Terminology Flashcards
Workgroup (when talking of a LAN)
An administrative segment of a LAN to make it easier to manage.
Workgroup (when talking of a domain)
A set of devices with no security association with one another.
Workstation
Powerful computer, possibly with more than one CPU, whose resources are available to other users on the network.
Don’t provide resources to the huge number of users that a server does.
Server
Provide resources to the users on a network, often very specialised, and running a network operating system.
Client
Any device on a network that can ask for access to resources.
Hosts
A very loosely used term. For the exam think of them as network devices with IP addresses. Could be servers, workstations or clients.
LAN
Local Area Network, usually restricted to a particular geographic location, like a building, department, floor or home office.
MAN
Metropolitan Area Network. Covers a metropolitan area, something like a concentrated MAN.
WAN
Wide Area Network. Typically uses routers and joins disparate locations and networks using telco links. The internet is a WAN.
PAN
Personal Area Network. Usually bluetooth, infrared, zigbee etc. Range just a few meters.
CAN
Campus Area Network. Connects a group of buildings such as a campus or business park
SAN
Storage Area Network. Typically only found in data centres, use specific protocols for data storage.
SDWAN
Software-Defined Wide Area Network. A virtual WAN that uses software to to manage connectivity.
MPLS
Multi Protocol Label Switching
What are 4 advantages of MPLS?
- Physical layout flexibility
- Prioritising of data
- Redundancy in case of link failure
- One-to-many connections
mGRE
Multipoint Generic Routing Encapsulation
used to create point-to-multipoint tunnels
DMVPN
Dynamic Multipoint VPN
used to create dynamic VPN networks with multiple sites without needing to re-configure multiple endpoints
Peer-to-peer networks (what are their main characteristics)?
- Do not have central authority
- Security is the responsibility of each user, not centralised
- Each host can be both a client and a server
- No network operating system
Client-Server networks (what are the main characteristics)?
- Uses a network operating system
- Central management
- Easy scalability
- Tighter security, uniform password management
Another name for a star topology?
hub and spoke topology
Ring Topology - to remember for exam
Unless they specify, when they say a ring topology, they mean FDDI, and FDDI has redundancy (two rings operating in different directions)
How to calculate links in a mesh topology?
Where n is number of endpoints:
n(n-1)/2
5 things to consider when selecting a network topology?
- Cost
- Ease of installation
- Ease of maintenance
- Fault-tolerance requirement
- Security requirement
Network backbone (very loose definition)
What all the segments and servers connect to
Network segment (very loose definition)
A small piece of the network that can be connected to, but isn’t a piece of the backbone.
Generally used to organise departments, workgroups etc.
NFV
Network Function Virtualisation
OSI
Open Systems Interconnection
List the 7 layers of the OSI model, from layer 1 to layer 7
- Physical
- Data Link
- Network
- Transport
- Session
- Presentation
- Application
5 functions of the OSI application layer
File,
print,
message,
database,
application services
3 functions of the OSI presentation layer
Data Encryption,
compression,
translation services
Function of the OSI session layer
Dialog control
Function of the OSI transport layer
End-to-end connection
Function of the OSI network layer
Routing
Function of the OSI Data-Link layer
Framing
Function of the OSI physical layer
Physical topology
“Reliable networking” (as when TCP is involved), means what three things will be used?
- acknowledgements
- sequencing
- flow control
TCP establishes a ____ ____
virtual circuit
What does TCP do to establish a virtual circuit?
A three-way handshake
What else do the two TCP processes agree during the three-way handshake
The amount of information that will be sent in either direction
What do we call the cost of setting up a virtual circuit?
overhead
What is the first part of a three-way handshake?
SYN - a request for synchronisation
What is the second part of a three-way handshake?
SYN/ACK - acknowledge the request and establish connection parameters
What is the third part of a three-way handshake?
ACK - notifies the receiving host that the connection agreement has been accepted
Which OSI layer deals with flow control
Layer 4 - Transport
In simple terms, what does flow control provide?
A means for the receiver to govern the amount of data sent by the sender.
What is a TCP window
The amount of data (in bytes) that a sender can send without receiving an acknowledgement
What are the two types of packets used at the network layer?
- Data Packets
- Route-Update Packets
What are the 3 pieces of information on a routing table?
- Network Address
- Interface (the exit interface for this network)
- Metric (the “distance” to the network)
Do routers forward multicast packets by default?
No
What is Media Access Control concerned with? (7)
- How packets are placed on media
- Physical addressing
- Logical topology
- Line discipline
- Error notification
- Ordered delivery of frames
- Flow control (optional)
What is Logical Link Control concerned with? (2 + 2)
- Identifying network layer protocols
- encapsulating them
can also provide flow control and sequencing of control bits.
DTE
Data Terminal Equipment
DCE
Data Communication Equipment, or
Data Circuit-terminating Equipment
What are the services available to the DTE accessed via?
The DCE which is a modem or CSU/DSU
CSU/DSU
Channel Service Unit/Data Service Unit
The 5 typical steps of encapsulation are?
- User information is converted to data
- Data is converted to segments and a reliable connection set up (or not)
- Segments are converted to packets or datagrams and a logical address added.
- Packets or datagrams are converted to frames. A hardware address is added.
- Frames are converted to bits, and a digital encoding and clocking scheme used.
Modulation
Process of varying one or more properties of a waveform (carrier signal)
What are the three types of cabling popularly used in networks?
- Twisted pair
- Coaxial
- Fibre optic
What is twinaxial cable used for
Short-distance high speed connections (such as 10G ethernet in a data centre)
SMF
Single-mode fibre
MMF
Multi-mode fibre
Pros of Fibre optic (2)
Immune to EMF and RFI
Transmit up to 40km
Cons of Fibre optic (4)
Expensive
Difficult to install
Harder to troubleshoot
Troubleshooting equipment is expensive
APC
Angled physical contact
UPC
Ultra physical contact
ST connector
Straight tip
(stick and twist)
SC connector
Square connector or
subscriber connector
(stick and click)
FDP
Fibre Distribution Panel
SFF connector
Small form factor connector
MTRJ
Mechanical Transfer Registered Jack
LC
Local Connector
(love connector)
SFP
Small Form-Factor Pluggable. Compact transceiver.
SFP+
Enhanced Small Form-Factor Pluggable.
Data rates up to 16Gbps
QSFP, QSFP+, QSFP28
Quad Small Form-Factor Pluggable. A hot pluggable transceiver that interfaces networking hardware with fibre cables.
4 * 1 Gbps
4* 10 Gbps for QSFP+
4*28Gbps for QSFP28 used for 100G links.
What is 100m in feet?
328 feet.
How do you identify pin 1 on an RJ45 coupler.
Pin one is on the left, when the clip is facing away from you, and the cable is hanging towards the ground.
What is straight-through cable used for?
To connect a:
Host to a switch or hub, or a
Router to a switch or hub.
What standard ethernet required four pairs of wires?
1000BaseT and above
What is a crossover cable used for?
Switch to switch
Hub to hub
Host to host
Hub to switch
Router to host
How are the pins paired in Gigabit crossover?
1 to 3
2 to 6
3 to 1
4 to 7
5 to 8
6 to 2
7 to 4
8 to 5
How is a rollover cable pinned?
1 to 8
2 to 7
3 to 6
4 to 5
5 to 4
6 to 3
7 to 2
8 to 1
How is a T1 crossover pinned
1 to 4
2 to 5
4 to 1
5 to 2
How many pairs does a 66 block terminate?
25
How is a 110 block different from a 66 block
A 66 block is laid out in rows of 4, a 100 block uses a layered system with wafers. A 110 can have RJ-11 or RJ-45 connectors on the other side.
How do you tell a 110 block from a Krone block?
The connectors on a krone block are angled.
What is a NID or NIU
A network interface device or unit. Often can be looped for testing purposes by the service provider.
When a host, using CSMA/CD hears another signal on the line it is transmitting on, what does it do?
It sends out an extended jam signal
In CSMA/CD, what do hosts respond to a jam signal?
They stop transmitting and initiate their random back-off algorithms.
In CSMA/CD, how many retries before a host times out?
15
In CSMA/CD, which host has priority to transmit after their timers have expired?
All hosts have equal priority.
In a CSMA/CD network, what is the effect of sustained heavy collisions? (3)
- Delay
- Low throughput
- Congestion
What is broadband?
Using Frequency division multiplexing, to divide our bandwidth into multiple channels, and use them to process multiple signals on the same wire at the same time.
What is baseband?
All the bandwidth of the physical media is used by only 1 signal.
What is bit rate?
The number of data bits transmitted in a second.
What is baud rate?
The number of electronic state changes in a second (this could involve more than one bit per change)
What network device can’t operate in full duplex mode?
Hub
Are there any collisions in full duplex mode
No
How many switch ports are required for a full duplex host?
One
What is sequence of values for subnetting (in decimal)
128
192
224
240
248
252
254
255
MAC (address)
Media Access Control
