chapter 5 (WAN technologies,...Internet access technologies)

What type of technology is Satellite Internet connections?

A line-of-sight wireless technology, and the installation configuration must be precise.

ISDN DSL (IDSL):

A symmetric type of DSL commonly used in environments in which SDSL and ADSL are unavailable, No support for analog phones [upload spedd 144Kbps] [download speed 144kbps]

Rate-adaptive DSL(RADSL):

A variation on ADSL, can modify its transmission speeds based on signal quality. Supports line sharing [upload speed 1Mbps] [download speed 7Mbps]

Channel Service Unit/Data Service Unit (CSU/DSU)

Acts as a translator between the LAN data format and the WAN data format. Necessary because the technologies used on WAN links are different from those used on LANs. Changes the signal from one digital format to another.

Very high bit rate DSL (VHDSL or VDSL):

An asymmetric version of DSL and, can share a telephone line. Supports high-bandwidth applications such as VoIP and HDTV. Can achieve data rates up to approximately 10Mbps, fastest available form of DSL. Uses fiber optic cabling to achieve high speeds. [upload speed 1.6Mbps] [download speed 13Mbps]

what two types of systems exist for DSL?

Asymmetric digital subscriber line (ADSL) high-rate digital subscriber line (HDSL)

Dial-up access account through an ISP:

Can easily be obtained by contacting one of the many local regional, or national ISPs. Most ISPs offer a range of plans normally priced based on the amount of time the user is allowed to spend online. Maxium access is 56Kbps

Downsides of Satellite Internet access?

Cost High latency

Internet access through a phone system requires two things:

Dial-up modem: Dial-up access account through an ISP

Cable broadband:

Internet access that is always on internet access method, available in areas that have digital cable. Inexpensive and reliable. Don't restrict how much use is made of the access, do control the speed. Connectivity is achieved by using a CABLE MODEM

Smart jack/network interface Device(NID)

Loopback feature Signal amplification Surge Protection Remote alarms

Hotspots

Offer internet access for mobile network devices such as laptops, handheld computers, and cell phones in airports, coffee shops, conference rooms, and so on. Created using one or many many wireless access points near the hotspot location.

Public Switched Telephone Network(PTSN):

Often considered Plain Old Telephone System(POTS), is the entire collection of interconnected telephone wires throughout the world. Include all the equipment that goes into connecting two points, such as cable, the networking equipment, and the telephone exchanges. The modern version of it is largely digital, with analog connections existing primarly between homes and local phone exchanges. Using PTSN is a popular choice for establishing WAN, but the drawback is transfer speeds(56 Kbps) and 128Kbps with an ISDN connections.

What are the two types of Broadband Internet satellite services?

One-way two-way

Positive features of Satellite Access?

Portability

Asymmetric digital subscriber line (ADSL):

Provides a high data rate in only one direction. Enables fast download speeds but significantly slower upload speeds. Designed to work with existing analog telephone service (POTS) service. WELL SUITED FOR HOME USE INTERNET ACCESS. Most common, Uses one channel for POTS, responsible for analog traffic. Second channel provides upload access, third channel used for downloads. [upload speed 1Mbps] [download speed 3Mbps]

High-rate digital subscriber line (HDSL)

Provides bidirectional high-data-rate service that can accommodate services such as videoconferencing that require high data rates in both directions [upload speed 768] [download speed 768]

Two-way Satellite system

Provides data paths for both upstream and downstream data. Uses a satellite card and a satellite dish installed at the end user's site; bidirectional communication occurs directly between the end user's node and the satellite.

Surge protection

Provides protection from environmental situations, such as electrical surges.

What aspects of Satellite Internet should you be aware of ?

Rain Fade Latency Line-of-sight

Rain Fade

Refers to signal loss due to moisture interference. The general rule is that the smaller the dish, the more susceptible it is to rain fade.

Latency

Refers to the time lapse between sending or requesting information and the time it takes to return.

One-way Satellite system

Requires a satellite card and a satellite dish installed at the end user's site. Works by sending outgoing requests on one link using a phone line, with inbound traffic returning on the satellite link

Service Set Identifier

SSID

Signal amplification

Smart jack can amplify signals. Similar to that of the function of repeaters in an Ethernet network.

High bit rate DSL (HDSL):

Symmetric technology that offers identical transmission rates in both directions. HDSL does not allow line sharing with analog phones. [upload speed 768Kbps] [download speed 768kbps]

Line-of-sight

The path between the satellite dish and the satellite should be as unobstructed as possible.

Digital subscriber line (DSL)

an internet access method that uses a standard phone line to provide high-speed Internet access.

Loopback feature

built into the smart jack. It is used for testing purposes. Enables remote testing so that the technicians do not always need to be called to visit the local network to isolate problems

Demarcation point

connection point between the operators part of the network and the customer's portion of the network. Distinguishes the portion of the network that the customer is responsible for from the section the owner is responsible for. The point at which the ISP places its services in your network. The ISP term for where their facilities or wires end and where yours begin.

Dial-up modem:

devices that convert the digital signals generated by a computer system into analog signals that can travel across a phone line.

Termination points

endpoints that stop the signal and prevent it from living beyond its needed existence.

Propagation time

how long it takes the signal to travel back and forth from the satellite. This time time is long, therefore is an important consideration for business applications.

Symmetric DSL (SDSL):

offers the same speeds for uploads and downloads, making it most suitable for business applications such as web hosting, intranets, and e-commerce. Not widely used in home/small business environments, cannot share a phone line. [Upload Speed 1.5Mbps] [Download Speed 1.5Mbps]

broadband

often refers to high speed Internet access. Both DSL and cable modems are common broadband Internet technologies.

Satellite Internet Access

provides a viable Internet access solution for those who cannot get other methods of broadband. Offers an always-on connection, download speeds faster than old-dialup.

Dial-up

same line used for a household phone is used for dial-up access, it is called the plain old telephone system (POTS) method of access.

Termination

the process to connect the network cable to the wall jack, plug, or patch panel. A straightforward process. Quickly see if the wiring and termination worked if the LED on connected network card is lit. Can also ping other devices on the network if all works.

Latency

the time it takes for the signal to travel back and forth from the satellite.

Remote alarms

typically include alarms that allows the owners to identify if something goes wrong with the smart jack and therefore the connections at the demarcation point.

One of the biggest disadvantages of Cable access

you share the available bandwidth with everyone else in your cable area. During peak time, performance of a cable link might be poorer than in low-use periods.