Integrated services digital network

1. ISDN & DSL
Group Members:
Waliullah Panhwar
Tariq Kanher
Umair Saeed

2. Agenda
• ISDN
• DSL
– Introduction
– DSL Family

3. ISDN

4. What is ISDN?
• ISDN stands for Integrated Services Digital Network.
• It is a design for a completely digital
telephone/telecommunications network.
• It is designed to carry voice, data, images, video, everything
you could ever need.
• It is also designed to provide a single interface (in terms of
both hardware and communication protocols) for hooking up
your phone, your fax machine, your computer, your
videophone, your video-on-demand system.

5. ISDN Benefits
• Carries a variety of user traffic, such as digital video,
data, and telephone network services, using the normal
phone circuit-switched network
• Offers much faster call setup than modems by using out-
of-band signaling (D channel)
– Often less than one second
• Provides a faster data transfer rate than modems by
using the 64-kbps bearer channel (B channel)
– Can combine multiple B channels to bandwidth of 128 kbps

6. ISDN Services

7. Voice Over Analog Network

8. Voice & Data Over Analog
Network

9. Analog & Digital Services

10. Integrated Digital Network

11. Integrated Service Digital
Network

12. Two Types of ISDN “Channels"
or Communication Paths
1. B-channel
2. D-channel

13. 1. B-channel
• The Bearer ("B") channel is a 64 kbps
channel which can be used for voice,
video, data, or multimedia calls.
• B-channels can be aggregated together for
even higher bandwidth applications.

14. 2. D-channel
• The Delta ("D") channel can be either a 16
kbps or 64 kbps channel used primarily for
communications (or "signaling") between
switching equipment in the ISDN network
and the ISDN equipment at your site.

15. ISDN Services Connections
1. Basic Rate Interface (BRI)
2. Primary Rate Interface (PRI)

16. 1. Basic Rate Interface (BRI)
• BRI is the ISDN service most people use to connect to the
Internet.
• An ISDN BRI connection supports two 64 kbps B-channels
and one 16 kbps D-channel over a standard phone line.
• BRI is often called "2B+D" referring to its two B-channels and
one D-channel.
• The D-channel on a BRI line can even support low-speed (9.6
kbps) X.25 data, however, this is not a very popular application
in the United States.

17. Basic Rate Interface

18. 2. Primary Rate Interface
(PRI)
• ISDN PRI service is used primarily by large
organizations with intensive communications
needs.
• An ISDN PRI connection supports 23 64 kbps B-
channels and one 64 kbps D-channel (or 23B+D)
over a high speed DS1 (or T-1) circuit.
• The European PRI configuration is slightly
different, supporting 30B+D.

19. Primary Rate Interface

20. ISDN Devices
• Terminal Adapter (TA) - Converter device that converts
standard electrical signals into the form used by ISDN - allows
non-ISDN devices to operate on an ISDN network.
• Terminal Equipment Type 1 (TE1) - Compatible with the
ISDN network. Example: Telephones, personal computers,
fax machine or videoconferencing machine.
• Terminal Equipment Type 2 (TE2) - Not compatible with the
ISDN network. Example: Analog phone or modem, requires a
TA (TE2 connects to TA).
• Network termination type 1 & 2 (NT1 and NT2) - A small
connection box that physically connects the customer site to
the Telco local loop, provides a four-wire connection to the
customer site and a two-wire connection to the network (PRI –
CSU/DSU).

21. Functional Grouping

22. ISDN Components and
Reference Points

23. ISDN Reference Points
• U - Two wire cable that connects the
customer’s equipment to the
telecommunications provider
• R - Point between non-ISDN equipment
(TE2) and the TA
• S - Four-wire cable from TE1 or TA to the
NT1 or NT2
• T - Point between NT1 and NT2

24. Reference Points

25. ISDN Layers

26. ISDN Layers for B & D
Channels

27. Pseudoternary Encoding

28. 2 Binary1 Quaternary
Encoding

29. BRI Frame

30. BRI Topology

31. PRI Frame

32. Bit Rates for Different
Applications

33. DSL

34. Digital Subscriber Line – DSL
• DSL technology provides high-speed,
broadband network connections to homes
and small businesses.
• DSL utilizes the same cabling used for
normal telephones, but it can offer higher
data rates through use of the digital
modem technology.

35. DSL
• DSL modems comprise the heart of this
technology and the lines themselves are
actually just plain telephone lines.
• It's possible for DSL subscribers to share
the same line for their digital and analog
traffic  play web + receive a call.

36. DSL Technology
• Speed
– DSL offers more than 100 times the network
performance of a traditional analog modem.
– the precise speed of a connection depends on
the variety of xDSL deployed.
– DSL is a distance-sensitive technology.

37. DSL Technology
• DSL works on the unused (high)
frequencies of the telephone line.
• DSL modems contain an internal signal
splitter that carries voice signals on the
usual low frequencies (from 0 up to 4kHz)
and data signals above that.
• This splitter, consequently, allows
simultaneous access to the line by the
telephone and the computer.

38. DSL Technology
• Access
– DSL service remains "on" all of the time.
– People should be aware that long-lived
connections like DSL can have security issues
 firewall.

39. DSL Technology
• Availability
– The technology used to implement DSL only
works over a limited physical distance. At the
maximum, DSL runs about 18,000 feet (3.5
miles or 5.5 kilometers) from a telephone
exchange.

40. DSL Technology
• Availability (cont.)
– To be eligible for DSL service, the phone line
involved must be "qualified."
– the home or business must lie within the
distance limitations of DSL (18,000 feet).
– This phone line must also possess sufficient
electrical quality characteristics.

41. DSL Availability of
Bandwidth
• The actual network bandwidth a customer
will receive from DSL in the home depends
on the span of their telephone wiring.
• The longer the line, the less bandwidth
DSL can support.
• Likewise, its thickness (wire gauge) can
affect performance.

42. DSL availability of bandwidth
Cable length Bandwidth availability
(feet) (kbps)
18,000 1,544
16,000 2,048
12,000 6,312
9,000 8,448

43. xDSL Family

44. xDSL family tree
• The xDSL "family tree" includes two main
branches
– Symmetric DSL  services provide identical
data rates upstream and downstream.
– Asymmetric DSL provides relatively lower
rates upstream but higher rates downstream.

45. xDSL Family Tree
• ADSL, G.Lite and RADSL
• HDSL, SDSL, and SHDSL
• VDSL (VADSL, BDSL)
• IDSL

46. ADSL
• Asymmetric Digital Subscriber Line was
designed to provide higher downstream data
rates at the expense of upstream rates.
• ADSL is technically capable of up to 6 Mbps
(roughly 6000 Kbps), but the service customers
actually receive generally performs at 2 Mbps or
lower for downloads and 512 Kbps for uploads.

47. ADSL
• Example:
– Many typical uses of the Web -- such as file
downloads and general web browsing --
benefit from greater downstream bandwidth
but require relatively little in the opposite
direction.

48. G.Lite
• Universal ADSL (also known as G.Lite) is
a form of ADSL that improves on one of
the weaknesses of regular ADSL --
installation.

49. ADSL & G.Lite
• Regular ADSL generally requires a
technician visit to the client site to install
the splitter device that divides the
frequency spectrum for voice and data.
• G.Lite does not require that this splitter be
installed, but it does so at the expense of
lower data rates.

50. ADSL & G.Lite
• G.Lite supports a maximum of 1,544 kbps
(384 kbps upstream)
• Whereas regular ("full-rate") ADSL can
support more than 8,000 kbps.

51. RADSL
• Rate-Adaptive DSL (RADSL), is an
implementation of ADSL that automatically
configures the modem at startup to adjust
its rate according to the quality of the
phone line.
• Like G.Lite, RADSL supports a much lower
maximum date rate (1,088 kbps) than
regular ADSL.

52. HDSL
• High Bit / Data-Rate DSL (HDSL) offers
the same bandwidth both upstream and
downstream.
• HDSL requires two phone lines to deliver
the basic data rate (1,544 kbps),
• It can deliver a maximum rate of 2,048
kbps using three lines.

53. SDSL
• Symmetric DSL(SDSL) improves on the
older HDSL technology by implementing
the same basic data rate (1,544 kbps)
while requiring only a single phone line.
• SDSL supports data rates up to 3,088
Kbps.

54. SHDSL
• Symmetric High-Bit-Rate DSL (SHDSL)
attempts to improve on both HDSL and
SDSL by only requiring a single line and by
integrating low-level services of interest to
small businesses.
• SHDSL technology can transport data
symmetrically at data rates from 192 Kbps
to 2,320 Kbps.

55. VDSL (BDSL)
• Very High Data-Rate DSL (VDSL)
originally named VADSL ('A' for
asymmetric) but later was extended to
support both symmetric and asymmetric
varieties of DSL.
• VDSL relies on fiber optic cabling.

56. VDSL
• VDSL needs shorter cable lengths than
most other forms of DSL (maximum 4,500
feet as compared to 18,000 feet for regular
ADSL), but it also achieves the highest
data rate (roughly 51,840 kbps).

57. VDSL
• The bandwidth levels supported by VDSL
are needed to support certain high-end
applications such as High-Definition
Television (HDTV) that requires, for
example, up to 20,000 kbps.

58. VDSL
• The performance of VDSL depends
significantly on the physical distance
traversed by wiring: Shorter distances
mean faster networking.

59. IDSL
• ISDN DSL (IDSL) implements a hybrid
DSL/ISDN solution.
• IDSL offers only limited data rates (128
kbps, although multiple circuits may be
bonded).

60. DSL & Cable Modem
• Speed
– Cable modem generally wins the speed battle
over DSL.
– Cable technology can, in theory, achieve
networking speeds of approximately 30 Mbps
(using a 100 Mbps NIC)
– Most forms of DSL cannot reach 10 Mbps.

61. DSL & Cable Modem
• Speed (cont.)
– cable modem technology delivers shared
bandwidth within the local neighborhood
– DSL delivers dedicated local bandwidth.

62. DSL & Cable Modem
• Security
– At Northwestern University, Kellogg
Information Systems
– “If ease of installation is important to you, KIS
suggests a cable modem over DSL. The
slightly more secure environment offered by
DSL is not enough to justify the added cost
and installation hassle."

63. DSL & Cable Modem
• Security (cont.)
– Many DSL and cable modem customers
choose to purchase routers to protect their
internal systems.

64. THANKS…..