Networking Fundamentals
What a network is
- A network connects devices (nodes) so they can exchange data over links (wired/wireless).
- Data moves using agreed rules (protocols) and identifiers (addresses).
- Common goals: resource sharing, communication, availability, security.
LAN vs WAN vs Internet
- LAN: local area network (home/office); low latency, private addressing common.
- WAN: wide area network (connects LANs across distances); carrier/ISP infrastructure.
- Internet: a global “network of networks” using IP + routing (BGP) to interconnect many WANs.
Client-server model
- Client initiates requests (browser/mobile app); server responds (API, DB, file server).
- Benefits: centralized control, easier updates; Tradeoffs: scaling, single points of failure.
- Variants: multi-tier (client → API → DB), microservices, serverless.
Packet switching vs circuit switching
- Packet switching: data split into packets; each can take different paths; efficient and resilient (Internet).
- Circuit switching: dedicated path reserved for duration of session; predictable latency, less efficient for bursty traffic (classic telephony).
Bandwidth, latency, throughput, jitter
- Bandwidth: theoretical maximum capacity (e.g., 1 Gbps link).
- Latency: time for a unit of data to travel end-to-end (ms).
- Throughput: achieved rate after overheads/loss/congestion (often < bandwidth).
- Jitter: variability in latency; hurts real-time audio/video.