Session 1 – Introduction to Network Design

Design of Computer Networks (MTDATNT)

Prof Justin Pineda CISSP, CISM

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Motivation / Ice-Breaker

1. How many networks did you use today before arriving here?
2. Mobile network
3. Office or home Wi-Fi
4. Cloud applications
5. Banking or messaging platforms
6. Network design is the invisible infrastructure behind modern life.

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Insert image: people using phones, laptops, cloud apps, and connected services

Why Network Design Matters

1. Poor network design can lead to outages, slow performance, and security exposure.
2. A well-designed network supports business continuity, growth, and user experience.
3. Network design is both a technical and strategic business concern.

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Insert image: enterprise outage dashboard / failed services / NOC screen

Learning Objectives

1. Explain the evolution of computer networks.
2. Differentiate LAN, WAN, and global networks.
3. Discuss core network design principles.
4. Understand topology fundamentals.
5. Compare enterprise and carrier networks.
6. Prepare for a semester-long research topic on a network environment.

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What is Network Design?

1. Network design is the structured planning of connectivity, devices, flows, and controls.
2. It considers architecture, scalability, reliability, security, performance, and cost.
3. Good design aligns technical infrastructure with organizational requirements.

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Insert image: network blueprint / architect reviewing topology diagram

Evolution of Computer Networks

1. Computer networks evolved from isolated systems into globally interconnected platforms.
2. The progression includes academic, government, enterprise, commercial, mobile, and cloud-driven stages.
3. Each stage introduced new design challenges and new models of communication.

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Insert image: timeline of networking history / vintage computer to cloud

Early Networks: ARPANET and Packet Switching

1. Early networking efforts focused on resilient communication among research institutions.
2. Packet switching became a foundational concept for modern networking.
3. ARPANET demonstrated that distributed communication could scale beyond a single location.

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Insert image: ARPANET map / early computing lab / packet switching concept

The Internet as a Network of Networks

1. The Internet connects independent networks using common protocols.
2. TCP/IP enabled diverse systems to interoperate at scale.
3. This model allowed global interconnection across organizations and countries.

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Insert image: world map with interconnected networks / internet backbone

From Centralized Computing to Distributed Connectivity

1. Networking evolved from centralized mainframes to client-server, distributed, cloud, and edge models.
2. Modern environments combine local, regional, and global communication patterns.
3. Design today must account for users, workloads, and data that are geographically dispersed.

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Local Area Networks (LAN)

1. A LAN covers a relatively small geographic area such as an office, building, or campus floor.
2. LANs typically provide high bandwidth and low latency.
3. They are usually privately managed by the organization using them.

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Insert image: office floor network / switches and workstations

Typical LAN Components

1. Common LAN components include switches, wireless access points, routers, firewalls, and endpoints.
2. LAN design often focuses on segmentation, manageability, speed, and user access.
3. The LAN is where most users directly experience the network.

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Insert image: enterprise LAN diagram / office switch and access point layout

Wide Area Networks (WAN)

1. A WAN connects multiple LANs over larger geographic distances.
2. It is commonly used to connect branch offices, data centers, remote sites, and cloud environments.
3. WAN performance is shaped by latency, provider services, and link resilience.

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Common WAN Technologies

1. Examples include MPLS, SD-WAN, leased lines, microwave, satellite, and fiber connectivity.
2. Organizations choose WAN technologies based on cost, performance, resilience, and control.
3. Modern WAN design increasingly emphasizes flexibility and application-aware routing.

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Insert image: SD-WAN dashboard / MPLS cloud / telecom backbone

Global Networks

1. Global networks operate across countries and continents.
2. Examples include cloud provider backbones, content delivery networks, and the public Internet.
3. These networks must manage scale, redundancy, and international reach.

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Insert image: global submarine cable map / hyperscale backbone

LAN vs WAN vs Global Networks

1. LAN: local scope, high speed, low latency, organization-managed.
2. WAN: regional or national scope, connects multiple LANs, often provider-assisted.
3. Global: international scope, massive scale, backbone-oriented and highly redundant.

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Insert image: three-level comparison diagram for LAN WAN global

Core Network Design Principles

1. Strong network design balances scalability, reliability, performance, security, manageability, and cost.
2. No design decision exists in isolation; trade-offs are unavoidable.
3. The role of the designer is to optimize for business and operational needs.

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Scalability

1. A scalable network can support growth in users, devices, applications, and traffic volume.
2. Designers must anticipate future demand instead of building only for current needs.
3. Scalability reduces the need for disruptive redesign later.

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Reliability and Resilience

1. Reliable networks continue operating even when individual components fail.
2. Resilience is supported by redundancy, failover, backup paths, and fault-tolerant design.
3. This is especially important for banking, healthcare, telecom, and critical services.

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Insert image: redundant links / failover diagram / resilient network

Performance

1. Performance includes throughput, latency, jitter, and application responsiveness.
2. Design choices influence user experience and service quality.
3. Performance engineering is essential for real-time and transaction-heavy environments.

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Insert image: network performance charts / speed dashboard

Security by Design

1. Security should be integrated into architecture, not added later as an afterthought.
2. Segmentation, access control, monitoring, and secure connectivity reduce risk exposure.
3. A poorly designed network can magnify the blast radius of an incident.

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Insert image: segmented network / firewall and security layers

Manageability and Operational Simplicity

1. Networks should be designed so they can be monitored, maintained, and troubleshot efficiently.
2. Operational complexity increases cost and risk.
3. A design that is elegant on paper but difficult to operate often fails in practice.

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Insert image: NOC operators / monitoring dashboard / manageable architecture

Topology Fundamentals

1. Topology describes how devices and links are arranged and interconnected.
2. It can be physical, logical, or both.
3. Topology influences reliability, cost, performance, and troubleshooting.

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Star Topology

1. In a star topology, endpoints connect to a central device such as a switch.
2. This model is common in modern Ethernet networks.
3. It is easy to manage, but the central device can become a single point of failure if not protected.

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Insert image: star topology diagram

Mesh Topology

1. In a mesh topology, devices or sites have multiple interconnections.
2. Mesh designs offer redundancy and alternate paths.
3. They are common in carrier backbones and high-availability environments.

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Insert image: mesh topology diagram / interconnected nodes

Ring, Bus, and Hybrid Topologies

1. Ring and bus topologies are historically significant but less common in modern enterprise environments.
2. Hybrid topologies combine multiple models to meet practical requirements.
3. Most real-world networks are hybrid rather than purely one topology type.

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Enterprise Networks

1. Enterprise networks support internal business operations, users, systems, and applications.
2. Examples include banks, schools, hospitals, manufacturing firms, and government offices.
3. Design priorities often include security, segmentation, application performance, and governance.

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Insert image: corporate office network / enterprise campus network

Carrier Networks

1. Carrier networks are operated by telecom and service providers.
2. Their purpose is to deliver connectivity services at scale.
3. They prioritize backbone capacity, service availability, routing efficiency, and coverage.

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Enterprise vs Carrier Networks

1. Enterprise networks are designed to support organizational operations and applications.
2. Carrier networks are designed to deliver network services to many customers.
3. The scale, ownership, priorities, and operational models are fundamentally different.

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Insert image: side-by-side enterprise vs carrier comparison diagram

Example: Banking Network Environment

1. A banking environment may include branches, ATMs, mobile apps, online banking, and data centers.
2. The network must support confidentiality, availability, resilience, and transaction integrity.
3. Design mistakes in such environments have both technical and business consequences.

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Example: Cloud Provider Network Environment

1. Cloud providers operate global backbones, regional data centers, and edge points of presence.
2. Design must support immense scale, automation, and geographic diversity.
3. This is a useful research environment for students interested in hyperscale infrastructure.

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Insert image: cloud regions and edge network map

Research Orientation for the Course

1. Students will progressively analyze a chosen network environment throughout the semester.
2. The research topic should be concrete enough to study and broad enough to sustain analysis.
3. This creates a bridge between lecture content and applied graduate-level inquiry.

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Summary

1. Computer networks evolved into critical infrastructure that underpins modern society.
2. LAN, WAN, and global networks differ in scale, purpose, and design considerations.
3. Good network design is guided by principles such as scalability, reliability, performance, and security.
4. Enterprise and carrier networks require different architectural perspectives.

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Knowledge Check

1. What is the key difference between LAN, WAN, and global networks?
2. Why is scalability important in network design?
3. How does topology affect resilience and manageability?
4. What distinguishes enterprise networks from carrier networks?

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For Session 2: Student Presentation Day

Learning Objectives

• By the end of the session, students will be able to:
• Explain the structure of enterprise network architecture
• Describe the evolution of Ethernet technologies
• Understand how Internet architecture enables global connectivity
• Analyze design tradeoffs between enterprise and Internet-scale networks
• Apply basic research methods in technical network analysis

Enterprise Network Architecture

Three-tier enterprise network model (Core / Distribution / Access)

Campus network architecture

Network segmentation and VLAN design

Enterprise data center networks

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Ethernet Evolution

From 10 Mbps Ethernet to Gigabit Ethernet

Fast Ethernet, Gigabit Ethernet, and 10/40/100 Gb Ethernet

Ethernet switching and Layer 2 networks

IEEE 802.3 Ethernet standards

Internet Architecture

Internet backbone infrastructure

Autonomous Systems and BGP

Internet Exchange Points (IXPs)

Content Delivery Networks (CDNs)

Submarine cable systems

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Network Design Perspectives

Enterprise network design principles

Internet-scale architecture

Hyperscale cloud networks

Enterprise vs Internet-scale tradeoffs

For Session 2: Student Presentation Day

Presentation Length

5–7 minutes per student/group

5–6 slides recommended

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Suggested Structure

Introduction to the topic

Key technical concepts

Architecture or network diagram

Real-world example

Design considerations or tradeoffs

Presentation Guidelines