Network Performance Models Overview

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Questions and Answers

What is the maximum Round Trip Time (RTT) requirement mentioned?

100 msec (correct)

200 msec

50 msec

150 msec

Which service level is characterized by high capacity and reliability?

Platinum (correct)

Basic

Silver

Gold

What needs to be ensured for services to be configurable and verifiable?

The user-server connection should not be measured.

All services must be understood at basic levels.

Only the top network components must be monitored.

Service metrics must be applied across all network components. (correct)

Which characteristic is NOT mentioned as part of service metrics?

Network Security Signup and view all the answers

An example of a service metric characteristic would include:

Round-Trip delay Signup and view all the answers

In service levels, which option is defined as having no priority?

Basic Signup and view all the answers

Capacity in service metrics refers to what measurement?

The amount of data transmitted over a network in a given time. Signup and view all the answers

What is implied by the term 'service levels'?

It groups various service characteristics into categories. Signup and view all the answers

What is the main characteristic of Best Effort performance?

It allows for maximum traffic flows but may reduce performance. Signup and view all the answers

In a Guaranteed performance network with Call Admission Control (CAC), what happens when system resources are fully loaded?

No more calls are allowed until resources become available. Signup and view all the answers

What is the difference between Best Effort and Guaranteed performance in networking?

Best Effort performance does not ensure an acceptable level of service. Signup and view all the answers

Why might many applications require a hybrid of Best Effort and Guaranteed performance?

They need predictable performance along with flexibility in traffic flow. Signup and view all the answers

What refers to the interconnecting of the network at different levels to achieve improved performance?

Diversity Signup and view all the answers

At which point does congestion begin to load the network in Best Effort performance?

When throughput falls below 50 Mb/s. Signup and view all the answers

In a Flat Bridged or Switched Network, what is the main issue that arises?

Lack of hierarchy Signup and view all the answers

What is the maximum traffic capacity shown for Fast Ethernet performance in the provided graph?

100 Mb/s Signup and view all the answers

What does the term 'Predictable Effort' refer to?

A mixture of Best Effort and Guaranteed performance. Signup and view all the answers

Which of the following levels is NOT part of the network and system complexity generations?

5th Generation – AI Integration Signup and view all the answers

What does a Content Delivery Network (CDN) primarily provide?

Direct connectivity Signup and view all the answers

What is likely to occur when new traffic flows are added in a Best Effort network?

Performance degradation is likely. Signup and view all the answers

What is a common challenge found in the architecture and design of networks?

Overlooked data gathering Signup and view all the answers

What type of network architecture consists of multiple broadcast domains?

Hierarchical Network Signup and view all the answers

Which generation of network complexity focuses on connectivity?

1st Generation Signup and view all the answers

What is one of the primary reasons for implementing a hierarchy in network design?

To force flows through hierarchy Signup and view all the answers

What is the primary focus of network analysis?

Understanding the existing state and problems of the network Signup and view all the answers

Which aspect is NOT included in network architecture?

Physical connectivity choices Signup and view all the answers

Which model focuses on the physical details of a network?

Physical Model Signup and view all the answers

What do relationships within network architecture emphasize?

Interactions and trade-offs between functions Signup and view all the answers

Which of these is NOT a component of network design?

Evaluating network protocols Signup and view all the answers

Which statement best describes the goal of network goals in analysis?

To define expectations and performance metrics of users Signup and view all the answers

What is primarily assessed in the initial stage of a network analysis?

The state and existing problems of the network Signup and view all the answers

What do mappings of applications and devices in network analysis focus on?

Understanding how components interact within the network Signup and view all the answers

What is primarily lost when decisions are made regarding technology selection without proper documentation?

The context and rationale behind those decisions Signup and view all the answers

Which of the following is NOT a component expected to be part of an audit trail?

User Feedback Signup and view all the answers

What does the concept of viewing a network and its environment as a system imply?

Assessing dependencies between users, applications, and devices Signup and view all the answers

In the context of systems methodology, which interface is MOST relevant between users and applications?

User-Application Interface Signup and view all the answers

Which service characteristic is used to describe individual network performance and functionality?

Network Performance Indicators Signup and view all the answers

What relationship does systems methodology focus on within a network's components?

Interactions between components and external entities Signup and view all the answers

Which layer in the OSI model corresponds with the network in systems methodology?

Network Signup and view all the answers

What is a key benefit of spending time on problem definitions during the initial phases of a project?

It saves time and resources later in the project. Signup and view all the answers

Study Notes

Best Effort Performance

Best Effort performance model allows maximum traffic flow but has the downside of potential performance degradation.
When the number of concurrent traffic flows increases, the available capacity decreases.
When the demand for resources exceeds the available capacity, network congestion starts to occur.

Guaranteed Performance

Uses a Call Admission Control (CAC) mechanism.
Maximum number of users/calls allowed until system resources are fully loaded.
No additional users/calls are allowed until resource availability has been restored.

Best Effort vs. Guaranteed

Best Effort is best for networks with fluctuating traffic demands but can suffer from slow responses if the demand is high.
Guaranteed performance is preferable for applications demanding consistent performance but limits the number of users/calls.
A hybrid approach, Predictable Effort, balances both approaches.

Audit Trail Significance

Audit trails allow for tracing decisions and identifying rationale for design choices.
Audit trails should include information about technologies, costs, and time spent.
This documentation can be used to answer questions about the network's design.
Audit trails document requirements, problem definitions, goals, decisions, and data.

Systems Methodology

Network and its environment (e.g. users, applications, devices) should be analyzed as a system.
Traditional network view focuses primarily on the network itself.
A systems methodology takes a broader perspective focusing on interactions and dependencies between the network and its environment.

System Components

User-Application Interface: interacts through displays and user interfaces
Application-Device Interface: communicates through APIs and QoS mechanisms
Device-Network Interface: utilizes device drivers for communication with the network

Comparison to OSI Model

OSI model defines seven layers, while system levels focus on the interaction between users, applications, devices, and the network.
OSI layers are not directly tied to system levels.
System levels emphasize user application and network interactions.

Network Service Characteristics

Service characteristics describe individual network performance and functionality.
Service characteristics act as network requirements. Relevant examples include:
- Providing 1.5 Mb/s peak capacity to a user.
- Guaranteeing a maximum round trip time (RTT) of 100 msec.
- Defining a specific security level for a group of users.

Service Metrics

Service metrics measure specific characteristics within the network to monitor, analyze, and manage services.
Service metrics are necessary for accounting and billing purposes.
Ensure that all network components can support the requested services.

Service Levels

A service level defines a set of service characteristics.
Service levels are offered by service providers to customers as packages with varying features.

Hierarchy of network Levels

The network is organized in hierarchical levels (Access, Core, etc.)
Each level has its own bandwidth and capabilities with specific requirements.

Network Design Sections

Conceptual Model: Defines network requirements, traffic flows, and potential risks.
Logical Model: Outlines relationships within and between network functions (routing, management, etc.)
Physical Model: Defines specific technologies, equipment, and interconnection strategies.

Overview of Network Analysis

Analyzes the current state of the network, any problems present, desired outcomes, and user, application, and device requirements.

Overview of Network Architecture

Defines an end-to-end structure with relationships between network functions and interactions.

Overview of Network Design

Defines the physical details, evaluates and selects technologies, sets interoperability strategies, and outlines evaluation criteria.

Need for Diversity

Diversity improves network performance by connecting networks at different levels.
Diversity provides redundancy in case of failures and distributes traffic flow across the network.

Network Complexity

Network complexity increases with each new generation of network technology.
Each generation represents a level of complexity:
- 1st Generation - Connectivity
- 2nd Generation - Interoperability
- 3rd Generation - Services
- 4th Generation - Decision-making

Defensibility in Network Architecture and Design

Defensibility ensures the decision-making process, including data collection and design choices, is well-documented and justified.
Defensible designs rely on a strong audit trail to support each design choice.

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Description

Explore the fundamental differences between Best Effort and Guaranteed performance models in networking. This quiz covers key concepts such as traffic flow, Call Admission Control, and their implications on network performance. Enhance your understanding of how these models affect user experience and network congestion.