Overview
This lecture covers the importance of choosing the correct cabling for networking, different types of network cables, ethernet standards, and special requirements for cable installation in building plenums.
Importance of Cabling in Networking
- Cabling is essential for all networking devices, including routers, switches, and wireless access points.
- Once installed, cabling is difficult to replace, so choosing the right type is critical.
- Even wireless networks eventually connect to cables for infrastructure purposes.
Types of Network Cables
- Twisted pair copper cable is the standard for most wired ethernet connections.
- Wires in twisted pairs carry balanced signals (transmit+/transmit−, receive+/receive−) to reduce interference.
- Pairs in twisted cables have different twist rates for further protection against interference.
- Coaxial cable (coax) is another common ethernet cable, featuring a single conductor, insulator, shielding, and jacket.
- RG6 is a common coaxial cable for cable modem and internet connections.
- Twinaxial (twinax) cable has two conductors and is used for high-speed (10 Gbps) ethernet, often with SFP+ interfaces.
Ethernet Standards and Cable Categories
- The ethernet standard (IEEE 802.3) dictates the required minimum cable type and supported throughput.
- Cable categories (Cat 5, Cat 6, Cat 7) define quality and performance; higher categories support higher speeds.
- Example: 1000BASE-T ethernet requires at least Category 5 cable for proper function.
Plenum Spaces and Cable Ratings
- Plenum refers to shared airspace above drop ceilings where cables are often installed.
- Using non-plenum rated cables in plenums is a fire safety risk due to smoke and hazardous fume production.
- Plenum rated cables use materials (fluorinated ethylene polymer or low-smoke PVC) that are safer in fires.
- Plenum rated cables are less flexible, making installation more challenging around bends.
Key Terms & Definitions
- Twisted Pair Cable — A cable with pairs of wires twisted together to minimize interference.
- Coaxial Cable — A cable with a central conductor, insulator, shielding, and jacket sharing a common axis.
- Twinax Cable — A cable with two conductors, commonly used for 10 Gbps ethernet.
- Plenum — A shared airspace between the drop ceiling and the actual ceiling used for cable runs.
- Plenum Rated Cable — Cable designed with fire-resistant materials for use in plenum spaces.
- Category (Cat) Cable — A classification specifying the performance of twisted pair cabling.
Action Items / Next Steps
- Review the IEEE 802.3 standard for correct ethernet cabling requirements.
- Check building cable routes to ensure use of proper plenum or non-plenum cables as required.