steps Phase 1 – Analyze Requirements Today’s topic
Analyze business goals and constraints
Analyze technical goals and tradeoffs
Characterize the existing network
Characterize network traffic

19. Network Design Steps Phase 2 – Logical Network Design
Design a network topology
Design models for addressing and naming
Select switching and routing protocols
Develop network security strategies
Develop network management strategies

20. Network Design Steps Phase 3 – Physical Network Design
Select technologies and devices for campus networks
Select technologies and devices for enterprise networks

21. Network Design Steps
Phase 4 – Testing, Optimizing, and Documenting the Network Design
Test the network design
Optimize the network design
Document the network design

22. Business Goals Increase revenue Reduce operating costs
Improve communications
Shorten product development cycle
Expand into worldwide markets
Build partnerships with other companies
Offer better customer support or new customer services

23. Recent Business Priorities
Mobility
Security
Resiliency (fault tolerance)
Business continuity after a disaster
Network projects must be prioritized based on fiscal goals
Networks must offer the low delay required for real-time applications such as VoIP
Resiliency means how much stress a network can handle and how quickly the network can rebound from problems, including security breaches, natural and unnatural disasters, human error, and catastrophic software or hardware failures.
Some experts, including Howard Berkowitz, have a mild dislike of the word “resiliency” as it sounds too much like a stretched rubber band or a trampoline. As Berkowitz says in his excellent book, WAN Survival Guide (Wiley 2001), “I avoid designing networks that stretch too far, bounce up and down, or oscillate between normal and backup states.”
So he likes “fault tolerance,” but he points out that it does not mean “immune to any conceivable threat.” Berkowitz states that, “A sufficient quantity of explosives can overcome the tolerance of any network.” :-)
fiscal
[ˈfɪsk(ə)l]
adjective
of or relating to government revenue, especially taxes

24. Business Constraints
Budget
Staffing
Schedule
Politics and policies

25. Collect Information Before the First Meeting
Before meeting with the client, whether internal or external, collect some basic business-related information
Such as
Products produced/Services supplied
Financial viability
Customers, suppliers, competitors
Competitive advantage

26. Meet With the Customer Try to get
A concise statement of the goals of the project
What problem are they trying to solve?
How will new technology help them be more successful in their business?
What must happen for the project to succeed?

27. Meet With the Customer Get a copy of the organization chart
This will show the general structure of the organization
It will suggest users to account for
It will suggest geographical locations to account for

28. Meet With the Customer Get a copy of the security policy
How does the policy affect the new design?
How does the new design affect the policy?
Is the policy so strict that you (the network designer) won’t be able to do your job?
Start cataloging network assets that security should protect
Hardware, software, applications, and data
Less obvious, but still important, intellectual property, trade secrets, and a company's reputation

29. The Scope of the Design Project
Small in scope?
Allow sales people to access network via a VPN
Large in scope?
An entire redesign of an enterprise network
Use the OSI model to clarify the scope
New financial reporting application versus new routing protocol versus new data link (wireless, for example)
Does the scope fit the budget, capabilities of staff and consultants, schedule?

30. Gather More Detailed Information
Applications
Now and after the project is completed
Include both productivity applications and system management applications
User communities
Data stores
Protocols
Current logical and physical architecture
Current performance
User communities, data stores, protocols, and the current architecture and performance will be discussed in the next few chapters. This chapter focuses on business needs and applications, which should be the first area of research in a top-down network design project. Network design is iterative, however, so many topics are addressed more than once as the designer gathers more detailed information and conducts more precise planning. So, gaining a general understanding of the size and location of user communities, for example, might be appropriate at this stage of the design project, but user communities should be investigated again when characterizing network traffic.

31. Summary Systematic approach
Focus first on business requirements and constraints, and applications
Gain an understanding of the customer’s corporate structure
Gain an understanding of the customer’s business style

32. Review Questions
What are the main phases of network design per the top-down network design approach?
What are the main phases of network design per the PDIOO approach?
Why is it important to understand your customer’s business style?
What are some typical business goals for organizations today?

33. Chapter Two Analyzing Technical Goals and Tradeoffs
Copyright 2010 Cisco Press & Priscilla Oppenheimer

34. Technical Goals Scalability Availability Performance Security
Manageability
Usability
Adaptability
Affordability
Your lab report should reflect some of these goals of your own designed network.
Scalability: How much growth a network design must support.
Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime.
Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented.
Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management
Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery.
Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes.
Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

35. Scalability Scalability refers to the ability to grow
Some technologies are more scalable
Flat network designs, for example, don’t scale well
Try to learn
Number of sites to be added
What will be needed at each of these sites
How many users will be added
How many more servers will be added

38. Availability
Availability can be expressed as a percent uptime per year, month, week, day, or hour, compared to the total time in that period
For example:
24/7 operation
Network is up for 165 hours in the 168-hour week
Availability is 98.21%
Different applications may require different levels
Some enterprises may want % or “Five Nines” availability

39. Availability
Availability can also be expressed as a mean time between failure (MTBF) and mean time to repair (MTTR)
Availability = MTBF/(MTBF + MTTR)
For example:
The network should not fail more than once every 4,000 hours (166 days) and it should be fixed within one hour
4,000/4,001 = 99.98% availability

40. Availability Downtime in Minutes
Per Hour
Per Day
Per Week
Per Year
99.999%
.0006
.01
.10 5
99.98%
.012
.29 2
105
99.95%
.03
.72 5
263
99.70% availability sounds pretty good, but it could mean that the network is down for 0.18 minutes every hour. This is 11 seconds. If those 11 seconds were spread out over the hour, nobody would notice possibly. But if there were some bug, for example, that caused the network to fail for 11 seconds every hour on the hour, people would notice. Users these days are very impatient.
Notice that 99.70% availability also could mean one catastrophic problem caused the network to be down for 1577 minutes all at once. That’s 26 hours. If it were on a Saturday and the network was never down for the rest of the year, that might actually be OK. So, you have to consider time frames with percent availability numbers.
Consider the holy grail: % availability. That’s 5 minutes downtime per year! Be sure to explain to the customer that scheduled maintenance and upgrades don’t count! Either that or plan for a network with triple redundancy (that could be extremely expensive to implement and operate).
99.90%
.06
1.44 10
526
99.70%
.18
4.32 30
1577(26 H)

41. 99.999% Availability May Require Triple Redundancy
ISP 1
ISP 2
ISP 3
Enterprise
In the event of failure of the primary router, the secondary becomes the primary and still has a backup. Fix the previous primary and have it become the tertiary.
This helps with maintenance too. Pull out the tertiary and upgrade it. The primary still has a backup. After extensive testing, put the tertiary back in as the primary. Pull out the original primary and upgrade it. Put it back as the secondary. Finally pull out the original secondary and upgrade it.
Of course, the picture brings up all sorts of other questions because it uses an ISP example.
Does the customer have provider independent addressing?
Does the customer have an autonomous system number?
Are the ISPs really independent? Is there true circuit diversity?
Are the speeds the same on the three links to the ISPs so that performance degradation is minimized during upgrades or failures?
Can load balancing be used when all three routers are operational?
What are the routing protocols inside the enterprise network? Can traffic really get to all three routers, regardless of failures inside the enterprise network? Can the routing protocols adjust to changes?
Will traffic flow out the “closest” router? Will traffic come in from the Internet via the “closest” entry?
Instructor note: The slide is not meant to be a design recommendation! It’s just a slide to get a discussion going on the ramifications of % availability.
Can the customer afford this?

42. Server Farms
Many enterprise networks provide users with Internet-accessible services, such as and e-commerce.
The availability and security of these services are crucial to the success of a business.
Managing and securing numerous distributed servers at various locations within a business network is difficult.
Recommended practice centralised servers in server farms. Server farms are typically located in computer rooms and data centres.

45. Benefits of creating a server farm
Network traffic enters and leaves the server farm at a defined point. This arrangement makes it easier to secure, filter and prioritise traffic.
Redundant, high-capacity links can be installed to the servers and between the server farm network and the main LAN. This configuration is more cost-effective than attempting to provide a similar level of connectivity to servers distributed throughout the network.
Load balancing and failover can be provided between servers and between networking devices.
The number of high-capacity switches and security devices is reduced, helping to lower the cost of providing services.

46. Network Performance Common performance factors include Bandwidth
Throughput
Bandwidth utilization
Offered load
Accuracy
Efficiency
Delay (latency) and delay variation
Response time

47. Bandwidth Vs. Throughput
Bandwidth and throughput are not the same
Bandwidth is the data carrying capacity of a circuit, fixed.
Usually specified in bits per second-bps
Throughput is the quantity of error free data transmitted per unit of time
Measured in bps, Bps, or packets per second (pps)
Depend on offered load, access method and error rate
Throughput < Bandwidth

48. Bandwidth, Throughput, Load
100 % of Capacity
Throughput
Actual
Ideal
100 % of Capacity
Offered Load

49. Other Factors that Affect Throughput
The size of packets
Inter-frame gaps between packets
Packets-per-second ratings of devices that forward packets
Client speed (CPU, memory, and HD access speeds)
Server speed (CPU, memory, and HD access speeds)
Network design
MAC Protocols (ALOHA 18.4%)
Distance
Errors
Time of day, etc., etc., etc.

50. Throughput Vs. Goodput
Are you referring to bytes per second, regardless of whether the bytes are user data bytes or packet header bytes
Or are you concerned with application-layer throughput of user bytes, sometimes called “goodput”
In that case, you have to consider that bandwidth is being “wasted” by the headers in every packet

51. Performance (continued)
Efficiency
How much overhead is required to deliver an amount of data?
How large can packets be?
Larger better for efficiency (and goodput)
But too large means too much data is lost if a packet is damaged
How many packets can be sent in one bunch without an acknowledgment?

52. Efficiency
Small Frames (Less Efficient)
Large Frames (More Efficient)

53. Delay from the User’s Point of View
Response Time
A function of the application and the equipment the application is running on, not just the network
Most users expect to see something on the screen in 100 to 200 milliseconds

54. Delay from the Engineer’s Point of View
Propagation delay
A signal travels in a cable at about 2/3 the speed of light in a vacuum (3×108 m/s)
Transmission delay (also known as serialization delay)
Time to put digital data onto a transmission line
For example, it takes about 5 ms to output a 1,024 byte packet on a Mbps T1 line
Packet-switching delay
Queuing delay

55. Queuing Delay and Bandwidth Utilization
Number of packets in a queue increases exponentially as utilization increases
Queue depth = utilization/(1- utilization)

56. Example
A packet switch has 5 users, each offering packets at a rate of 10 packets per second
The average length of the packets is 1,024 bits
The packet switch needs to transmit this data over a 56-Kbps WAN circuit
Load = 5 x 10 x 1,024 = 51,200 bps
Utilization = 51,200/56,000 = 91.4%
Average number of packets in queue =
(0.914)/( ) = packets

57. Security Focus on requirements first
Detailed security planning later (Chapter 8)
Identify network assets
Including their value and the expected cost associated with losing them due to a security problem
Analyze security risks

58. Manageability Fault management Configuration management
Accounting management
Performance management
Security management

59. Usability
Usability: the ease of use with which network users can access the network and services
Networks should make users’ jobs easier
Some design decisions will have a negative affect on usability:
Strict security, for example

60. Adaptability
Avoid incorporating any design elements that would make it hard to implement new technologies in the future
Change can come in the form of new protocols, new business practices, new fiscal goals, new legislation
A flexible design can adapt to changing traffic patterns and Quality of Service (QoS) requirements

61. Affordability
A network should carry the maximum amount of traffic possible for a given financial cost
Affordability is especially important in campus network designs
WANs are expected to cost more, but costs can be reduced with the proper use of technology
Quiet routing protocols, for example

62. Making Tradeoffs (example)
Scalability 20
Availability 30
Network performance 15
Security
Manageability
Usability
Adaptability
Affordability
Total (must add up to 100) 100

63. Summary Continue to use a systematic, top-down approach
Don’t select products until you understand goals for scalability, availability, performance, security, manageability, usability, adaptability, and affordability
Tradeoffs are almost always necessary

64. Review Questions
What are some typical technical goals for organizations today?
How do bandwidth and throughput differ?
How can one improve network efficiency?
What tradeoffs may be necessary in order to improve network efficiency?

65. Chapter Three Characterizing the Existing Internetwork
Copyright 2010 Cisco Press & Priscilla Oppenheimer

66. What’s the Starting Point?
According to Abraham Lincoln:
“If we could first know where we are and whither we are tending, we could better judge what to do and how to do it.”
whither
interrogative adverb
to what place

67. Where Are We? Characterize the exiting internetwork in terms of:
Its infrastructure
Logical structure (modularity, hierarchy, topology)
Physical structure
Addressing and naming
Wiring and media
Architectural and environmental constraints
Health

68. Diagram a Physical Network and Document the Existing Network
Network documentation:
Logical and physical diagrams
Floor plans
Complete lists for equipments and applications
Current network configuration files
inventory
[ˈɪnv(ə)nt(ə)ri]
(pl. -ies)
a complete list of items such as property, goods in stock, or the contents of a building

69. Get a Network Map (physical)
Medford
Fast Ethernet
50 users
Roseburg
Fast Ethernet
30 users
Frame Relay
CIR = 56 Kbps
DLCI = 5
Frame Relay
CIR = 56 Kbps
DLCI = 4
Gigabit Ethernet
Grants Pass HQ
Gigabit Ethernet
Grants Pass HQ
Fast Ethernet
75 users
FEP (Front End Processor)
IBM Mainframe T1
Web/FTP server
Eugene
Ethernet
20 users T1
Internet

70. Diagram a Physical Network and Document the Existing Network
Identify and document the strengths and weaknesses of the existing network
Focus on finding ways to overcome weaknesses
Stateful firewall
From Wikipedia, the free encyclopedia
Jump to: navigation, search
In computing, a stateful firewall (any firewall that performs stateful packet inspection (SPI) or stateful inspection) is a firewall that keeps track of the state of network connections (such as TCP streams, UDP communication) traveling across it. The firewall is programmed to distinguish legitimate packets for different types of connections. Only packets matching a known active connection will be allowed by the firewall; others will be rejected.

72. Characterize Addressing and Naming
IP addressing for major devices, client networks, server networks, and so on
Any addressing oddities, such as discontiguous subnets?
Any strategies for addressing and naming?
For example, sites may be named using airport codes
San Francisco = SFO, Oakland = OAK
In LSBU, T-tower block; K-keyworth building; B-Borough road building; L- london road building

73. Discontinuous Subnets – make problems for some routing protocols
Area 0
Network
Router A
Router B
Area 1
Subnets
Area 2
Subnets

74. Characterize the Wiring and Media
Single-mode fiber
Multi-mode fiber
Shielded twisted pair (STP) copper
Unshielded-twisted-pair (UTP) copper
Coaxial cable
Microwave
Laser
Radio
Infra-red

75. Architectural Constraints
Make sure the following are sufficient
Air conditioning
Heating
Ventilation
Power
Protection from electromagnetic interference
Doors that can lock

76. Architectural Constraints
Make sure there’s space for:
Cabling conduits
Patch panels
Equipment racks
Work areas for technicians installing and troubleshooting equipment

78. Check the Health of the Existing Internetwork
Performance
Availability
Bandwidth utilization
Accuracy
Efficiency
Response time
Status of major routers, switches, and firewalls

79. Characterize Availability
Cause of Last Major Downtime
Date and Duration of Last Major Downtime
Fix for Last Major Downtime
MTBF
MTTR
Enterprise
Segment 1
Segment 2
Segment n
Mean time between failures (MTBF)
Mean time to recovery (MTTR)

80. Network Utilization in Minute Intervals

81. Network Utilization in Hour Intervals

82. Bandwidth Utilization by Protocol
Relative Network Utilization
Absolute Network Utilization
Broadcast Rate
Multicast Rate
Protocol 1
Protocol 2
Protocol 3
Protocol n
Relative usage specifies how much bandwidth is used by the protocol in comparison to the total bandwidth currently in use on the segment. Absolute usage specifies how much bandwidth is used by the protocol in comparison to the total capacity of the segment (for example, in comparison to 100 Mbps on Fast Ethernet).

83. Characterize Packet Sizes

84. Characterize Response Time
Node A
Node B
Node C
Node D
Node A
Node B
Node C
Node D X X X X

85. Check the Status of Major Routers, Switches, and Firewalls
show buffers
show environment
show interfaces
show memory
show processes
show running-config
show version
Use Cisco IOS show command

86. Tools Protocol analyzers Multi Router Traffic Grapher (MRTG)
Remote monitoring (RMON) probes
Cisco Discovery Protocol (CDP)
Cisco IOS NetFlow technology
CiscoWorks

87. Summary
Characterize the exiting internetwork before designing enhancements
Helps you verify that a customer’s design goals are realistic
Helps you locate where new equipment will go
Helps you cover yourself if the new network has problems due to unresolved problems in the old network

88. Review Questions
What factors will help you decide if the existing internetwork is in good enough shape to support new enhancements?
When considering protocol behavior, what is the difference between relative network utilization and absolute network utilization?
Why should you characterize the logical structure of an internetwork and not just the physical structure?
What architectural and environmental factors should you consider for a new wireless installation?

89. Chapter Four Characterizing Network Traffic
Copyright 2010 Cisco Press & Priscilla Oppenheimer

90. Network Traffic Factors
Traffic flow
Location of traffic sources and data stores
Traffic load
Traffic behavior
Quality of Service (QoS) requirements

91. User Communities, a set of worker who use a particular application or set of applications.
User Community Name
Size of Community (Number of Users)
Location(s) of Community
Application(s) Used by Community

92. Data Stores (sinks), an area in a network where application layer data resides. Server, or any device where large quantities of data are stored.
Data Store
Location
Application(s)
Used by User Community(or Communities)

93. Traffic Flow, involves identifying and characterizing individual traffic flows between traffic source and stores.
Destination 1 Destination 2 Destination 3 Destination MB/sec MB/sec MB/sec MB/sec
Source 1
Source 2
Source 3
Source n

94. Library and Computing Center Business and Social Sciences
Traffic Flow Example
10-Mbps Metro Ethernet to Internet
30 Library Patrons (PCs)
30 Macs and 60 PCs in Computing Center
App Kbps
App Kbps
App Kbps
App Kbps
App Kbps
Total 808 Kbps
Server Farm
App Kbps
App Kbps
App Kbps
App Kbps
Total 220 Kbps
25 Macs
50 PCs
50 PCs
Arts and Humanities
Administration
App Kbps
App Kbps
App Kbps
App Kbps
Total 126 Kbps
App Kbps
App Kbps
App Kbps
App Kbps
App Kbps
App Kbps
App Kbps
Total 1900 Kbps
Math and Sciences
30 PCs
50 PCs
Business and Social Sciences

95. Types of Traffic Flow Terminal/host Client/server Thin client
Peer-to-peer
Server/server
Distributed computing

96. Traffic Flow for Voice over IP
The flow associated with transmitting the audio voice is separate from the flows associated with call setup and teardown.
The flow for transmitting the digital voice is essentially peer-to-peer.
Call setup and teardown is a client/server flow
A phone needs to talk to a server or phone switch that understands phone numbers, IP addresses, capabilities negotiation, and so on.

97. Identifying Application Impacts on Network Design
File transfer and applications:
Unpredictable bandwidth usage
Large packet size
Centralization of file and mail servers in a secure location
Redundancy to ensure reliable service
Graphic:

98. Identifying Application Impacts on Network Design
HTTP and web traffic:
Network media
Redundancy
Security
Graphic:

99. Network Applications Traffic Characteristics
Name of Application
Type of Traffic Flow
Protocol(s) Used by Application
User Communities That Use the Application
Data Stores (Servers, Hosts, and so on)
Approximate Bandwidth Requirements
QoS Requirements

100. Traffic Load
To calculate whether capacity is sufficient, you should know:
The number of stations
The average time that a station is idle between sending frames
The time required to transmit a message once medium access is gained
That level of detailed information can be hard to gather, however

101. Size of Objects on Networks
Terminal screen: 4 Kbytes
Simple 10 Kbytes
Simple web page: 50 Kbytes
High-quality image: 50Mbytes
Database backup: 1Gbytes or more

102. Traffic Behavior Broadcasts Multicasts
All ones data-link layer destination address
FF: FF: FF: FF: FF: FF
Doesn’t necessarily use huge amounts of bandwidth
But does disturb every CPU in the broadcast domain
Multicasts
First bit sent is a one
01:00:0C:CC:CC:CC (Cisco Discovery Protocol)
Should just disturb NICs that have registered to receive it
Requires multicast routing protocol on internetworks

103. Network Efficiency Frame size Protocol interaction
Windowing and flow control
Error-recovery mechanisms

104. QoS Requirements ATM service specifications Constant bit rate (CBR)
Realtime variable bit rate (rt-VBR)
Non-realtime variable bit rate (nrt-VBR)
Unspecified bit rate (UBR)
Available bit rate (ABR)
Guaranteed frame rate (GFR)

105. QoS Requirements per IETF (Internet Engineering Task Force, develops and promotes Internet standards, It is an open standards organization, with no formal membership or membership requirements.)
IETF integrated services working group specifications
Controlled load service
Provides client data flow with a QoS closely approximating the QoS that same flow would receive on an unloaded network
Guaranteed service
Provides firm (mathematically provable) bounds on end-to-end packet-queuing delays
Internet Engineering Task Force The Internet Engineering Task Force (IETF) develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standards bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite. It is an open standards organization, with no formal membership or membership requirements.

106. QoS Requirements per IETF
IETF differentiated services working group specifications
RFC 2475
IP packets can be marked with a differentiated services codepoint (DSCP) to influence queuing and packet-dropping decisions for IP datagrams on an output interface of a router

107. How Quality of Service is Implemented on the LAN/WAN
Where QoS can be implemented to affect traffic flow:
Layer 2 devices
Layer 3 devices
Graphic:

108. Document the Network Requirements of Specific Categories of Applications
Estimate the volume of application traffic during the initial design phase.
Document projected applications and associated hardware in a network diagram.
Graphic:

109. Summary Continue to use a systematic, top-down approach
Don’t select products until you understand network traffic in terms of:
Flow
Load
Behavior
QoS requirements

110. Review Questions
List and describe six different types of traffic flows.
What makes traffic flow in voice over IP networks challenging to characterize and plan for?
Why should you be concerned about broadcast traffic?
How do ATM and IETF specifications for QoS differ?

111. of Part 1