PHYSICAL NETWORKING
- Introduction to Networking
- LAN computers connect with Ethernet. (Local Area Network)
- Ethernet frames standardized as 1500 bytes
- A MAC address uniquely identifies a host on a LAN. (MAC-Media Access Control; a MAC is a 48-bit address; always manifested as 12 hexadecimal characters)
- Use ‘ipconfig’ (Windows) or ‘ifconfig’ (Linux) to view MAC.
- Example MAC address: xx-xx-xx-xx-xx-xx (the first 3 sets of pairs combined together are known as the OEM ID.
- Hubs vs. Switches
- Hubs repeat all traffic on LAN to all nodes (Hub = ‘dumb’ repeater)
- Switches filter traffic based on MAC address (Switch = smart repeater)
- Switches provide full bandwidth for all nodes
- Hexadecimal
- Hexadecimal (base 16) enables discussion of long strings of 1’s and 0’s.
- Each hex character represents 4 binary numbers (0000-1111)
- In hex, numbering goes 0-9, a-f, for 0-15.
- WAN & Routers
- Switches connect (up to 1024) computers in LAN.
- Routers connect multiple LANs together in WAN (Wide Area Network)
- Routers use logical addressing (IP addressing) to determine local vs. remote traffic.
- Cabling
- WANs & Routers
- Coaxial cables use RG ratings and F-type connectors
- Most networks use twisted pair cabling
- Fiber optic cables use light, rather than electrical pulses.
- Twisted pair cabling have different category (CAT) ratings. (Know these ratings and speeds!)
- STP vs UTP (Shielded Twisted Pair vs. Unshielded Twisted Pair)
- CAT ratings (category ratings)
- CAT 5–100 Mbps
- Cat 5e—1 Gbps
- Cat 6–1 Gbps up to 100 meters or 10 Gbps up to 55 meters
- Cat 6a—10 Gbps at 100m segments
- Plenum Ratings (more resistant to heating & burning)
- PVC (non-plenum)
- Riser rating—(in the middle of fire resistance, between plenum & PVC.)
- Crimping Cables
- Use a crimping tool to attach UTP (Unshielded Twisted Pair) cable to crimp (like RJ-45)
- Two standards: T568A and T568B
- Straight-through cable has same standard on each end
- Crossover cable has different standards on each end
- Structured Cabling (MDF) (Main Distribution Frame)
- Horizontal runs from wall outlet to patch panel through wall/ceilings
- Use punchdown tool to connect cable to patch panel
- Use tone generator/tone probe “Fox and Hound” to locate cables
- Use TDR for testing runs (TDR—Time Domain Reflectometer)
- UTP cables can be “solid core” or “stranded”.
