Different Wide Area Networks

ISDN (Integrated Services Digital Network)

ISDN is circuit switched network that enables digital transmission over telephone lines. It allows data, valce; video transmissions aver a single line and multiple devices can use the same communication line. ISDN is widely used for high speed Internet access in most countries:

ISDN access is offered as Basic Rate Interface (BRI) & Primary Rate interface (PRI), ISDN offers speed in increments of 64 Kbps. BRI offers 128 Kbps delivered over standard copper telephone lines. With a payload of 144 Kbps, it is broken into two 64 Kbps (bearer channels, referred to as channel “B”) and one 16 Kbps ignating channel (bearer channels, referred to as channel “D”). In short, BRI s 28-1D. PRI is delivered on T1 carriers as 238 channels (64 Kbps each) and 1D Channel (64 Kbps for signaling in North America. However, the configuration varies across locations as displayed below:

Region	ISDN PRI Configuration	Speed
North America	23B + 1D	1.544 Mbps (T1)
Japan	23B + 1D	1.544 Mbps (T1)
Europe	30B + 1D	2.048 Mbps (E1)
Australia	30B + 1D	2.048 Mbps (E1)
India	30B + 1D	2.048 Mbps (E1)

DSL

Digital subscriber line is a family of technologies that provide internet access by tranamiting digital data over telephone network. This is achieved by using different frequencies for voice and data.

The service is offered by installing a DSLAM (Digital Subscriber Line Access Multiplesoritat telephone exchanges) and a DSL filter (at customer’s premises to split voice and data thereby enabling simultaneous transmission of voice and data Since multiple signals are sent over pairs of wires at different frequencies, this us categorized as broadband: DSL uses PPPoE (Point-to-Point Protocol Over Ethernet)

DSL used today widely represents ADSL a vartant that provide varying speeds in the range of 128 Kbps to over 40 Mbps downstream depending on the technology line conditions and service-level implementations

Following is a summary of xDSL standards:

Techonology	Rate (kbit/s)	Rate (kbyte/s)
IDSL (dual ISDN + 16 kbit/s data channels)	144 kbit/s	18 kB/s
HDSL	1544 kbit/s	193 kB/s
MSDSL	2000 kbit/s	250 kB/s
SDSL	2320 kbit/s	290 kB/s
SHDSL (ITU G. 991.2)	5690 kbit/s	711 kB/s
ADSL (G.lite)	1536/512 kbit/s	192/64 kB/s
ADSL (G.DMT)	8192/1024 kbit/s	1024/128 kB/s
ADSL2	12288/1440 kbit/s	1536/180 kB/s
ADSL2+	24576/3584 kbit/s	3072/448 kB/s
UDSL	200000 kbit/s	25000 kB/s
VDSL (ITU G. 993.1)	52000 kbit/s	7000 kB/s
VDSL (ITU G. 993.2)	100000 kbit/s	13000 kB/s

DSL is offered by vendors with a variety of options and sometimes with usage restrictions based on quota and/or bandwidth.

For example, an ISP may offer a download speed of 2 Mbps and configure it in a way that it steps down automatically to 512 Kbps or lower once you reach a download limit of 10 GB. However, this depends on the plan taken from an ISP.

Note: Your facilitator can demonstrate to set up a DSL connection only if a DSL router and an active internet connection is available. You need an active DSL connection from an ISP, a DSL Modem and a computer to use DSL.

1. Connect the DSL Modem to the splitter
2. Turn on the DSL Modem
3. Open the web browser, type the IP address of the Router and login
4. View DSL Connection properties (Use the Router Product Manual)

Cable Internet Access

Cable Internet access is a form of broadband communication that uses cable television infrastructure. Like DSL, cable Internet access is provided through co axial or fiber optic cables from the ISP to customer’s premises. Unlike DSL that provides dedicated bandwidth, cable Internet users share the available bandwidth.

Cable Internet access is multiplexed at ISP and splitters are used to provide signals to TV and Cable MODEM. Many cable TV providers often bundle Internet access along with cable TV channel subscriptions. Depending on the provider, varying speeds are offered in the range of 1 Mbps to over 400 Mbps.

PPPOE

PPPoE or Point-to-Point Protocol over Ethernet is a protocol that is commonly used in broadband services such as DSL & Cable Modems. PPPOE encapsulates PPP frames within Ethernet Frames.

Wireless WAN

Wireless Internet access is used where wired connectivity is not possible or for remote locations: Wireless WAN uses technologies such as LTE, WIMAX, GSM, CDMA, etc. for providing connectivity.

WIMAX

WIMAX or Worldwide Interoperability for Microwave Access is a wireless communication standard used for providing Internet Access to fixed stations. WIMAX is used where wired Internet access such as DSL or Cable is not possible or available.

As compared to other wireless technologies, WIMAX is preferred as it economically viable and easier to implement. WIMAX can provide speeds of 30 to 40 Mbps with current trend at around 1 Gbps; however, the actual speed offered depends on the ISP.

PPPOE

PPPoE or Point-to-Point Protocol over Ethernet is a protocol that is commonly used in broadband services such as DSL & Cable Modems. PPPoE encapsulates PPP frames within Ethernet Frames.

X.25

x.25 is a packet switching technology used in Wide Area Networks. In X.25, a Packet Assembler/ Dis-assembler (PAD) assembles and disassembles packets during transmission.

An X.25 WAN consists of packet-switching exchange (PSE) nodes as the networking hardware, and leased lines, telephone service connections or 15DN connections as the physical links. X.25 is a family of protocols that was popular during the 1980s with telecommunications companies and in financial transaction systems such as automated teller machines, X.25 supports speeds up to 2 MB.

Frame Relay

Frame relay is a packet switching technology originally designed for ISDN infrastructure but also used in many other network interfaces. Though X.25 provides quality of service and error-free delivery, Frame Relay relays data as quickly as possible over low error networks and hence supersedes X.25.

ATM

Asynchronous Transfer Mode or ATM is a packet switching technology using fixed cell size of 53 bytes between end points over a virtual circuit. ATM uses asynchronous TDM and is designed to handle voice, data and video signals.

FDDI

Fiber Distributed Data Interface or FDDI is a token ring based network using optical fiber. FDDI provides speed up to 100 Mbps and distance up to 200 kilometers. FDDI operates through two rings, one acting as a backup in case the primary one fails.

SONET

Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams over optical fiber using lasers light from light-emitting diodes (LEDs). Optical Carrier transmission rates are a standardized set of specifications of transmission bandwidth for digital signals that can be carried on SONET. Base Unit is 51.84 Mbps and offered in multiples of base units (Table below).

SONET OCx	Payload (Mbit/s)	Line rate(Mbit/s)
OC-1	50112	51840
OC-3	150336	155520
OC-12	601344	622080
OC-24	1202688	1244160
OC-48	2405376	2488320
OC-192	9621504	9953280
OC-768	38486016	39813120