Cp7101 design and management of computer networks -network
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This document discusses network analysis, architecture, and design. It covers: 1) The importance of network analysis in defining problems and requirements before establishing network architecture and design. 2) How network architecture uses the information from analysis to develop a high-level structure and make technology and topology choices. 3) How network design provides physical detail to the architecture by selecting locations, equipment, and vendors.
Cp7101 design and management of computer networks -network
- 1. CP7101-Design and Management of Computer Networks Dr.G.Geetha Professor /CSE Jerusalem College of Engineering
- 2. Design of A Network • Logical • Reproducible • Defensible
- 3. Network Design Objective • Our network design must answer some pretty basic questions – What stuff do we get for the network? – How do we connect it all? – How do we have to configure it to work right? • Traditionally this meant mostly capacity planning – having enough bandwidth to keep data moving – May be effective, but result in over engineering
- 4. Focus • Capacity Capacity is the complex measurement of the maximum amount of data that may be transferred between network locations over a link or network path. • Bandwidth Bandwidth is often used as a synonym for data transfer rate - the amount of data that can be carried from one point to another in a given time period (usually a second). This kind of bandwidth is usually expressed in bits (of data) per second (bps).
- 5. Network -RMA • Reliability • Probability that an engineering system will perform its intended function satisfactorily (from the viewpoint of the customer) for its intended life under specified environmental and operating conditions • Maintainability • Probability that maintenance of the system will retain the system in, or restore it to, a specified condition within a given time period • A measure of the ease and rapidity with which a system or equipment can be restored to operational status following a failure • Availability • Availability is the probability that the system is operating satisfactorily at any time, and it depends on the reliability and the maintainability • Availability of end to end functionality for customers. • Ability to experience failures or systematic attacks, without impacting customers or operations
- 6. Logical Sessions Designing a network into three sections: • Analysis process • How to develop requirements, understand traffic flows, and conduct a risk analysis • Network architecture • How to make technology and topology choices for your network, • How to understand the relationships among the various functions within your network, • How to use this information to develop an architecture • Design process • Where location information, equipment, and vendor selections are used to detail the design
- 7. Network analysis • Network analysis defines, determines, and describes relationships between network components for many conditions. • The purpose of network analysis • first, to listen to users and understand their needs; • second, to understand the system.
- 8. Network analysis • Entails learning what users, their applications, and devices need from the network • Also about understanding network behavior under various situations • Also defines, determines, and describes relationships among users, applications, devices, and networks. In the process, • Network analysis provides the foundation for all the architecture and design decisions to follow.
- 9. Network architecture • Uses this information to develop a high-level, end-to-end structure for the network. • Develops the major network functions (e.g., addressing/routing, network management, performance, security) as architectural components that will be brought together to form the network • Finding the best network
- 10. Network architecture • Process determines sets of technology and topology choices; • Classes of equipment needed • Relationships among network functions • addressing/routing, network management, performance, and security
- 11. Network design • Provides physical detail to the reference architecture • Design goals such as minimizing network costs or maximizing performance,
- 12. Network design • Network design provides physical detail to the architecture. • It is the target of our work, the culmination of analysis and architecture processes. • Physical detail includes • blueprints and drawings of the network; • selections of vendors and service providers • selections of equipment (including equipment types and configurations)
- 13. Two Main Principles • For a network design to work well, we need to balance between – Hierarchy – how much network traffic flows connect in tiers of organization • Like tiers on an org chart, hierarchy provides separation and structure for the network – Interconnectivity – offsets hierarchy by allowing connections between levels of the design, often to improve performance between them
- 15. Hierarchy • Degree of concentration of networks or traffic flows at interconnection points within the network • Number of tiers of interconnection points within the network • help us in • Determining the sizes of networks, • Routing and addressing configurations, • Scaling of network technologies, • Performance, and service levels
- 16. Hierarchy (cont…) • Provides a separation of the network into segments. • Segments may be separate, smaller networks (subnets) or broadcast domains. • Necessary • when the amount of traffic on the network grows beyond the capacity of the network • when interactions between devices on the network result in congestion (e.g., broadcast storms).
- 17. Diversity • Interconnectivity or redundancy • As hierarchy provides structure in the network, interconnectivity balances this structure by interconnecting the network at different levels in the design to provide greater performance through parts of the network. • Provides a mechanism to achieve performance within a hierarchical structure.
- 18. Importance of Network Analysis • Network requirements are requests for capabilities in the network, • performance and function, which are necessary for the success of that network.
- 19. Network and System Complexity • Complexity lies in the sophistication of the capabilities provided by that network. • Quality of service • Refers to determining, setting, and acting on priority levels for traffic flows • Service-level agreement • Policies
- 20. service-level agreement • Informal or formal contract between a provider and user that defines the terms of the provider’s responsibility to the user and the type and extent of accountability if those responsibilities are not met
- 21. Policies • High-level statements about how network resources are to be allocated among users
- 22. Network analysis, architecture, and design • Defining the problems to be addressed • Establishing and managing customer expectations • Monitoring the existing network, system, and its environment • Analyzing data • Developing a set of options to solve problems • Evaluating and optimizing options based on various trade-off • Selecting one or more options • Planning the implementation
- 23. Systems Methodology • means viewing the network along with a subset of its environment (everything that the network interacts with or impacts), as a system. • concepts of the systems methodology • Network architectures and designs take into account the services that each network will provide and support
- 24. System Description • a set of components that work together to support or provide connectivity, communications, and services to users of the system
- 25. Service Description • levels of performance and function in the network. • network services as sets of network capabilities that can be configured and managed within the network and between networks. We apply this concept to network analysis, architecture, and design, integrating services throughout the entire system
- 26. two perspectives • Services being offered by the network to the rest of the system (the devices, applications, and users) • as sets of requirements from the network that are expected by the users, applications, or devices.
- 27. • Performance characteristics • Capacity, delay, and RMA • Functions • security, accounting, billing, scheduling, and management (and others)
- 28. Service Characteristics • Service Levels • System Components and Network Services • Service Requests and Requirements • Service Offerings • Service Metrics
- 29. Service Characteristics • Individual network performance and functional parameters that are used to describe services. • service offering • offered by the network to the system • Service request • requested from the network by users, applications, or devices (the).
- 30. service metrics • Measurements of these characteristics in the network to monitor, verify, and manage services are called service metrics.
- 31. Requirements based on • capacity • delay • RMA requirements • per user • application • and/or device • along with requirements for security, manageability, • usability • flexibility • others.
- 32. Service Levels • Service characteristics can be grouped together to form one or more service levels for the network. • done to make service provisioning easier in that you can configure, manage, account, and bill for a group of service characteristics (service level) instead of a number of individual characteristic
- 33. Describe service levels • Frame relay committed information rates (cirs), which are levels of capacity • Classes of service (coss),which combine delay and capacity characteristics • IP types of service (toss) • Qualities of service (qoss), which prioritize traffic for traffic conditioning functions
- 34. System Components and Network Services • Network services are derived from requirements at each of the components in the system. • They are end-to-end within the system, describing what is expected at each component
- 35. Service requirements • Derived from each component • User requirements • Application requirements • Device requirements • (existing) network requirements
- 36. Service Requests and Requirements • the degree of predictability needed from the service by the user, application, or device making the request • categorized as • best effort, • predictable, • guaranteed • Best-effort service means that there is no control over how the network will satisfy the service request • there are no guarantees associated with this service.
- 37. Service Requests • Guaranteed service is the opposite of best-effort service • best-effort service is unpredictable and unreliable • guaranteed service must be predictable and reliable • With best-effort and guaranteed services at opposite ends of the service spectrum, many services fall somewhere between. These are predictable services, which require some degree of predictability (more than best effort) yet do not require the accountability of a guaranteed service.
- 38. Service Requests • Best-effort, predictable, and guaranteed service refer to the degree of predictability of a request or requirement, whereas low and high performances refer to a relative performance level for that request or requirement
- 39. Service Offerings • the network counterparts to user, application, and device requests for service. • Service requests that are generated by users, applications, or devices are supported by services offered by the network • categorized as • Best effort, • predictable • guaranteed
- 40. Service Metrics • service performance requirements and characteristics to be useful, they must be configurable, measurable, and verifiable within the system. • service metrics are meant to be measurable quantities, they can be used to measure thresholds and limits of service.
- 41. Thresholds and Limits • A threshold is a value for a performance characteristic that is a boundary between two regions of conformance and, when crossed in one or both directions, will generate an action. • A limit is a boundary between conforming and nonconforming regions and is taken as an upper or lower limit for a performance characteristic
- 42. Performance Characteristics • Capacity Capacity is a measure of the system’s ability to transfer information • Delay Delay is a measure of the time difference in the transmission of information across the system • RMA • Performance Envelopes A performance envelope is a combination of two or more performance requirements, with thresholds and upper and/or lower limits for each
- 43. RMA • Reliability is a statistical indicator of the frequency of failure of the network and its components and represents the unscheduled outages of service • Maintainability is a statistical measure of the time to restore the system to fully operational status after it has experienced a fault. • Availability (also known as operational availability) is the relationship between the frequency of mission- critical failures and the time to restore service.
- 44. Availability • A=(MTBF)/(MTBF+MTTR) • mean-time-to-repair (MTTR) • mean time between failures A=(MTBCF)/(MTBCF+MTTR) mean time between mission-critical failures
- 45. Network Supportability • The ability of the customer to sustain the required level of performance over the entire life cycle of the network is an area of networking that is often neglected. • It is a mistake to assume that a successful network architecture and design meet the requirements only on the day it is delivered to the customer and that future requirements are the responsibility of the customer.
- 46. Network’s life cycle • phases of a network’s life cycle can be broken into three elements: • Operations, • Maintenance, • Human knowledge.
- 47. Network’s life cycle • operations element focuses • on ensuring that the network and system are properly operated and managed and that any required maintenance actions are identified • Maintenance element focuses • on preventive and corrective maintenance and the parts, tools, plans, and procedures for accomplishing these functions
- 48. Network’s life cycle • Human knowledge element is the set of documentation, training, and skilled personnel required to operate and maintain the network and system
- 49. Key characteristics of a network architecture and design that affect the post implementation costs include: • Network and system reliability • Network and system maintainability • Training of the operators to stay within operational constraints • Quality of the staff required to perform maintenance actions
- 50. key network architecture/design decisions that affect these characteristics include: • Degree of diversity of critical-path components in network architecture/design • Quality of network components selected for installation • Location and accessibility of components requiring frequent maintenance • Implementation of built-in test equipment and monitoring techniques
- 51. Supportability • two major tasks must be accomplished to ensure supportability: 1. Conformance to the network architecture and design must be validated and nonconformance corrected or (at least) documented to ensure that performance is adequate and that maintenance can be performed. 2. Operations and maintenance personnel must understand and be trained in the technologies that are being deployed, including how to operate the network and system properly, when to perform maintenance, and how to most quickly restore service in the event of a fault.
- 52. • Overview of Analysis, Architecture, and Design Processes • Process Components • Tactical and Strategic Significance • Hierarchy and Diversity • Importance of Network Analysis • Model for Network Analysis, Architecture, and Design • A Systems Methodology • System Description • Service Description • Service Characteristics • Service Levels • System Components and Network Services • Service Requests and Requirements • Service Offerings • Service Metrics • Performance Characteristics • Capacity • Delay • RMA • Performance Envelopes • Network Supportability