Chapter 4 - Network Topology and Technology Flashcards
Logical Topology
How data is transmitted between nodes and the way signals respond on network media.
Is a function of network protocols in use to transfer data across the network.
Physical Topology
The network layout of devices and how they’re arranged, connected and communicate with each other
Star Topology
Most common
Each node connects to a central hub or switch. Creating a central connection point for all systems
Star Advantages
Easy to implement
Easy to troubleshoot
Easy to upgrade
Star Disadvantages
If Sentra hub fails, everything connected is disabled.
Recommend implementation or redundancy
Ring Topology
Each ring node is responsible for passing information to and from each other.
Can only directly communicate to devices net to each other in the ring.
Information passes through to the next system till arriving at the destination.
Ring Advantages
Reduced collision chance.
Can us a token ring to prevent collision as information is out into a token that moves around to the needed device.
Ring Disadvantages
If one node goes offline it effects the entire network.
Mesh Topology
A system is connected to every other system on the network.
Makes many redundant connections with no central connection which makes it complex to implement.
Critical devices are normally set up as mesh for redundancy.
Mesh advantages
Withstand high traffic volumes
Redundancy
Expand network without interruptions
Mesh disadvantages
Difficult to manage
Expensive
Bus Topology (Linear Bus)
Network consists of a main trunk which devices are connected.
Needs two end points so signal doesn’t reflect back by using a terminator.
A terminator kills the signal with high resistance
All devices receive all messages
Bus advantages
Easy to set up
Inexpensive
Bus disadvantages
Limit to the size
Hard to troubleshoot
Venerable to wire tapping
Adhoc wireless
LAN
Built as devices are connected to each other and the wireless device
Adhoc Wireless advantages
Bribes need for a router Affordable Mobile Easy setup Fast to connect multiple devices and computers with no addition hardware
Infrastructure Wireless Network
Devices with connect to a wired network using an access point
WLAN extends the wired LAN to wireless devices
Infrastructure Wireless Advantages
Scalable
Uses wireless access points to reduce congestion and increase coverage
Move between access points without dropping connection
Infrastructure Wireless disadvantages
Complex
Costs more
Requires wireless access points
LAN
Local Area Connection
Smaller network typically in a room, building or group of buildings
Can be Ethernet
LAN Characteristics
Topology of arrangement of devices as start, ring or mesh
Protocol rules and encoding specifications
Media of cabling used
WLAN
Wireless LAN
Enables wireless network communication
Uses WAP
MAN
Metropolitan Area Network
Data network designed for a city or town
Connects multiple LANS
Can connect a central office to branches
MAN Benefits
Efficient
Fast communication
High speed carriers using fiber
Dedicated connections
WAN
Wire Area Network
Spans large geographical areas (Internet)
Can use a dedicated connection using a Telco company internet instead of public internet
CAN
Campus Area Network
Proprietary LAN used to Server a corporation, university or government agency
SAN
Storage area network
Specialised high speed network to storage granting block level access.
Communicate with hard drives arrays and can only access a dedicated portion of the array (Block Access)
High storage and performance using a dedicated connection
SAN Advantages
Able to offload app storage
Redundancy
Consolidation of resources
Tiered storage to access SSD or HDD depending on requirements
Data protection and security as everything is centrally locates
Use redundancy and dedicated staff at facility
IoT
Internet of Things
Growth of internet enabled devices and communication between them.
Laptops Smart Phones Watches Lighting Entertainment systems
Z-Wave
Wireless communication protocol Automated home devices like Heating, Ventilation, Aircon (HVAC) Home Cinema Security Systems Garage
ANT
Wireless communication protocol is open access wireless service technology
Uses 2.4GHz, sensor wireless type
Ultra low power
Used in fitness monitors for heart test, speed and temperature readings.
Bluetooth Smart
Energy efficient and low power compared to original Bluetooth
Most devices support it
Used for precise location finding and senses when you leave a room to turn off lights
NFC
Near Field Communication Contactless Supported by smart phones and tablets Fast Convenient Zero configuration Can use different protocols to transfer data
RFID
Radio Frequency Identification
Uses radio frequency waves in LF, HF and UHF Commonly used in chips and Access control cards Asset tracking Parking management Patient ID Inventory management
802.11 Wireless
Wireless networking Uses radio frequencies Low energy consumption Wider coverage range Supports IoT
Familiar home implementation with a wireless router(modem)
802.11 Standards?
- 11a (5GHz, 54mbps)
- 11b (2.4GHz, 11mbps)
- 11g (2.4GHz, 54mbps, compatible with 802.11b)
- 11n (both 2.4GHz and 5GHz, 300mbps, uses MIMO)
- 11ac (simultaneous use of 2.4 and 5GHz, compatible with b,g,n, 2.4GHZ @ 450mbps, 5GHz @ 1300mbps)
GSM
Digital Cellular
900MHz and 1800MHz
Digitises and compresses sata prior to sending.
TDMA
Time Division Multiple Access
Divides channels into three time zones.
Increase amount of data that can be carried.
Each channel is divided by time. Each device syncs to the time slot to accomodate multiple users on one channel.
What’s cellular technologies is TDMA?
Global System for Mobile Communications (GSM)
Digital Advanced Mobile Phone Service (DAMPS)
Personal digital cellular (PDC) morning
CDMA
Code division multiple access
Used in 2 and 3G
Form of multiplexing
Allows multiple signals on a single transmission to optimise bandwidth
Common in ultra high frequency 800 to 1.9GHz
Each transmission has a specific code. Your device only pays attention to that specific code which matches your connection.
CDMA Advantages
Good signal quality
Flexible resource allocation
Easily scalable
Compatible with other cellular technologies
CDMA Disadvantages
As network grows overall signal quality degrades
Frequency
Refers to the number of complete cycles in a single second
Measured from peak to trough
Low frequencies
Large radio wave lengths
High Frequency
Short radio wave lengths
IEEE 802.11 frequency ranges
- 4 to 2.5GHz
5. 15 to 5.876GHz
2.4GHz Stabdards
- 11b - 11mbps
- 11g - 54mbps
- 11n - 150mbps (20MHz channel width), 300mbps (40MHz channel width)
* Doubling channel width, doubles mbps through put*
2.4GHz advantages
Wider coverage
Better object penetration
Supports b, g, n
2.4GHz disadvantages
Greater interference
Less data speed
5GHz Standards
- 11a - 54mbps
- 11n - 150mbps (20MHz channel width), 300mbps (40MHz channel width)
- 11ac - 6.8gps with 8 antennas running 160MHz channel width.
5GHz advantages
Less congestion and interference
23 non overlapping channels
Supports higher network speeds of 802.11ac
5GHz disadvantages
Small signal area
Poor obstacle penetration
May not support older devices
Original IEEE 802.11 standard
2.4GHz
1 to 2 mbps
20ft range
802.11a
5GHz
54mbps
25 to 75ft range
802.11b
2.4GHz
11mbps
150ft transmission range
802.11g
2.4GHz
54mbps
150ft ranger
802.11n
2.4GHz and 5GHz
Up to 600 mbps
175ft range
Channel Bandwidth
Directly effects data transfer rates
- 11n 20/40MHz Channels
- 11ac 20/40/80/160MHz Channels
MHz is a measurement of how often something is sent. The higher it is the more data can be sent.
Channel Width
WiFi uses frequency and channels to transmit and receive data.
Default channels are 6 and 22 as they’re far apart, limiting channel overlap which reduces interference.
Eg Channel 6 bleeds into 4,5,7,8
Channel 11 bleeds into 9,10,12,13
Channel Bonding
Use in 802.11
Is when two adjacent channels using different frequencies and combined.
Increases device through put.
Provides additional functionality and increased through out
Reduces # of channels
Eg 2 20MHz channels and be bonded to make one 40MHz channel.
Channel bonding 2.4GHz
Support 3 non overlapping 20MHz channels
Total width 70MHz
Can only have 1 single bonded pair of 40MHz confirmed
Throughout up to 54mbps
Channel bonding 5GHz
Up to 25 non overlapping 20MHz channels
Total 500MHz width
More bonded pairs can be confirmed
Up to 160MHz using 802.11ac for high through out
MIMO
Multiple Inout Multiple Output
Wireless antenna technology.
Sends multiple signals at once using array of antennas.
Antennas combine to help minimise errors and optimise data speed.
Supports 802.11n and 802.11ac.
Single user MIMO
Multiple sessions at a time between each device which gets its own turn
Not as fast as multi user
Multi user MIMO
Multiple independent radio terminals to access a system
Enables 802.11ab max transfer of 6.93gbps
Usurps multiplexing to allow simultaneous communication with multiple devices.
Allows multiple users to simultaneously access the same channel and enhance performance.
Passive site survey
Access points for signal strength, Interface and coverage
Provides good overall picture of Wireless characteristics of network.
No connection to access points.
Active site survey
Gathers detailed information of
Network traffic patterns
Overall through put
Packet loss
Physical rates
You make connection to access points.
Predictive site survey
Performed with no field measurements
Utilises RF planning software tools for coverage
Used when site is being built to help planning and budget
Site survey documentation
Site maps Recommendations Issues relating to coverage, capacity and interference Heat map signal strength Future coverage after implementations
