Лист за преговор: Fundamentals of Computer Networking

📋 Course Outline

1. Network media: wired and wireless types
2. Ethernet cabling: standards, abbreviations and limits
3. Copper data cable structure and CAT categories
4. Network topologies: availability, security and tradeoffs
5. Structured cabling: ISO/IEC levels and building components
6. Computer networks: definition, services and scope

📖 1. Network media: wired and wireless types

🔑 Key Concepts & Definitions

• Twisted-Pair Leitung : A wired network medium that uses multiple twisted copper wire pairs to carry electrical signals.
• Lichtwellenleiter : A wired network medium that transports data as light through fiber, carrying optical signals.
• WLAN / WiFi : A wireless network medium that transmits data over radio waves using WiFi standards.

📝 Essential Points

• Wired media carry electrical signals on copper (e.g., twisted-pair, coax) or optical signals in fiber (multimode or single-mode).
• Wireless media include radio links such as WLAN/WiFi and point-to-point radio (Richtfunk) for data transmission through the air.
• Fiber installation is typically more complex but offers strong interference resistance and very good transmission properties.

💡 Memory Hook

Copper = electricity; Fiber = light; WiFi = radio through the air.

📖 2. Ethernet cabling: standards, abbreviations and limits

🔑 Key Concepts & Definitions

• Permanent Link : A cabling segment measured as fixed installation, with a maximum length limit for the structured cabling part.
• Channel Link : A complete end-to-end cabling path that includes the fixed cabling plus patch leads, with a larger maximum length than the Permanent Link.
• UTP : An Ethernet cable type using twisted pairs without shielding, typically abbreviated as UTP in cabling standards.

📝 Essential Points

• Copper Ethernet distance depends on link speed, with typical limits of 100 m for 100 Mbit/s and 1 Gbit/s and up to about 2000 m to 550 m for 10 Gbit/s depending on the medium/standard.
• Structured cabling uses fixed cabling (Permanent Link max 90 m) plus patch cables (2×5 m) to form a Channel Link max 100 m.
• A cable break or faulty T-branch can act as a single point of failure and disrupt an entire segment, especially in line topologies.

💡 Memory Hook

Permanent Link = fixed part (≤90 m); Channel Link = fixed + patches (≤100 m).

📖 3. Copper data cable structure and CAT categories

🔑 Key Concepts & Definitions

• Copper data cable : A copper-based network cable that carries Ethernet signals over twisted copper conductors.
• CAT category : A cable rating (e.g., CAT5e, CAT6, CAT7) that specifies performance limits such as bandwidth and signal quality.

📖 4. Network topologies: availability, security and tradeoffs

🔑 Key Concepts & Definitions

• Star topology : A network layout where many connections converge on a central switch or core device.
• Ring topology : A network layout where links form a closed loop and communication depends on ring operation.

📝 Essential Points

• Star topology has a single point of failure at the central switch/core, harming availability.
• Ring-based designs can be harder to scale and troubleshoot because failures require understanding ring behavior.
• Wireless links add interference risk and eavesdropping exposure; if an access point fails, its cell can go silent.

💡 Memory Hook

Star = “one hub breaks all”; Ring = “loop dependency”; Wireless = “airwaves risk + cell outage”.

📖 5. Structured cabling: ISO/IEC levels and building components

🔑 Key Concepts & Definitions

• Primary cabling : Structured cabling segment that connects the building’s main distribution area to lower distribution points.
• Secondary cabling : Structured cabling segment that runs from the floor distribution area to the local network outlets.
• Tertiary cabling : Structured cabling segment that links the distribution patching to the end devices’ network ports.

📝 Essential Points

• Floor distributor (EV) and building distributor (GV) are building components used to organize cabling levels.
• Network outlets (KA/TA) connect to end devices via copper LAN cables or fiber patching.
• Fiber options include multimode fiber for secondary cabling and single-mode fiber patch cables for fiber patching.

💡 Memory Hook

Primary→EV/GV, Secondary→SV/EV patching, Tertiary→KA/TA outlets to end devices.

📖 6. Computer networks: definition, services and scope

🔑 Key Concepts & Definitions

• Computer network : A computer network is a set of connections between independent computers of different types that enables data exchange among devices.
• Internet : The Internet is a worldwide public network that provides services for everyone.
• Intranet : An intranet is a private closed network used within an organization.

📝 Essential Points

• Networks enable centralized data storage and easier access, plus shared resources like storage, printers, and web servers.
• Common network services include DNS name resolution, DHCP for IP address assignment, and data services such as file transfer, e-mail/chat, video conferencing, online gaming, and e-commerce.
• Scope by access and reach includes Internet (public), intranet (private), and extranet (intranet accessible to external partners).

💡 Memory Hook

Scope ladder: Internet (public) → Intranet (private) → Extranet (private + external access).

📊 Synthesis Tables

Network media: wired vs wireless

Type	Examples (from source)	Signals / medium
Wired	Twisted-Pair-Leitung, Koaxial-Leitung, Lichtwellenleiter	Electrical signals on copper; optical signals in Lichtwellenleitern
Wireless	WLAN / WiFi, Richtfunk, Funkübertragung, Laserlink	Data transmission through the air (radio / optical through air)

Network topologies: availability & security tradeoffs

Topology	Availability / failure behavior	Security aspect
Star / extended star	Central switch is a Single Point of Failure; redundancy needs stack/core-switched designs	Central point is attractive for attacks; compromised core switches endanger the LAN
Ring	Classic rings fail when the logical path is interrupted; modern industrial ring protocols can switch quickly for high availability	Shared medium concept exists; with ring, passive listening is harder due to multiple paths, but more attack/manipulation points exist
Wireless cells	AP failure makes its Funkzelle silent; neighboring cells can continue	Eavesdropping risk is high; strong encryption and authentication are required

⚠️ Common Pitfalls & Confusions

1. Mixing up wired vs wireless: WLAN/WiFi and Richtfunk are non-leitungsgebunden, while Twisted-Pair/Koax and fiber are leitungsgebunden.
2. Confusing Permanent Link with Channel Link: Permanent Link is only the fixed cabling (max 90 m), while Channel Link includes patch leads (max 100 m).
3. Assuming one cable fault only affects one device: a cable break or faulty T-branch can disrupt an entire segment, especially in line topologies.
4. Thinking fiber is “easy” like copper: the source states Lichtwellenleiter require higher installation effort but give strong interference resistance and very good transmission properties.
5. Mixing up structured cabling levels: Primary/Secondary/Tertiary correspond to SV/GV/EV and KA/TA, not to arbitrary “random” patch points.
6. Forgetting that star has a central Single Point of Failure: availability drops when the central switch/core fails unless redundancy is designed.
7. Confusing Internet vs Intranet vs Extranet: Extranet is the intranet accessible to external partners, not a fully public network like the Internet.

✅ Exam Checklist

1. Complete the network media classification: fill the diagram with leitungsgebunden vs nicht leitungsgebunden and the correct signal types (electrical on copper, optical in fiber, transmission through air).
2. List the three important network media for data transmission and distinguish their examples: Twisted-Pair/Koax/fiber vs WLAN/WiFi/Richtfunk/Laserlink.
3. For Ethernet cabling abbreviations (IEEE 802.3), state the common name, maximum data rate C, and maximum medium length for each listed variant (100Base-T, 1000Base-T/1GBase-T, 10GBase-T, 100Base-FX, 1000Base-SX, 10GBase-
4. Explain why fiber installation has higher effort but better transmission properties and higher interference resistance than copper (as stated in the source).
5. Describe the structure of copper data cables using CAT logic: the cable construction determines the CAT category, which determines maximum transmission frequency/bandwidth and thus possible data rate.
6. Given the four data lines (Cu/LWL with 100 Mbit/s, 1000/1 Gbit/s, 10 Gbit/s), identify which medium is used and the corresponding maximum distances from the provided values.
7. Connect max copper distances to Permanent Link vs Channel Link: Permanent Link max 90 m plus patch cables (2×5 m) equals Channel Link max 100 m.
8. Know the structured cabling definition and benefits: an application-independent, passive, hierarchical building cabling that is future-oriented and supports today’s and future communication systems.
9. Explain why structured cabling can be called UGV (“Dienstunabhängigkeit”): it supports different transmission services (data, telephone, TV) in a common cable structure.
10. Name the ISO/IEC 11801 levels and the corresponding distributor points: Primary cabling (SV/GV), Secondary cabling (GV/EV), Tertiary cabling (EV/KA/TA).
11. Match building plan objects to structured cabling areas: TA/KA, EV, GV, SV, and the correct cabling/patch elements (e.g., MultiMode fiber for secondary cabling, Single Mode fiber patch cables, patch panels for copper and
12. Master computer networks basics: define a computer network, list at least three advantages, and list network services in a local network and in the Internet (including DNS, DHCP, file transfer, e-mail/chat, video, online
13. Explain Internet vs Intranet vs Extranet and the difference between classic analog telephone network and the Internet (digital, packet switching, data in packets).
14. Classify network scope by size and public/private: know the abbreviations WAN, MAN, LAN, PAN, GAN and sort them from small to large using the provided statements.