Data Communication and Networking
Network Criteria; Network Types — Wired and Wireless; Transmission Media
C-CAT
Network Criteria
Performance
Performance depends on:
- Number of users on the network
- Type of transmission medium (fiber vs copper)
- Capabilities of connected hardware
- Efficiency of the software
Measured in terms of:
- Delay (Latency) — time to transmit data from sender to receiver
- Throughput — effective data rate (bps — bits per second)
Performance Metrics:
| Metric | Formula | Unit |
|---|---|---|
| Bandwidth | Maximum data rate | bps, Mbps, Gbps |
| Throughput | Actual data rate = Bandwidth × Efficiency | bps |
| Latency | Propagation delay + Transmission delay + Processing delay | ms |
| Jitter | Variation in latency | ms |
| Packet Loss | Percentage of lost packets | % |
Reliability
Reliability is measured by:
- Frequency of failure — how often the network goes down
- Time to recover from failure
- Availability / Robustness — percentage of uptime
Availability = (Total Time - Downtime) / Total Time x 100%
Typical enterprise: 99.99% (4 nines) = ~52 minutes downtime/year
Security
Security protects data against:
- Corruption — data altered during transmission
Loss — data dropped or not delivered
- Malicious users — unauthorized access, hacking
Security Goals (CIA Triad):
| Goal | Description |
|---|---|
| Confidentiality | Only authorized users can read the data |
| Integrity | Data is not modified in transit |
| Availability | Network and data are accessible when needed |
Network Types — Wired and Wireless
Wired Networks
Medium: Wire/Cable
Cable Types:
| Cable Type | Speed | Notes |
|---|---|---|
| CAT1 | Voice only | Used only for telephony |
| CAT2 | 1 Mbps | Old token ring networks |
| CAT3 | 10 Mbps | Early Ethernet |
| CAT4 | 16 Mbps | Token ring |
| CAT5 | 100 Mbps | Fast Ethernet |
| CAT5e | 125 Mbps | Enhanced CAT5 |
| CAT6 | 1000 Mbps (1 Gbps) | Gigabit Ethernet |
| CAT7 | 10000 Mbps (10 Gbps) | 10 Gigabit Ethernet |
| CAT8 | 25000 Mbps (25 Gbps) | Data centers |
| Fiber Optic | Minimum 10 Gbps | Data travels as light |
Wired Network Types:
- LAN — Local Area Network
- MAN — Metropolitan Area Network
- WAN — Wide Area Network
Wireless Networks
Medium: Air (Electromagnetic Waves)
Wireless Network Types:
| Type | Full Form | Range | Example |
|---|---|---|---|
| PAN | Personal Area Network | ~10 meters | Bluetooth headset, smartwatch |
| WLAN | Wireless LAN | ~100 meters | Wi-Fi in office/home |
| WAN | Wide Area Network | Nationwide / Global | GSM, 4G, 5G cellular |
Transmission Media
Definition
For any networking to be effective, raw stream of data must be transmitted from one device to another over some medium. Various transmission media can be used for transfer of data.
Types of Transmission Medium
Guided (Wired)
Data travels through a cabling system with a fixed path.
Examples: Copper wires, fiber optic cables
| Medium | Data Form | Speed | Cost | Example |
|---|---|---|---|---|
| Twisted Pair (UTP/STP) | Electrical signal | Up to 10 Gbps | Low | Ethernet cable (RJ-45) |
| Coaxial Cable | Electrical signal | Up to 1 Gbps | Medium | Cable TV, older networks |
| Fiber Optic | Light (photons) | 10 Gbps+ | High | Internet backbone |
Unguided (Wireless)
Data travels through free space as electromagnetic signals.
Examples: Radio waves, lasers, microwaves
| Medium | Frequency | Speed | Range | Example |
|---|---|---|---|---|
| Radio Waves | 3 Hz – 3 GHz | Variable | Long | Wi-Fi, Bluetooth, AM/FM |
| Microwave | 1 GHz – 300 GHz | High | Line of sight | Satellite, microwave tower |
| Infrared | 300 GHz – 400 THz | Moderate | Short | TV remote, IrDA |
| Laser/Light | Optical range | Very high | Short, line of sight | LiDAR, optical communication |
Twisted Pair Cable Details
Maximum length: 100 meters (328 feet) per segment
UTP vs STP:
| Feature | UTP (Unshielded) | STP (Shielded) |
|---|---|---|
| Shielding | No | Yes |
| EMI resistance | Low | High |
| Cost | Lower | Higher |
| Use case | Office LAN | Industrial environments |
How twisted pairs reduce interference:
Wire A (signal) and Wire B (inverse signal) are twisted together.
Electromagnetic interference affects both equally, canceling out noise.
This is called differential signaling.
Coaxial Cable
+--------+--------+--------+--------+
| Inner | Dielec-| Outer | Jacket |
| Cond. | tric | Cond. | |
+--------+--------+--------+--------+
(Copper) (Foil/Braid)
- Inner conductor — carries data signal
- Dielectric — insulates inner from outer conductor
- Outer conductor (shield) — reduces interference
- Jacket — outer protective coating
Types:
- Thinnet (10Base2) — thin, flexible, up to 185 meters
- Thicknet (10Base5) — thick "yellow cable", up to 500 meters
Fiber Optic Cable
Light Source --> Core (glass) --> Cladding --> Buffer --> Jacket
(Laser/LED) (carries light) (reflects light back)
| Feature | Description |
|---|---|
| Signal type | Light (photons) |
| Speed | 10 Gbps to hundreds of Tbps |
| Attenuation | Very low (data travels long distances) |
| EMI immunity | Complete (light is not affected by EMI) |
| Security | High (hard to tap) |
| Cost | Higher than copper |
Types:
- Single-Mode Fiber (SMF) — small core (8-10 microns); laser light; long distance (100+ km); used in WAN, internet backbone
- Multi-Mode Fiber (MMF) — larger core (50-62.5 microns); LED light; shorter distance (<2 km); used in LAN, data centers
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