Computer Network Components

Network Basics

• Enables data transfer among nodes
• Comprises heterogeneous nodes, more than two nodes
• End Systems: sinks or source of data, examples include Desktop, Laptop, Servers, Printers, Cellphones, etc.
• Intermediate System: forward/switch data from one link to another, examples include Routers, switches

Host and Clients

• Host: End Systems that provide service, examples include Print Server, Storage Server, Mail Server, etc.
• Clients: End Systems that request service

Links and Internet

• Links: connect systems, characterized by transmission rate, propagation delay
• Internet: Inter-Network, connecting multiple networks
• Approximately 1.5 billion hosts on Internet in 2016
• Internet Service Provider (ISP): provides access to Internet, examples include Telecommunication (Telephone) Companies, Coffee Shops (Wi-Fi)

Network Types

• Local Area Network (LAN): 0-2km, single ownership
• Metropolitan Area Network (MAN): 2-50 km
• Wide Area Network (WAN): 50+ km

ISP and Access

• Types of ISPs: Tier 1 (Global or National), Tier 2 (Regional), Tier 3 (Local)
• Access: between subscriber and service provider, divided into Metro (covering the city), Core (between cities)

Transmission Media

• Guided: Twisted Pair, Coaxial Cable, Optical Fiber
• Unguided: Microwave, Satellite, Wireless

UTP Categories

• CAT 3: up to 16Mhz, voice grade, twist length of 7.5cm to 10cm
• CAT 4: up to 20Mhz, not used much in practice
• CAT 5: up to 100Mhz, used in 10Mbps and 100Mbps Ethernet, twist length of 0.6cm to 0.85cm
• CAT 5e (Enhanced), Cat6, Cat7...

Network Edge

• Enterprise Network: Ethernet, Wi-Fi
• Ethernet: uses UTP, 10Mbps, 100Mbps, 1 Gbps, 10Gbps, originally bus, now point-to-point (Star) topology
• Wi-Fi: IEEE 802.11, uses 2.4Ghz and 5.8Ghz

Access Networks

• 1. DSL (Digital Subscriber Line)
• 2. Cable
• 3. Fiber-To-The-Home (FTTH)
• 4. Wi-Fi (Wireless Fidelity)
• 5. LTE (Long Term Evolution)