CTS Networking Flashcards
Define a network
Two or more nodes interconnected so they can share data.
Networks have two main parts:
Nodes (any device that sends and receives data) and connections (physical means data travels from one mode to another).
Is a patch panel a node or a connection?
Connection!
Is a switch a node or a connection?
Node!
PAN?
Personal Area Network. Limited range wireless network that serves a single person or small workgroup.
CAN?
Campus area network. Communications network covers a group of adjacent buildings within the same organisation.
MAN?
Metropolitan area network. Network that covers a suburb or a city.
GAN?
Global area network. Network that spans the globe. The internet!
What are two ways you can categorise networks and which is better?
Geographically (PAN, CAN, MAN, GAN…) or whether nodes use physical or logical addresses to communicate. Second is better.
What does MAC address stand for?
Media Access Control Address
Do LANs use physical or logical address to communicate?
Physical. Uses the MAC address.
Describe a LAN (characteristics, not logistics).
privately owned and operated. Fast and high capacity. Required devices to be directly and physically connected.
Name 6 different kinds of LAN topology.
bus, ring, star, meshed, partially meshed, extended star.
Describe LAN bus topology.
All nodes connected through a single cable. Any node fails everything beyond it goes down.
Describe LAN ring topology.
Nodes are arranged in sequence like bus, but makes a circle. Info can go both directions, which makes redundant paths. If one node fails info still flows.
Describe LAN star topology.
All nodes connect to a single point (router, switch, hub). If one node fails info still flows. Central device is a single point of failure.
Describe LAN meshed topology.
Each node connects to every other node. Fast and redundant. Expense to create that many physical connections, though. Rare.
Describe LAN partially meshed topology.
Nodes connect to several other nodes, but not all. Good redundancy - several must fail at once to stop communication.
Describe LAN extended star topology.
A star with several layers of hierarchy. Device fails and everything below is cut off but the rest of the network works. Central device is still a single point of failure.
What is a WAN?
A network that connects one or more LANs together. WANs use logical address to communicate.
What is a logical address?
Usually an IP address (Internet Protocol).
What type of network uses a logical address?
WAN
What are the nodes on a WAN?
Routers. The router is at the top of the LAN network hierarchy.
What does the router do before sending info from the LAN to the WAN?
Strips the packet of identifying LAN information, like MAC addresses. This protects devices on the LAN.
Why can’t many networked AV protocols travel over WANs?
WANs are slower than LAN because they travel farther. Those extra fractions of a second add up and cause problems.
What do you call a private WAN?
An enterprise network. Secure government entities are likely to use these.
What are the two definitions of an enterprise network?
- Communication backbone of a large network. Every note connects to the core backbone.
- Any large, geographically dispersed private network.
Describe WAN hub and spoke topology.
Each LAN connects to a central location (branches connecting to corporate headquarters). Can have several layers of hierarchy like a star LAN.
Describe WAN common carrier topology.
Each LAN runs to an Internet service provider (ISP) backbone.
Describe WAN meshed topology.
Every LAN connects to every other LAN. Excellent redundancy.
What WAN and LAN topologies look like each other?
Star and Hub and Spoke.
Define Gateway
Connects a private network to outside networks. They translate data from one protocol to another.
Define Router
Routers forward data between devices that are not physically connected. In the Network Layer. Routers mark the border of the WAN and LAN.
Define unmanaged switch
Provides a physical connection between multiple devices. Switches collect and store MAC addresses for each connected device. Operate on the Data Link layer. No configuration options.
Define managed switch
Physical connection between multiple devices. Collects and stores MAC addresses. Data Link layer. Allows adjusting port speeds, setting up VLANs, etc. More common than unmanaged.
What does every device that connects to the network must have?
A NIC (network interface card) and associated MAC address. Some devices may have more than one NIC, esp if they have to connect to multiple networks. Each NIC will have it’s own MAC address.
MAC addresses are part of what standard?
IEEE 803
A MAC address is how many bits and looks like what?
48-bit consisting of 6 groups of hexadecimal numbers separated by hyphen or colon.
What do the parts of a MAC address mean?
First part tells the manufacturer, second is serial number.
Is Ethernet connection baseband or broadband?
Baseband (uses entire frequency range of the cable to send data)
What does a switch do if it gets an Ethernet frame addressed to an unfamiliar MAC address?
Sends it out to everything on the network except the node it arrived on. If the device it was intended for gets the info the switch will receive an acknowledgement that the packet arrived and will update it’s lookup table.
What’s the difference between a switch and a hub?
A hub broadcasts frames to all ports, including the one on which it received the frame.
What is Ethernet?
A family of computer networking technologies for LANs
Data over Ethernet separates streams of data into shorter pieces called what?
Frames.
What does each frame contain?
Source and destination addresses, and error checking data.
What is full duplex (in regards to Ethernet)?
Means the switch and station can communicate with each other simultaneously. This makes Ethernet completely collision free.
What’s the difference between a frame and a packet?
Frames happen in the Network Access Layer (data link, physical). Packets happen on the Internet layer, or Network layer.
Describe a hub.
Half-duplex. Can send and receive data, but not both at the same time. All devices have to share the network’s bandwidth. Slow down networks a lot and aren’t used anymore much.
What is a server?
Not a piece of hardware – a role a piece of hardware can play. Almost any hardware can be used as a server. Provides services to dependent nodes.
Two definitions of what a server can be:
- ) A server is a piece of hardware that does nothing but provide services.
- ) A server can also be a program that runs on a computer with other programs.
How are servers usually named?
After the service they provide.
Why would a server need to be it’s own device?
- ) It needs the CPU power and storage capacity.
2. ) It’s mission critical and needs a separately maintained device.
What’s a thin server?
A server that offers only one service. Can be on dedicated hardware or a virtualized instance configured with only functionality needed to provide the service.
Name the parts of the electromagnetic spectrum in order of increasing frequency and/or increasing wavelength.
Radio and TV, Microwave, Infrared, Visible light, Ultraviolet, X-ray, Gammaray.
Name 3 different ways of transmitting electromagnetic energy.
- Copper (as voltage)
- Glass (as visible light)
- Air (as radio frequencies)
What’s the benefit of twisting wires in a cable run?
Makes sure each wire is subjected to the same outside interference. This lets the resulting noise be canceled out in the input circuit. Protection from electromagnetic interference at low frequencies.
Name and describe 2 kinds of twisted pair cable.
- ) UTP (unshielded twisted pair). Lighter weight, more flexible, lower cost.
- ) STP (shielded twisted pair). Gives greater bandwidth (?) and longer cable runs.
What are the “Cats” in Ethernet?
Categories of twisted pair cable under EIA/TIA 568 Ethernet standards.
What CATs are currently unrecognized by TIA/EIA?
CAT 1 - CAT 5
What twisted pair cable is used for telephone and doorbell type connections?
CAT 1
What twisted pair cable has speed up to 100 MHz (typically 100 Mbps)?
CAT 5
What twisted pair cable has speeds up to 20 MHz (typically 16 Mbps)
CAT 4
What twisted pair cable has speeds up to 250 MHz (typically both 100 Mbps and 1 Gps)
CAT 5e (defined in TIA/EIA-568-B)
What twisted pair cable has speeds up to 500 MHz (typically both 100 Mbps and 1 Gps)
CAT 6 (defined in TIA/EIA-568-B)
What’s the speed of CAT 6a cable?
up to 500 MHz - typically 10 Gbps (defined in TIA/EIA-568-B.2-10)
What’s the speed of CAT 7 cable?
up to 600 MHz - typically 10 Gbps (Informal - ISO/IEC 11801 Class F cabling)
What twisted pair cable is 100-ohm unshielded and associated with connecting hardware specified for data transmission up to 100 Mbps?
CAT 5
What makes CAT 5e different from CAT 5?
CAT 5e adds specs for far end crosstalk to the obsolete Cat 5 standard.
What CAT is a standard for Gigabit Ethernet?
CAT 6.
What makes CAT6 different from the earlier CAT standards?
- Adds more stringent specs for crosstalk and noise.
- Has more twists per inch.
- Operate at a high speed (measured in gigabits) so they have tiny wavelengths. Should be shielded.
(Also - is backward compatible with CAT 5, CAT 5e, CAT3)
What cable should be used for AV signals like HDBaseT?
Shielded CAT 6
What’s the maximum distance of CAT 5e and CAT 6?
328 feet or 100 meters.
What standards regulate Plenum cable?
International NFPA-262 and American UL-910 standards.
What makes Plenum cable different?
In a fire it must self extinguish and not reignite. Also produces less smoke and is less toxic.
What is riser cabling?
Cables used in vertical tray applications. Cable must self-extinguish and prevent flame from traveling up the cable in a vertical burn test. Must comply with UL-1666 standards.
What is a vertical tray application?
Cable runs between floors, cable risers, or in elevator shafts.
What’s the connector used for Cat cabling?
RJ-45
How many wires do many Ethernet connections use?
4 out of the 8. For Gigabit Ethernet or faster (or for special devices) the other 4 conductors can be used for other purposes.
What are the two wiring formats for RJ-45 in the IEEE 802 standard?
T568-A and T568-B
What’s the difference between T568-A and T568-B?
T568-A uses green wires for transmit and orange wires for receive. T568-B uses orange for transmit and green for receive.
What is a crossover cable?
An Ethernet cable with T568-A on one side and T568-B on the other. Allows two devices to connect and share info without the use of a switch or router.
When would you use and when would you not use crossover cables?
Use: to connect a network device console port to a computer to make config changes. In data closets!
Don’t use: network infrastructure in TCP/IP networks.
What are the three layers of fiber?
Core (glass, carries light)
Cladding (used to reflect light back onto the core)
Coating (protects fiber)
What are the benefits of fiber?
- High bandwidth
- Immune to EMI and RFI (total electrical isolation)
- Very little signal degradation over long runs.
- Withstands aging and corrosion well.
- More secure than copper or radio.
Differences between single mode and multimode fiber?
- Single-mode is smaller diameter and the signal path is mostly straight.
- Multimode has some signal that goes straight but a lot bounces off the cladding. Slower and more signal loss.
How long can single-mode fiber run?
2000 meters, usually. Some can support 18.6 miles (30 km)
What is modal bandwidth?
Fiber’s ability to carry data over distance. Measured in (MHz/km)
What is OM?
Optical Multimode
What are the 4 parts of a fiber connector?
- Ferrule (holds fiber in place. The part you cant touch, I think)
- Connector body (holds ferrule and fiber in place)
- Cable (attaches to connector body to be point of entry for fiber)
- Coupling device (used to mate connectors of the same gender)
What are the 5 kinds of fiber connectors?
ST, LC, SC, Hermaphroditic, Expanded beam
What three fiber connectors are the most common for AV?
ST, LC, and SC
Describe the ST connector
Very similar to BNC. Bayonet, which keeps fiber and ferrule from rotating during connection. Used on both multimode and single-mode.
Describe the LC connector
Much smaller than the ST and used for basic wiring. Called a “push-pull” connector. Has great low loss qualities.
Describe the SC connector
Larger than LC. “Stab and click”. Great for tight spaces. (What we use here).
Describe the Hermaphroditic connector
Genderless. Identically paired male and female parts so can be connected to any other hermaphroditic connector. Only can be used for fiber optics.
Describe the expanded beam fiber connector.
Works great outside - resistant to dust and dirt and easy to clean.
What is a network device that handles a wireless network connection?
An access point.
What determines the speed of a wi-fi connection?
The RF signal strength, the revision of 802.11 with which you connect, the number of users connected.
What 802.11 has a frequency band of 2.4 GHz and a typical throughput of around 22 Mbits/s
802.11g
What’s the frequency and throughput of 802.11n?
5 GHz and/or 2.4 GHz / around 144 Mbits/s (up to 600 Mbit/s)
What two 802.11 are in the 2.4 GHz range?
802.11b, 802.11g (and sometimes 802.11n)
What two 802.11 are in the 5 GHz range?
802.11a, 802.11n
What’s the maximum devices that can connect to a Bluetooth network?
7
What frequency band does bluetooth operate in?
2.45 GHz
What’s the maximum range of Bluetooth?
10 meters
How fast is Bluetooth?
1 megbit/second (up to 2 Mbps in second gen)
What’s an ad-hoc network?
peer-to-peer networking. Not centrally managed or administratively controlled. (Bluetooth can only be ad-hoc, most 802.11 devices can create or join ad-hoc networks)
5 advantages of wi-fi
- Convenient
- Mobility can equal productivity. Work can be accomplished from anywhere.
- Require little infrastructure. Quite close to plug and play.
- Scalable. Easy to add more access points.
- Cheap. Don’t need as much cable, connectors, install, etc. Just drop an access point.
6 disadvantages of wi-fi
- Limited range. (Range restricted by 802.11 standards)
- Susceptible to RFI (Radio frequency interference)
- Selection and placement can be tricky.
- Can get expensive. Extended networks require directional antennas, repeaters, etc.
- Slow. Bandwidth is capped at 150 Mbps. NOT DEPENDABLE FOR STREAMING VIDEO!
- Insecure. Much easier to hack.
What does OSI stand for?
Open Systems Interconnection model
What are the 7 layers of the OSI model?
Application, Presentation, Session, Transport, Network, Data Link, Physical
What three layers are in the Media Layers?
Physical, Data, and Network
What 4 layers are in the Host Layers?
Transport, Session, Presentation, Application
When a computer send a message what layer does it start on?
Layer 7 - application layer
Application Layer
Layer 7. Gives applications access to network services (email, FTP transfers, databases). Defines how users access and interact with data on the network.
Presentation Layer
Layer 6. Translates data to an intermediate form that masks differences between types of data. Also compresses data, encrypts, decrypts.
Session Layer
Layer 5. Allows two applications on different devices to talk. Establishes, manages, and ends sessions. Regulates which side transmits, when and how, etc…
Transport Layer
Layer 4. Manages end-to-end message delivery. May divide long packets into smaller segments, builds them back together. May also detect errors and send receipt acknowledgements. PORTS are in this layer.
Network Layer
Layer 3. Addresses data packets and routes them to their addresses on the network. Translates between physical addresses and logical addresses. PACKETS are in this layer.
Data Link Layer
Layer 2. Responsible for transferring data from one device to another without errors. Switch to switch or router to router. Converts packets into frames, adding MAC addresses. FRAMES are in this layer.
Physical Layer
Layer 1. Defines physical means of sending bit of data between devices. Doesn’t change the data in any way. BITS are associated with this layer.
Web browser requests info using HTTP on this layer
7 - Application Layer
Ethernet frames transmitted from wireless router to laptop.
1 - Physical Layer
SDP (Session Description Protocol) invites participant devices to a web conference and negotiates what kind of media each device can send and receive.
5 - Session Layer
LAN switches forward Ethernet frames to the MAC addresses of connected devices. Data is addressed to MAC address within the LAN.
2 - Data Link Layer
Data is address to an IP address. Network routers identify the device the IP address refers to and sends the data along the most logical route.
3 - Network Layer
TLS (Transport Layer Security) is used to encrypt and decrypt data. Sends private data over the internet.
6 - Presentation Layer
Audio and video are sent using UDP (User Datagram Protocol). UDP continuously sends media packets to their destination without waiting for receipt confirmation.
4 - Transport Layer
Pneumonic for OSI Model
Please Do Not Throw Sausage Pizza Away.
Physical, Data Link, Network, Transport, Session, Presentation, Application
What is UDP?
User Datagram Protocol. A generic packet format for carrying data on IP networks. Does not interfere with timing of delivery so works better for realtime data than TCP.
What is unicast?
When packets are directed from a single source to a single destination. (Compare with multicast).
What is TCP?
Transmission Control Protocol. A transmission system for reliable communication across the internet. TCP deals with timeouts, retransmissions, and making sure all data arrives even with hiccups in the underlying network.
What is bufferbloat?
Excess buffering of packets in network equipment. Queuing delay becomes extreme and network may become unusable for time-critical applications such as media networking.
What is flooding?
The process of forwarding packets to all other destinations on a network. Happens when the location of the addressed destination is unknown. Gear that doesn’t support PIM or IGMP may flood all multicast traffic.
Bits, frames, and packets - associated with which layer of the OSI model?
Bits = physical. Frames (on LAN) = data link. Packets (frames broken into packets to go to WAN) = network.
This layer presents network data to the software.
Application.
This layer transfers data directly from one device to another. Sends frames to their physical destination.
Data link
This layer makes data look the same on the network and makes sure only authorized users see data.
Presentation layer.
This layer controls interaction between devices - initiates and terminates communication.
Session layer
This layer manages end to end delivery - may divide packets into smaller segments and check for receipt.
Transport layer
This layer applies IP addresses to packets and routes them to their remote locations.
Network layer
This layer defines means of data transmission. Includes encoding methods and cable and connector standards.
Physical layer.
What’s a WLAN?
A Wireless local area network.
What’s a SAN?
A storage area network. High speed, special purpose network or subnet that interconnects different kinds of data-storage devices.
What’s a VLAN?
A virtual local area network. Created when network devices on separate LAN segments are joined together to form a logical group.
This network topology is used most ofen in control systems, like lighting control.
Bus topology.
Ring topology is used commonly where?
For phone services. WAN internet services use a mesh ring topology to create redundancy.
What does IEEE stand for?
Institute of Electrical and Electronics Engineers
IEEE 802 is what?
Ethernet standard. Specifies physical transmission media (cable) and how signal info is handled (frames and packets)
Ethernet is a ______ based system.
Packet.
How big is a packet?
1,5000 bits or smaller.
Give an example of an 8P8C (eight position, eight conductor) connector?
RJ-45
How does a crossover cable work?
Each NIC has a transmit pair and a receive pair. If they are crossed, the computers can talk! If they are wired to the same standard the transmit will be “received” by the transmit pair.
Fiber can reach LAN at speeds of… ?
10 and 40 gigabits/sec (Gbps)
Which type of fiber usually is yellow?
Single-mode
Which type of fiber usually is orange?
Multi-mode
What does the IEEE 802.11 standard define?
MAC and Physical layer specs for
WLAN in the 2.4, 2.6, 5, and 60 GHz bands.
Which 802.11 revisions can suffer from interference from microwave ovens, cordless telephones and Bluetooth device? Why?
802.11b and 802.11g. Because they both use 2.4 GHz.
What is the application layer?
- This layers interact with OS or application.
What is the Presentation layer?
Layer 6. Takes the data provided by the Application layer and converts it into a standard format that the other layers can understand.
What is the transport layer?
- Maintains flow control of data and provides for error checking and recovery of data between the devices. Flow control means that the Transport layer looks to see if data is coming from more than one application and integrates each application’s data into a single stream for the physical network.
What’s the network layer?
- Determines the way data will be sent to the recipient device. Logical protocols, routing and addressing are handled here.
What’s the data link layer?
- Appropriate physical protocol is assigned to the data. Also, the type of network and the packet sequencing is defined.
What’s a protocol stack?
group of protocols that all work together to allow software or hardware to perform a function.
Example of a protocol stack?
TCP/IP protocol stack is a good example. It uses four layers that map to the OSI model.
What layer breaks down large streams of info into segments?
Layer 4 - transport.
At what layer is destination and control info added to the segment to form a packet?
Layer 3 - Network
At what layer are packets encapsulated into frames that contain info about physical destination?
Layer 2 - Data link
