• Repeaters operate in the Physical layer of the OSI model-no means to interpret the data they retransmit.
• one input and output port - receiving and repeating a single data stream.
• repeater allows you to extend a network inexpensively.

• Hub is a repeater with more than one output port.
• Hub accepts signals from aa transmitting node and repeats those signals to all other connected node in a broadcast fashion.
• Because of their limited features and the fact that they merely repeat signals within a single collision domain, hubs were replaced by routers and switches.

• Bridges are device that connect two network segments by analysing incoming frames and making decisions about where to direct them based on each frame's MAC address.
• They operate at the Date Link layer of the OSI model

• Switches are connectivity devices that subdivide a network into smaller logical pieces, or segments.
• Traditional switches operate at the data link layer of OSI model.
• modern switches can operate at Layer 3 or even Layer 4.
  Because they have multiple port, switches can make better use limited bandwidth and prove more cost efficient than bridges.

• router is multiport connectivity device that directs data between nodes on a network.
• Routers can integrate LANs and WANs running at different transmission speeds and using a variety of protocols.
• Layer 3 (network layer) of OSI model.

• Wireless Access Point (WAP) that Allows a Wi-Fi compliant device to connect to a wired network.
• mobility.
• WAP is differentiated from a hotspot, which is the physical location where Wi-Fi access to WLAN is avaible.

• Stand for Modulation and Demodulation.
• Convert either digital signal to analog signal (modulation) and analog signal to digital signal (demodulation).

• a network interface card (NIC) is a hardware component, typically a circuit board or chip, which is installed on a computer so that it can connect to a network.
• NICs are designed for use with either wired or wireless networks.
  1) On-Board NICs, via an expansion slot or peripheral bus
  2) wireless NICs, which contain antennas to send and receive signals wirelessly.

• Management and development of initernet standards.

• develops, updates , and maintains internet and TCP/IP protocols.

• coordinates IP address allocation and management of domain names.

• manages IP address allocation, domain name management, and protocol
  identifiers for ICANN.

• dedicated to advancing technological innovation and creating standard in a wide area of industries including networking.

• standards related to electrical wiring, connectors and network racks.

• standard for radio equipment , cellular towers, voice over IP(VoIP) devices, and satellite communications.

Standard for video compression, internet protocol Television (IPTV), and broadband communications.

• Open standards encourage interoperability, competition and innovation.

• Standard organization are usually vendor-neutral, non-profit organizations established to develop and promote the concept of open standards.

Pure Digital Signal

• conducts electrical signals very well but it has its
  limitation
• data travels on copper cables as small pulses of
  electrical voltage cause it easily distorted by outside
  noise and signal attenuation
• cable type with shielding or twisting of the pairs of
  wires are designed to minimize signal degradation

Coaxial cable

• Used in Ethernet LANs
• Eight wires twisted into four color-coded pairs and then
  wound inside a cable jacket
• Colored pairs identify the wires for proper connection at
  the terminals

The separation of data and electrical power cabling must comply with safety codes.

Twisted-Pair

• Protects the signal form interference

Color-Coded Plastic insulation

• Electrically isolates wires form each other and indentifies each pair

Outer Jacket

• Protects the copper wire form physical damage

Typically a PVC jacket that
protects the fiber against abrasion moisture, and other contaminants
This outer jacket composition can vary depending on the cable
usage.

The core is actually the light
transmission element at the center of the optical fiber. This core is
typically silica or glass, Light pulses travel through the fiber core.

Made from slightly different
chemicals than those used to create the core. It tends to act like
a mirror by reflecting light back into the core of the fiber. This
keeps light in the core as it travels down the fiber

Surrounds the buffer, prevents the
fiber cable from being stretched when it is being pulled. The
material used is often the same material used to produce
bulletproof vests.

Commonly used with campus backbones for distance of several thousand meters

Suited for long distance application, but shorter than single mode

Commonly Used with LANs or distances of couple hundred meters within a campus network