Network + E2

802.11g

2.4 GHZ 54 Mbps 100 m

802.11b

2.4 GHz 11 Mbps 100 m

802.11n

2.4 and 5 GHZ 600 Mbps 70m indoor 100m outdoor

802.11a

5 GHZ 54 Mbps 50 m

PPP (Point-to-Point Protocol)

A Layer 2 communications protocol that enables a workstation to connect to a server using a serial connection such as dial-up or DSL.

PRAT (Passive Reader Active Tag)

A battery-powered tag actively transmits its credentials at regular time intervals. Battery-powered tags don't require such close proximity to function—the most sophisticated devices work up to 200 m away.

SDN controller (Software defined network)

A centralized approach to networking that removes most of the decision-making power from network devices and instead handles that responsibility at a software level.

spectrum analyzer

A device that can assess the quality of a wireless signal. Spectrum analysis is useful, for example, to ascertain where interference is greatest.

Tone locator (or probe)

A device that emits a tone when it detects electrical activity on a wire

media converter

A device that enables networks or segments using different media to interconnect and exchange signals.

Multiplexing

A form of transmission that allows multiple signals to travel simultaneously over one medium.To carry multiple signals, the medium's channel is logically separated into multiple smaller channels, or sub-channels. Many different types of multiplexing are available, and the type used in any given situation depends on what the media, transmission, and reception equipment can handle.

ESS

A group of access points connected to the same LAN. BSSes that belong to the same ESS share a special identifier, called an ESSID (extended service set identifier). Within an ESS, a client can associate with any one of many APs that use the same ESSID. This allows users to roam about a large office space without losing wireless network service. In practice, many networking professionals don't distinguish between the terms SSID and ESSID. They simply configure every access point in a group or LAN with the same SSID.

BSS

A group of nodes that share an access point. The identifier for this group of nodes is known as a BSSID (basic service set identifier).

TDM (time division multiplexing) (COPPER)

A multiplexing method in which the communication channel is divided into discrete time slots that are assigned to each node on a network.

CWDM (coarse wavelength division multiplexing)

A multiplexing technique used over single-mode or multimode fiber-optic cable in which each signal is assigned a different wavelength for its carrier wave. In CWDM, channels are spaced more widely apart than in DWDM to allow for the use of cheaper transceiver equipment.

LaaS

A service model in which hardware services are provided virtually, including network infrastructure devices such as virtual servers.

Toner generator (or toner)

A small, electronic device that issues a signal on a wire

DSSS (Direct Sequence Spread Spectrum)

A transmission technique in which a signal's bits are distributed over an entire frequency band at once. Each bit is coded so that the receiver can reassemble the original signal upon receiving the bits.

Cable performance tester

A troubleshooting tool that tests cables for continuity, but can also measure cross talk, attenuation, and impedance; identify the location of faults; and store or print cable testing results.

site-to-site VPN

A type of VPN in which VPN gateways at multiple sites encrypt and encapsulate data to exchange over tunnels with other VPN gateways. Meanwhile, clients, servers, and other hosts on a siteto- site VPN communicate with the VPN gateway.

client-to-site VPN

A type of VPN in which clients, servers, and other hosts establish tunnels with a private network using a VPN gateway at the edge of the private network.

EMI (electromagnetic interference)

A type of interference that may be caused by motors, power lines, televisions, copiers, fluorescent lights, or other sources of electrical activity.

FDM (frequency division multiplexing) (COPPER)

A type of multiplexing that assigns a unique frequency band to each communications subchannel. Signals are modulated with different carrier frequencies, then multiplexed to simultaneously travel over a single channel.

ad hoc

A type of wireless LAN in which stations communicate directly with each other (rather than using an access point).

infrastructure

A type of wireless network in which stations communicate through an access point and not directly with each other.

FHSS (Frequency Hopping Spread Spectrum)

A wireless signaling technique in which a signal jumps between several different frequencies within a band in a synchronization pattern known to the channel's receiver and transmitter.

Passive scanning

A wireless-enabled computer listens on all channels within its frequency range for a special signal, known as a beacon frame, issued periodically from an AP. The beacon frame contains information that a wireless node requires to associate itself with the AP, including the network's transmission rate and the SSID (service set identifier), a unique character string used to identify an access point.

ARAT (Active Reader Active Tag)

An active reader interacts with a battery-powered tag.

Evil twin

An exploit in which a rogue access point masquerades as a legitimate access point, using the same SSID and potentially other identical settings.

Multimeter

An instrument for measuring the properties of an electrical circuit.

RG-59 coaxial cable

An older and thinner coaxial cable once used for cable TV.

SaaS

Applications are provided through an online user interface and are compatible with a variety of devices and operating systems. Online email services such as Gmail and Yahoo! are good examples of SaaS, as are CRM (customer relationship management) apps, such as Salesforce and Zoho.

SSL/TL

Are both methods of encrypting TCP/IP transmissions—including web pages and data entered into web forms—en route between the client and server using public key encryption technology. The two protocols can work side by side and are widely known as SSL/TLS or TLS/SSL. All browsers today (for example, Google Chrome, Mozilla Firefox, Apple's Safari, Microsoft Edge, and Internet Explorer) support SSL/TLS to create secure transmissions of HTTP sessions.

STDM (statistical time division multiplexing) (COPPER)

Assigns time slots to nodes (similar to TDM), but then adjusts these slots according to priority and need. This approach uses all slots rather than leaving some unused, which maximizes available bandwidth on a network.

Cat 6a

Bandwidth 500 hz

Cat 5e

Cat 5e or higher wiring, which is the minimum required to support Gigabit Ethernet.

Cat 6

Category 6 wire; TIA/EIA standard for UTP wiring that can operate at up to 10 Gbps. Bandwidth 250 hz

RG-6 Cable

Coaxial Cable used for connecting homes to cable networks. Larger conductor and higher frequencies than RG-59.

Hypervisor

Creates and manages a VM, and manages resource allocation and sharing between a host and any of its guest VMs.

FEXT

Crosstalk measured at the far end of the cable from the signal source

NEXT

Crosstalk that occurs between wire pairs near the source of a signal

Wifi uses what?

DSSS

Zigbee uses what?

DSSS

Bluetooth uses what?

FHSS

802.11ac

Gigabit Ethernet capabilities

IPsec creates secure connections in five steps:

IPsec initiation Key management: IKE ISAKMP Security negotiations Data transfer:After parameters and encryption techniques are agreed upon, a secure channel is created, which can be used for secure transmissions until the channel is broken. Data is encrypted and then transmitted. Either AH (authentication header) encryption or ESP (Encapsulating Security Payload) encryption may be used. Both types of encryption provide authentication of the IP packet's data payload through public key techniques. In addition, ESP encrypts the entire IP packet for added security. Termination: IPsec requires regular reestablishment of a connection to minimize the opportunity for interference. The connection can be renegotiated and reestablished before the current session times out in order to maintain communication.

Channel Bonding

In the context of 802.11n and 802.11ac wireless technology, the combination of two or more adjacent 20-MHz frequency bands to create one 40-, 60-, 80-, or 120-MHz channel.

Association

In the context of wireless networking, the communication that occurs between a wireless client and an access point enabling the client to connect to the network via that access point.

Ipsec

Internet Protocol Security. Used to encrypt traffic on the wire and can operate in both tunnel mode and transport mode. It uses tunnel mode for VPN traffic. IPsec is built into IPv6, but can also work with IPv4 and it includes both AH and ESP. AH provides authentication and integrity, and ESP provides confidentiality, integrity, and authentication. IPsec uses port 500 for IKE with VPN connections.

WDM (wavelength division multiplexing) (Fiber Optics)

Is a technology used with fiber-optic cable, which enables one fiber-optic connection to carry multiple light signals simultaneously.

Attenuation

Loss of power in a signal as it travels from the sending device to the receiving device

Fast Ethernet

Networks, which have a maximum speed of 100 Mbps, one pair sends data, another pair receives data, and the other two pairs are not used for data transmission.

Diffraction

Occurs when an object causes a wave to change direction and bend around it

VPN protocols

PPTP (Point-to-Point Tunneling Protocol) GRE (Generic Routing Encapsulation) L2TP (Layer 2 Tunneling Protocol) OpenVPN IKEv2

Jitter

Packets experience varying amounts of delay, they can arrive out of order

PaaS

Provides cloud customers with an easy-to-configure operating system and on-demand computing capabilities. Compare to IaaS and SaaS.

MIMO (multiple input-multiple output)

Related to MIMO, MU-MIMO is an even newer technology implemented by 802.11ac Wave 2 products that allows multiple antennas to service multiple clients simultaneously. This feature reduces congestion and thereby contributes to even faster data transmission. As with MIMO, however, a MU-MIMO access point can only be used at full capacity when the client devices also support MU-MIMO technology.

Mesh

Several access points work as peer devices on the same network

Duplex or Full Duplex

Signals are free to travel in both directions over a medium simultaneously. As an analogy, talking on the telephone is a full-duplex transmission because both parties in the conversation can speak at the same time. Modern NICs use full-duplex by default.

Half Duplex

Signals may travel in both directions over a medium but in only one direction at a time. For example, an apartment building's intercom system might be half-duplex if only one person can speak at a time.

Simplex

Signals may travel in only one direction, and is sometimes called one-way, or unidirectional, communication. Broadcast radio and garage door openers are examples of simplex transmissions.

WiFi analyzer

Software that can evaluate Wi-Fi network availability as well as help optimize Wi-Fi signal settings or help identify Wi-Fi security threats. Identifying the wireless channels being used nearby helps you optimize the wireless channel utilization in your vicinity.

War driving

The act of driving around an area while running a laptop configured to detect and capture wireless data transmissions.

Virtualization

The emulation of all or part of a computer or network.

RTT (Round Trip Time)

The length of time it takes for a packet to go from sender to receiver, then back from receiver to sender. A way to measure latency.

Scanning

The process by which a wireless station finds an access point.

Active scanning

The wireless client takes the initiative

Latency

Time it takes for a bit to travel from its sender to its receiver.

host-to-host VPN

Two computers create a VPN tunnel directly between them. Both computers must have the appropriate software installed, and they don't serve as a gateway to other hosts on their respective networks.

DWDM (Dense Wavelength Division Multiplexing)

Used on most modern fiber-optic networks Extraordinary capacity Typically used on high-bandwidth or long-distance WAN links

Ant+ uses what?

Uses neither DSSS or FHSS

ARPT (Active Reader Passive Tag)

When prompted by an active reader, a passive tag pulls power from the reader's radio waves to power its transmission. These tags only work within a few centimeters of the reader.

Gigabit Ethernet

With a speed of at least 1000 Mbps, use all four pairs for both sending and receiving. You'll learn more about Ethernet standards later in this chapter.

RTS/CTS

a source node issues an RTS signal to the access point requesting the exclusive opportunity to transmit. If the access point agrees by responding with a CTS signal, the access point temporarily suspends communication with all nodes in its range and waits for the source node to complete its transmission. When used, RTS/CTS decreases network efficiency. However, it can be worthwhile when transmitting large packets.

OPM

also called a light meter, measures the amount of light power transmitted on a fiber-optic line.

Terminal Emulation

also called remote virtual computing, allows a user on one computer, called the client, to control another computer, called the host or server, across a network connection. Examples of command-line software that can provide terminal emulation include Telnet and SSH, and some GUI-based software examples are Remote Desktop for Windows, join.me, VNC, and TeamViewer

alien cross talk

cross-talk that occurs between two cables

GRE (Generic Routing Encapsulation)

developed by Cisco, is a Layer 3 protocol used to transmit PPP, IP, and other kinds of messages through a tunnel. Like L2TP, GRE is used in conjunction with IPsec to increase the security of the transmissions.

RDP

is a Microsoft proprietary protocol used by Windows Remote Desktop and Remote Assistance client/server utilities to connect to and control a remote computer

L2TP (Layer 2 Tunneling Protocol)

is a VPN tunneling protocol based on technology developed by Cisco and standardized by the IETF.

VPN

is a network connection encrypted from end to end that creates a private connection to a remote network. A VPN is sometimes referred to as a tunnel.

PPTP (Point-to-Point Tunneling Protocol)

is an older, Layer 2 protocol developed by Microsoft that encapsulates VPN data frames. It uses TCP segments at the Transport layer. PPTP supports the encryption, authentication, and access services provided by the VPN server; however, PPTP itself is outdated and is no longer considered secure.

Open VPN

is an open-source VPN protocol that uses a custom security protocol called OpenSSL for encryption. OpenVPN has the ability to cross many firewalls where IPsec might be blocked. It is both highly secure and highly configurable.

CSMA/CA

minimizes the potential for collisions, but cannot detect the occurrence of a collision and so cannot take steps to recover from the collisions that do occur.

Crosstalk

occurs when the signals of one wire affect the signals on an adjacent wire

Continuity

that is, whether it is carrying a signal to its destination. Tools used to test the continuity of the cable might be called cable checkers, continuity testers, or cable testers.

Refraction

the bending of a wave as it enters a new medium at an angle

IPsec can be used with any type of TCP/IP transmission and operates in two modes:

transport mode—Connects two hosts. tunnel mode—Runs on routers or other connectivity devices in the context of VPNs.

VNC

uses the cross-platform protocol RFB (remote frame buffer) to remotely control a workstation or server. VNC is slower than Remote Desktop and requires more network bandwidth.

IKEv2

which as you learned earlier is a component of the IPsec protocol suite, offers fast throughput and good stability when moving between wireless hotspots. It's compatible with a wide variety of devices and is often recommended by VPN providers as the most secure option among the VPN protocols they support.