Network Design Lecture 1 PDF

Gathering and Analyzing Requirements Lec1 Dr. Mustafa Al-Sayed Information Flows Between Network Analysis, Architecture, and Design To design a new network or extending an existing one, there are three processes: A- Analysis process...

Gathering and Analyzing Requirements Lec1 Dr. Mustafa Al-Sayed Information Flows Between Network Analysis, Architecture, and Design To design a new network or extending an existing one, there are three processes: A- Analysis process 1- flows; specify the expected traffic flow 2- requirements; user &business requirements 3- risks; expected risks B- Architecture process 1- topology; structure of the needed network 2- relationships between network functions (e.g., privileges, routing, and addressing; what are privileges of each node, and which nodes are locally accessible and which are public) C- Design process 1- what is the needed equipment (switches, routers….) 2- which vendors 3- which location Inputs To and Outputs From the Network Analysis Process Inputs (after listening to users and understanding their needs) what is the current state of the existing network what are the existing problems what are the requirements of users, applications, and devices Outputs: description of problems description of requirements description of risks description of traffic flows specifying/mapping which apps and devices are needed Inputs To and Outputs From the Network Architecture Process Inputs To and Outputs From the Network Design Process Inputs: Network Design process uses information from the Network Architecture Process. Outputs: which vendors for devices which providers for services (services for monitoring network, security, performance…..) which brands for equipment physical drawing of network  Tactical and Strategic Significance Network projects should have a plan that includes current, near-term, and long- term targets, e.g., a one-year/three-year/five-year project plan.  The Cyclic and Iterative Nature of the Three Processes These Tactical and Strategic plans are iterative and should be regularly reviewed, on the order of twice yearly (every 6 months), once per year, or every two years, depending on your plan. Process Iterations Evolve Toward the Long- Term Target At each iteration the current, near-term, and long-term targets are reviewed  Hierarchy and Diversity  All of these processes (analysis, architecture, and design) center around two important characteristics of networks: 1. Hierarchy is the degree of concentration/size/density of networks or traffic flows at interconnection points within the network, as well as, the number of tiers of interconnection points within the network. In sum, Hierarchy provides the structure: o number of nodes: to measure the traffic flow o number of layers: to measure broadcasting 2. Diversity balances this structure by interconnecting the network at different levels in the design to provide greater performance. In sum, Diversity allows redundancy or interconnectivity “connect with each other”: o some links may be repeated to reduce traffic load on a specific point  Hierarchy and Diversity in a Network  This is a tree structure for a network: Circles representing networks or routers Lines representing the communications links between networks and/or routers. Leaves represent the end networks, devices, or users all occur at the same level of hierarchy.  In this figure there are four levels of hierarchy and two levels of diversity.  Hierarchy Added to a Network (from a flat structure to a routed structure)  An example of adding hierarchy to a network is changing from a flat structure to a routed structure.  This may be done to reduce the size of the broadcast domain or the number of devices reached by a broadcast message.  Adding routing to the network breaks a broadcast domain into a number of smaller broadcast domains, and traffic flows are concentrated at routers. Diversity Added to a Network  A content delivery network (CDN) is an example of adding diversity to a network.  A CDN bypasses/avoids the core/inner of a network, where congestion/ overcrowding, and directly connects devices or networks lower in the hierarchy.  This provides better performance but can also affect the network hierarchy by modifying its routing behavior. Understanding Business Goals (1) Meet with Stakeholders: o key stakeholders including executives, department heads, and IT personnel to understand their objectives and the organization vision. Discuss how the network supports current and future goals (e.g., expansion plans, new services, remote workforce support). Identify Business Drivers: o Determine the primary reasons for the network upgrade or redesign (e.g., improve performance, enhance security, support new applications). o Understand the critical applications and services that rely on the network infrastructure. Budget and Resource Constraints: o Gain insights into budget limitations and resource availability for the network project. o Understand any regulatory or compliance requirements that may impact network design decisions. Analyzing Technical Requirements (2) Current Network Assessment: o Including network topology, equipment inventory ‫ﻋﻤ ﻞ ﺟ ﺮﺩ ﻟﻼﺟﻬ ﺰﺓ ﺍﻟﻤﻮﺟ ﻮﺩﺓ‬, and performance metrics (bandwidth utilization, latency, packet loss). o Identify any existing issues or bottlenecks that need to be addressed. Future Growth and Scalability: o Determine the organization’s growth projections/expectations and scalability requirements over the next few years. o Consider factors such as increasing user base, data volume growth, and expansion into new geographic locations. Performance and Reliability: o Define performance metrics (e.g., minimum bandwidth requirements, latency thresholds) that the new network design must meet. o Assess requirements for network availability, redundancy, and failover ‫ ﺗﺠ ﺎﻭﺯ ﺍﻟﻔﺸ ﻞ‬capabilities to ensure business continuity. Assessing User Requirements (3) User Profiles and Needs: o Identify different user groups within the organization (e.g., executives, sales team, IT staff) and their specific network requirements. o Understand the types of devices (desktops, laptops, mobile devices) and applications used by each group. Quality of Service (QoS) Requirements: o Determine if there are specific applications (e.g., VoIP “Voice over Internet Protocol”, video conferencing, ERP systems “enterprise resource planning (ERP) allows you to manage various business aspects, such as company finances”) that require prioritized bandwidth and low latency. o Define QoS policies “prioritize critical traffic”. Security and Compliance: o Gather security requirements related to data protection, access control, and compliances ‫ﺍﻟﺘﺰﺍﻣﺎﺕ‬. o Identify any specific security protocols or technologies (firewalls, VPNs, encryption) that must be implemented. Documentation and Validation (4) Documenting Requirements: o Compile all gathered information into a comprehensive requirements document that outlines business goals, technical requirements, and user needs. o Ensure stakeholders review and approve the document to confirm. Validation and Feedback: o Present the proposed network design and requirements document to stakeholders for validation and feedback. o Incorporate/enter any additional requirements or modifications based on stakeholder input. Network Design Methodologies / Cisco's PPDIOO Network Cycle  PPDIOO stands for Prepare, Plan, Design, Implement, Operate, and Optimize.  PPDIOO is a Cisco network construction methodology that has the following phases: 1. Prepare: based on the current state of the company. If the company has no network, they should develop their business requirements. If there is an existing network, they should update the existing. 2. Plan: also based on the current state of the company If no current network exists, then this project plan should include the allocation of resources (financial/physical) for the design and implementation phases, the development of a network security plan, and the development of a project schedule. If there is an existing network, then the project plan is updated, but only after an audit of the existing infrastructure, sites and operational environment is completed. Network Design Methodologies / Cisco's PPDIOO Network Cycle 3. Design: The company develops (or updates) a comprehensive network design that meets information gathered from the previous two phases. The design will provide a network that is able to manage the everyday tasks that are required of it and meet or exceed all expected availability, reliability, security, scalability, and performance metrics. 4. Implement: It is good to setup and configure a test bed that simulate the different parts of the network design. This method allows the implementers the ability to find any potential problems; If found, these problems are resolved inside this test bed before full scale implementation. Once any issues are solved in the test bed, a full scale implementation can start Once the network has been implemented, a series of tests should be run to ensure that the operation of the new network is as expected and designed. Network Design Methodologies / Cisco's PPDIOO Network Cycle 5. Operate The company is operating without making major changes to the network. During this phase, the company monitors the network performance management, trouble management, security management, and capacity...etc.. 6. Optimize The Optimize phase can happen at any time after a network is operational. If any changes are recommended, then the phases start again from the beginning. Network Traffic Analysis (NTA) Service Requests, Offerings, and Metrics  Service Metrics  For 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.  Thresholds and limits are used to distinguish whether performance is in conformance (adheres to) or nonconformance (exceeds) with a service requirement. Threshold is a value for a performance that is a boundary between two regions of conformance and, when crossed, will generate an action. Limit is a boundary between conforming and nonconforming regions. Crossing a limit is more serious than crossing a threshold, and the resulting action is usually more serious (e.g., dropping of packets to bring performance back to conformance). Performance Limits and Thresholds What is Network Traffic Analysis? Network traffic analysis is the process of monitoring network data to gain insights into how and where network traffic flows. It is important for ensuring: 1. Network availability (risk management) 2. Network performance (identify bottlenecks, optimize resource usage) 3. Network security (detecting security threats such as distributed denial-of-service (DDoS) attacks, malware…etc.) 4. Network Troubleshooting (quickly identify and resolve network issues) 5. Network Capacity Planning (traffic analysis provides insights into current and future usage) Network Traffic Measurement Quantifying the amount and types of data moving across a network at a given time  enables network administrators to: How much network capacity utilization? To understand load on it for planning network resource upgrades to avoid over utilization. Identifying Traffic Patterns: analyze usage patterns to identify peak usage times, popular services or applications...etc. Troubleshooting and Security: quickly identify and resolve anomalies‫ﺷ ﺬﻭﺫ‬, performance issues, or security threats. For example, unusual spikes in traffic could indicate a DDoS attack or other malicious activity. Bandwidth Monitoring, Management, and Fair Usage: identifying high-bandwidth users or applications and implementing appropriate Quality of Service (QoS) policies. Methods and Tools for Network Traffic Measurement Two key methodologies: 1. Volume-based Measurement: quantifies the amount of data transmitted across the network during a specific period.  E.g., SNMP (Simple Network Management Protocol)-based monitoring tool for monitoring traffic volumes and performances of network devices. 2. Flow-based Measurement: network traffic is analyzed based on “flows”, where a flow represents a set of data packets sharing common properties such as source IP, destination IP, and protocol.  E.g., NetFlow, IPFIX, and sFlow tools provide insights into traffic patterns. Methods and Tools for Network Traffic Measurement