Chap 1: Networking Intro
I. Topologies
~~Wired Below~~
- Bus:
- Uses a backbone to connect all network using T connectors
- Needs to be grounded
đĄ
Loose or missing terminators from a bus network disrupt data transmissions
Adv/Disadv
| Advantage | Disadvantage |
|---|---|
| Cheap/Easy to implement | Network disruption when computers are added/removed |
| Requires less cable | Break in cable prevents system from accessing network |
| Doesn't use specialized equipment | Difficult to troubleshoot |
2. Ring:
- Data goes from 1 computer to another. 1 node fails = whole fails
- Token ring â MSAU (Multistation Access Unit) acts like switch where RI is connected to RO
Adv/Disadv
| Advantage | Disadvantage |
|---|---|
| Cable faults are easily located | Network expansion causes disruption |
| Easy to install | Single cable break = network fails |
3. Star
- All nodes connect to central hub/switch, each using a single cable â Expand using only a single cable (Easiest to expand)
- Single point of failure is the hub/switch
- High cost because cables
Adv/Disadv
| Advantage | Disadvantage |
|---|---|
| Easily expanded | But requires more cable |
| Cable failure affects one node | But single point of failure in switch/hub |
| Easy to troubleshoot/implement | Needs additional equipment to create layout |
4. Wired Mesh
- Every node connects to each other â Redundancy
- Complicated wiring â High cost, difficult
- Hybrid mesh = partial
đĄ
Because of the redundant connections, mesh topology has better fault tolerance
Adv/Disadv
| Advantage | Disadvantage |
|---|---|
| Provides redundancy | Requires more cable |
| Can be expanded without disruption | Difficult to implement |
~~Wireless Below~~
- Infrastructure
- Used to extend wired LAN to include wireless devices, bridged by AP
- All communicate through AP
2. Ad Hoc
- Nodes talk among themselves, no AP
- Small number of nodes
3. Wireless Mesh
- Fairly common, no cables
- AP attached to wired network
- Self-healing, scalable, reliable (high redundancy), BUT high cost
4. Hybrid
II. Network types
1, LAN
- Restricted to single location, small area
- High speed, cheaper than WAN
2, WLAN (Wireless LAN)
- Uses RF signals to tx/rx data
- Uses access points
- Secure, augments/replaces LAN
3, WAN (Wide Area Network)
- Spans > 1 geographic location
- WANs slower than LANs, also costly and hard to implement
4, MAN (Metropolitan)
- 1 geographic area (campus,city)
- MAN is a WAN, but bigger
5, CAN (Campus)
- Within an area, connects buildings
- CAN is a WAN
6, SAN (Storage)
- Contains shared storage devices
- SAN is subset of LAN, only provides block-level ops by itself
7, PAN (Personal)
- LAN to share data among your devices
- WPAN = Wireless PAN
- Bluetooth, Adhoc sometimes used
III. IoT Technologies
IOT
| Name | Function |
|---|---|
| Z-Wave (Danish Co.) | - HVAC, home cinema, system control - Requires Z-Wave gateway (control device) - ⤠232 devices on a Zwave network |
| Ant+ (Garmin) | - Wireless Protocol, 2.4GHz range - Control lighting systems, TV sets - MCU with ANT module - Bidirectional, serial msgs across a channel (master/slave) |
| Bluetooth (SIG) | - 2.4-2.485 GHz, based on IEEE 802.15.1 - 79 channels available, each 1 MHz - Currently Bluetooth 5 (2 Mbps) |
| NFC - Near Field Comms | - Device close to the AP â Used for payment |
| IR - Infrared (IrDA) | - Uses IR beams, 10-16 Mbps - Normal vs diffused (no LOS needed, but close range) - Uses less power, is secure, no signal conflicts |
| RFID | - Readers work with 13.56 MHz cards / 125 KHz proximity cards - Used for door opening |
~~~802.11~~~
802.11 Standards
| Name | Function | Range |
|---|---|---|
| a | - Up to 54 Mbps | 5 GHz band - Most commonly at 6, 12, 24 Mbps - Incompatible with b and g | 25-75 feet indoors, affected by materials |
| b | - Up to 11 Mbps | 2.4GHz band - Can do 1, 2, 5.5 Mbps - Compatible with g | Up to 150 feet indoors, affected by materials |
| g | - Up to 54 Mbps | 2.4 GHz band | Up to 150 feet indoors, affected by materials |
| n | - Common at 100 Mbps, can reach 600 - Both 2.4 and 5 GHz - Multiple In, Multiple Out | 175+ feet indoors, affected by materials |
| ac (newest) | - 5 GHz only - 500 Mbps (1 link), up to 1.3Gbps (multilink) - Up to 8 MIMO streams / 4 MU-MIMO clients | 115+ feet indoors, affected by materials |
| 802.11 (oldest) | - 2.4 GHz - 1 to 2 Mbps | 20 feet indoors |
MIMO multiplexing
- Combines multi signals for transmission over a single line
- Increases range/speed of wireless networking
- Transmit multi data streams on different antennas at the same time in same channel
Channel Bonding
- Use 2 channels at the same time
- CAN up the rate to 600 Mbps with 802.11n
- n uses Ortho Freq Division Multiplexing (OFDM)
Spread spectrum
- Manner in which data travel through a radio freq
- Data doesn't travel straight (narrowband transmission)
- Has 2 types: Freq hopping (FHSS) and Direct sequence (DSSS)
FHSS (Frequency-Hopping Spread-Spectrum)
- Narrowband signals change freqs with predictable pattern
- Resists interference + environmental factors â Use in large area
- Not the preferred tech for today
DSSS (Direct-Sequence Spread-Spectrum)
- Signals spread over full spectrum
- 32-bit Chip pattern sent for every bit of data sent â Secure
- Resists interference and noise
- Has better security and delivery than FHSS, but sensitive to environment
OFDM (Ortho Freq Division Multiplexing)
- Transfers large amounts of data over 52 freqs by splitting signals
- a, g, n, ac uses OFDM. 4G too
- OFDMA (multiaccess) = simul data transmission from multiple users
I was going to do chapter 2 as well, but then I passed Network+ after 5 days of study anyway LMAO
Resources that helped:
- Prof. Messer's playlist
- Emmett Dulaney et. al's N10-007 Exam Cram book
That's it. If you look around the Internet, there will be quite a few sites with old exam questions ("dumps"). I don't recommend you look at these unless you absolutely have to, since some of the questions may not have the right answer attached to them.
Good luck with studying!