2.2 Compare & contrast common networking hardware Flashcards
1
Q
What is the Internet?
A
Global network of networks
2
Q
What does the core of the internet consist of?
A
Fiber optic links connecting IXPs
IXPs (Internet eXchange Points) are locations where ISPs and network operators interconnect their networks
3
Q
Why do ISPs use transit & peering arrangements?
Transit is a paid arrangement where an ISP buys access to the broader internet from another ISP. Peering is a mutual agreement between 2 ISPs to exchange traffic directly without charging each other, usually at IXPs. This ensures the ISP’s customers can access external websites, services, and networks.
A
To control traffic beyond their network boundaries
Meaning to & from parts of the Internet they don’t directly control
ISPs are tiered based on their reliance on transit arrangements.
4
Q
What is a transit arrangement in internet connectivity?
A
When an ISP pays another ISP to route traffic to destinations it doesn’t serve
5
Q
What is a peering arrangement in internet connectivity?
A
When ISPs exchange traffic between their networks without payment
6
Q
How do users connect to the ISP’s network?
A
via the ISP network’s nearest Point of Presense (PoP)
i.e. a local telephone exchange
7
Q
What is an Internet connection type?
A
Media, hardware, & protocols for connecting to ISP’s PoP
PoP = Point of Presense
i.e. Satellite, Fiber, Cable, DSL, Cellular, & WISP
8
Q
What does it mean that a WAN interface is typically point-to-point?
A
There are only 2 devices connected to the media
Unlike Ethernet where multiple devices can be connected through switches
9
Q
What do modems do?
A
Establishes the physical connection to the WAN interface
A WAN interface is a network interface on a network device to connect to a WAN
10
Q
What do routers do?
A
Use IP to route and forward data between networks
IP = Internet Protocol
11
Q
Meaning of ISP?
A
Internet Service Provider
12
Q
What global telecom network do many internet connections use?
A
PSTN
PSTN = Public Switched Telephone Network
13
Q
What cabling is used at the core of the PSTN?
PSTN = Public Switched Telephone Network
A
Fiber optic
14
Q
What cabling is used at the edge of the PSTN?
PSTN = Public Switched Telephone Network
A
Copper
15
Q
What is the edge of the PSTN referred to as?
A
POTS, “local loop”, or “last mile”
POTS = Plain Old Telephone System
16
Q
How does DSL work?
A
Using the PSTN’s POTS as the communication channel
Meaning the PSTN’s copper cabling is used (the edge)
PSTN = Public Switched Telephone Network | POTS = Plain Old Telephone System
17
Q
Meaning of DSL?
A
Digital Subscriber Line
18
Q
2 types of DSL?
A
- ADSL
- SDSL
19
Q
How does ADSL differ from SDSL?
A
Providing a fast downlink but a slow uplink
20
Q
How does SDSL differ from ADSL?
A
Offering the same uplink & downlink speeds
These connections are ideal for businesses and branch offices, with higher upstream data transfer.
21
Q
How are LANs connected to the telephone cabling in DSL?
A
Via DSL modem
DSL modems can be a standalone device or be embeded as a function of a SOHO router
22
Q
What does the DSL modem’s RJ11 WAN port connect to?
A
Phone point
23
Q
what does the DSL modem’s RJ45 port connect to?
A
Router
24
Q
Why does DSL require splitters at each phone socket?
A
To separate voice & data signals
splitters can be self-installed on each phone point or it may be integrated into sockets
25
How is cable internet provided?
CATV services
## Footnote
CATV services are aka HFC, Broadband Cable, & Cable
26
Meaning of CATV?
Cable Access TV
27
Why are CATV networks described as HFC?
| Hybrid Fiber Coax
Integrates fiber optic core with copper coaxial cables for customer connectivity
28
Downlink bandwidth of Cable internet based on DOCSIS?
## Footnote
DOCSIS (Data Over Cable Service Interface Specification) defines the standards for transmitting data over cable TV systems.
- 38 Mbps (North America)
- 50 Mbps (Europe)
29
Uplink bandwidth of Cable Internet based on DOCSIS?
## Footnote
DOCSIS (Data Over Cable Service Interface Specification) defines the standards for transmitting data over cable TV systems.
27Mbps
30
Cable used to connect cable modems to routers?
RJ45 cable
31
How do cable modems connect to the access provider's network?
Via coaxial cable with F-type connectors
## Footnote
Coaxial cable links premises to a CMTS in a street, which sends data traffic to the ISP's PoP and then to the Internet via fiber backbone.
32
Meaning of FTTx?
Fiber To The X
33
Purpose of FTTx?
Upgrade last-mile connectivity using fiber optic cables
| This is done for higher internet bandwidth
## Footnote
FTTx is an initiative to to deploy fiber optic technology closer to end-users
34
2 types of FTTx projects?
- FTTC
- FTTP
35
Meaning of FTTC?
FTT Curb
36
Meaning of FTTP?
FTT Premises
37
How does FTTC work?
Extends fiber link to a cabinet for multiple subscribers
| Copper wiring is still used to connect to customers
38
How do DSL service providers support FTTC?
via VDSL
39
Meaning of VDSL?
Very high-speed DSL
40
How does VDSL differ from other DSL types?
Achieves higher bit rates at the expense of range
| VDSL allows for symmetric & asymmetric modes
41
asymmetric downlink bandwidth of VDSL?
52 Mbps
42
asymmetric uplink bandwidth of VDSL?
6 Mbps
43
Symmetric bandwidth of VDSL?
| bandwidth is the same on up & downlink
26Mbps
44
What does VDSL2 specify?
A very short range rate of 100Mbps (bi-directional)
| short range is 100m/300 feet.
45
What does it mean that DSL modems are not interchangeable?
A DSL modem of 1 type may not support a different type of DSL
## Footnote
An ADSL modme is unlikely to support VDSL, though most VDSL modems support ADSL
46
How does FTTP work?
Connecting ISP's fiber optic cable directly to customer's building
47
How is FTTP implemented as?
PON
| (PON = Passive Optical Network)
48
In an PON, where does the fiber cable connect to?
| (This is about FTTP) (PON = Passive Optical Network)
an OLT (Optical Line Terminal)
| The OLT is located in a street cabinet
49
In a PON, what happens after the fiber cable connects to an OLT?
## Footnote
(This is about FTTP) (PON = Passive Optical Network) (OLT = Optical Line Terminal)
Splitters direct subscriber traffic to ONTs at their premises
50
Meaning of ONT?
Optical Network Terminal
51
What do ONTs in a PON do?
| (This is about FTTP) (PON = Passive Optical Network)
Converts the optical signal to an electrical one
## Footnote
The optical signals carried by fiber optic cables are converted into electrical signals by the ONT to be used by the customer's devices
52
How is an ONT in a PON connected to the customer's router?
| (This is about FTTP) (PON = Passive Optical Network)
RJ45 copper wire patch cord
53
What identity do IP addresses contain?
Identity of network & a host within that network
| MAC addresses only identify a hardware port
54
What do firewalls do?
Filters allowed & denied hosts & protocols
55
Meaning of ACL?
Access Control List
56
What is an ACL?
The firewall's configured rules
57
What do ACLs list?
Network addresses, protocol types, & traffic permissions
58
What do networking hardware do?
Forwards data & connects devices
| i.e. routers, switches, patch panels, NICs, SDN, etc.
59
Meaning of NIC?
Network Interface Card
60
Purpose of NICs?
Allow devices to connect to Ethernet networks
61
What standard do most PC MOBO NICs support?
1000BASE-T Ethernet
| NICs may also support other types of Ethernet, like fiber optic
62
Why may NICs have multiple ports of the same type?
To bond for a higher-speed link
## Footnote
i.e. 4 gigabit Ethernet ports could be bonded to give a nominal lnk speed of 4Gbps
63
What kind of addresses do NICs have?
MAC addresses
64
Meaning of MAC?
Media Access Control
65
Where is the destination & source MAC address placed in Ethernet frames?
Header
66
What does a MAC address consist of?
48-bit hexadecimal number
## Footnote
MAC addresses can be writen with color or hyphen separators or no separators at all (i.e. `00 : 60 : 8c : 12 : 3a : bc` or `00608c123abc`)
67
How many values does the hexadecimal numbering system have?
16
68
What are the hexadecimal values?
0-9 & A-F
69
What does each Hexadecimal digit represent?
4 bits
## Footnote
So hex number "60" = 01100000 (96)
70
What are computers in a office setup typically connected to?
Wall ports linked to a patch panel
71
What is the rear of a patch panel used for?
Terminate wall cables to IDC punchdown blocks
| IDC = Insulation Displacement Connector
72
What does the front of a patch panel have?
Pre-wired RJ45 ports to connect to a switch
73
What cable is used to connect a port on a patch panel to a switch?
Patch cord
74
What were hubs used for?
Implementing the 10BASE-T & 100BASE-T Ethernet cabling designs
| aka "Star topology"
75
What is the 10BASE-T & 100BASE-T Ethernet cabling design referred to as?
Star topology
| This is because each end system is cabled to a concentrator (the hub)
76
How does a hub work?
Repeats incoming data from one port to all the other ports
| Each connected device receives & processes it, even if it's not for them
77
What is a collision domain?
Network segment where devices contend for a shared communication channel
| This can lead to collisions which can slow down network performance
78
When do devices connected to a hub ignore received frames?
When frames don't match its MAC address
79
What happens when a collision occurs in a hub?
| The more computers there are, the more collisions
All devices must wait a random period of time before trying again
| This random backoff period help reduce the likelihood of collisions happ
## Footnote
The random backoff reduces collision recurrence.
80
What does it mean that communication in hubs are half-duplex?
A computer can send or receive, but not at the same time
81
Why are hubs practically obselete?
Thye aren't compatible with Gigabit Ethernet
## Footnote
Hubs are typically only used in niche cases, often to support older equipment that needs to remain operational.
82
How do Switches differ from hubs?
Forwarding frames to the destination MAC address
| Rather than broadcasting frames to all devices
83
How are switches able to route frames?
By decoding frames to identify the source & destination MAC addresses
## Footnote
Each switch port is a separate collision domain, eliminating contention
84
What does it mean for devices on a switch to have full-duplex?
Devices can send & receive simultaneously at the full speed
| The full speed is dependent on the network cabling & NIC
85
What happens when a switch encounters a new source MAC address?
It records it in its MAC address table
86
What happens if a switch needs to forward a frame to an unknown destination MAC address?
It broacasts the frame to all ports except the one it arrived on
| This process is known as ***flooding***
87
How do unmanaged switches differ from managed switches?
Functioning without requiring any configuration
## Footnote
Plug it in, connect hosts, and it sets up Ethernet connections automatically
88
What type of switch is embedded in most SOHO router/modems?
Unmanaged switch
## Footnote
Some older SOHO routers use LAN interfaces as hubs, limiting speed to below 1Gbps
89
How do managed switches differ from unmanaged switches
Having additional functonality for configuration
| A managed switch will work as an unmanaged switch out of the box
90
How do admins manage a managed switch's settings?
Via management port
91
How many ports do typical workgroup switches come with?
24 or 48 ports
92
What does it mean when switches have uplink ports?
They can connect to other switches
93
How do modular switches work?
Provide power & a backplane to link multiple switches
## Footnote
This enables the provisioning of hundreds of access ports via a single compact appliance
94
What interface is used to configure managed switches?
Web or Command-Line interface
95
Meaning of PoE?
Power over Ethernet
96
What is PoE?
A means of supplying power from a switch port to a Powered Device (PD)
| A powered device lie a VoIP handset, camera, AP, etc.
97
3 IEEE standards PoE is defined in?
- 802.3af
- 802.3at
- 802.3bt
98
How much power can 802.3af deliver to devices?
up to 13W
99
What is the max power delivery of 802.3af?
15.4W
100
Why can't 802.3af supply 15.4W rather than 13W to devices?
Due to voltage drop over the length of the cable
101
How much power can 802.3at deliver to devices?
Up to 25W
102
What is 802.3at aka?
PoE+
103
What is 802.3bt aka?
PoE++ or 4PPoE
104
How much power can 802.3bt deliver to devices?
- Up to 51W (Type 3)
- Up to 73W (Type 4)
105
What happens when a device connects to a PoE switch?
PoE switch detects if the device supports PoE
106
What happens if a PoE switch detects a PoE device?
Determines device's power consumption & sets supply voltage level
107
What happens if a PoE switch detects a non-PoE device?
It doesn't supply power over the port
| Therefore, not damaging non-PoE devices
108
What can you use if a switch doesn't support PoE?
Power injector
## Footnote
One port on the injector connects to the switch port. The other port connects to the device
109
What is a power injector aka?
midspan
110
What is the max cable length when using a power injector?
100m
| This ensures optimal power delivery & network performance
111
What transmission media do wireless technologies use?
Radio waves
112
How do radio systems transfer signals?
## Footnote
Radio systems like AM/FM Radio broadcast, Two-way radios, Cellular networks, Wi-Fi, Satellite communication, etc.
Using transmission & reception antennas tuned to a specific frequency
113
What standards are most WLANs based on?
IEEE 802.11 standards
114
What is 802.11 aka?
Wi-Fi
115
What is "infrastructure mode" in wireless networking?
802.11 network framework where devices communicate with each other via one or more APs
| This means the devices connect to the network via an AP
116
Meaning of AP?
Access Point
117
What does each AP create in wireless infrastructure mode?
BSS (Basic Service Set)
118
What is a BSS in wireless infrastructure mode?
| (Basic Service Set)
Wireless network formed around an AP
119
What is a BSSID in wireless infrastructure mode?
MAC address of the AP's radio
## Footnote
i.e. In an office with two access points, "Office_WiFi_1" has a BSSID of "00:11:22:33:44:55," and "Office_WiFi_2" has a BSSID of "66:77:88:99:AA:BB." These BSSIDs uniquely identify the Basic Service Sets (BSS) created by each access point.
120
What is the BSSID in wireless infrastructure used for?
To uniquely identiy the BSS
## Footnote
i.e. In an office with two access points, "Office_WiFi_1" has a BSSID of "00:11:22:33:44:55," and "Office_WiFi_2" has a BSSID of "66:77:88:99:AA:BB." These BSSIDs uniquely identify the Basic Service Sets (BSS) created by each access point.
121
What else can an AP do besides creating a wireless-only network?
| Wireless-only network = infrastructure mode in Wi-Fi networking
Bridge wireless stations with wired networks
| "stations" means devices connected to the wireless network
122
What is the "distribution system" (DS) in wireless networking?
Wired portion of the network
123
How is an AP joined to a network?
Via Ethernet switch
## Footnote
An enterprise network is likely to use PoE to power the AP over the data cabling
124
Meaning of SDN?
Software-Defined Networking
125
What is SDN?
Model that automates network provisioning & deprovisioning in the cloud
## Footnote
Cloud network provisioning involves configuring resources like IP addresses, virtual networks, security policies, and connectivity for deploying applications or services. network deprovisioning involves the removal or decommissioning of network resources that are no longer needed.
126
What layers does SDN devide network functions into?
- Application Layer
- Control Layer
- Infrastructure Layer
127
What are the functions of the Application Layer in SDN?
Applies business logic to prioritize, secure, & direct traffic
128
What are the functions of the Infrastructure Layer in SDN?
Contains devices that handle forwarding of traffic
## Footnote
The devices can be physical or virtual. "forwarding" here refers to switching & routing
129
What is the control plane of the control layer in SDN implemented by?
A virtual device referred to as the "SDN controller"
130
What does each layer in SDN expose?
API that can be automated by scripts that calls functions in adjacent layers
| API = Application Programming Interface
## Footnote
By adjacent layers, it means the layers above or below it.
131
What is the "northbound" API (or service interface) in SDN?
| API = Application Programming Interface
The interface between SDN apps & the SDN controller
132
What is the "southbound" API in SDN?
| API = Application Programming Interface
The interface between the SDN controller & infrastructure devices
133
How do NICs process electrical/light signals as digital data?
Ethernet’s data link layer divides signals into frames
| Frames have a consistent format defined by Ethernet standards
