Introduction to Telecommunications Technology Circuit Switching

1
Introduction to Telecommunications Technology--
Circuit Switching --

• Class Notes 7

ICS 620
2
Overview

• Circuit Switching
• SS7
• WAN
• ISDN
• ATM
• FDDI

3
Circuit Vs Packet Switching

• Dedicated circuits -- up 100 using public
  vendor circuits - usually point to point.
• Circuit switched -- uses PSTN, POTS or ISDN, up
  for period of call
• Packet switched -- connection is always up, usage
  is shared.

4
Types of Networks

• Public Switched Networks
• Both circuit and packet
• Private Networks
• Both circuit and packet
• Virtual Private Networks

5
Public Network
Public Network
SS7
Circuit Switched
L E C
L E C
Packet Switched
6
Dedicated Circuit System
L E C
L E C
Public Network
7
Switched Circuit System
Public Network
L E C
L E C
SS7
8
Setup Circuit System
Request Circuit
L E C
L E C
9
Setup Circuit System
Request Circuit
L E C
L E C
Circuit Establishment Confirmation
10
Setup Circuit System
Request Circuit
L E C
L E C
Circuit Establishment Confirmation
Transfer information
11
Setup Circuit System
Request Circuit
L E C
L E C
Circuit Establishment Confirmation
Transfer information
Disconnect
12
SS7

• Common Channel Signaling
• Uses a dedicated network for
• Call setup and teardown
• Network management maint.
• Provides the basis for global transparency of
  service
• Required for ISDN

13
Architecture of SS7
SSP
Subscriber
STP
STP
Subscriber
SSP
14
Architecture of SS7

• Service Switching Point
• Telco switches connected by SS7 links
• Service Transfer Point
• Switches that route SS7 messages to correct link
• Service Control Point
• Centralized network database for enhanced services

15
SS7
STP
STP
SSP
SSP
SSP
SSP
SSP
Tan- dem
LEC
LEC
Toll
Toll
16
SS7
STP
STP
SSP
SSP
SSP
SSP
SSP
Tan- dem
LEC
LEC
Toll
Toll
17
SS7
STP
STP
SSP
SSP
SSP
SSP
SSP
Tan- dem
LEC
LEC
Toll
Toll
18
ISDN

• Principles of ISDN
• The User Interface
• Objectives
• Benefits
• Services
• Architecture

19
Wide Area Network

• A communications network (voice or data) that
  serves users across a broad geographic area and
  uses transmission devices provided by common
  carriers.

20
Principles of ISDN

• Support of voice and non-voice applications using
  a limited set of standardized facilities
• Support of switched and non-switched applications
• Reliance on 64-kbps connections
• Intelligence in the network
• Layered protocol architecture
• Variety of configurations

21
The User Interface
Packet- switched network
Telephone
Data terminal
Circuit- switched network
ISDN central office
Customer ISDN interface
"Digital pipe"
Other networks
PBX
Data bases
Subscriber loop and ISDN channel structures
Alarm
Other services
LAN
22
Services

• Telephony
• Data transmission
• Facsimile
• Videoconferencing

23
ISDN Architecture
Network
Subscriber premises
gt64kbps non-switched capabilities
gt64kbps switched capabilities
Digital subscriber loop to C. O.
Subscriber interface to ISDN
64kbps ckt non-switched capabilities
Network Termination (NT)
Subscriber site or service provider
Terminal equipment (TE)
gt64kbps ckt switched capabilities
ISDN switch
ISDN switch
Packet switched capabilities
User-network signaling
Frame mode capabilities
Common- channel signaling capabilities
User-network signaling
24
Transmission Structure

• B Channel 64 kbps
• D Channel 16 or 64 kbps
• H Channel 384 (H0), 1536 (H1), or 1920 (H12)
  kbps
• Basic Rate Interface
• Primary Rate Interface

25
ISDN Channel Structures
B
Information Voice, Data
B
Basic
Signaling Overhead or telemetry, etc.
Basic Service Management rate 192 kbps Standard
throughput 144 kbps Composition B B D
channels, Synch framing
D
B
B
PCM voice channels
Primary
Primary Service Rate 1.544/2.048
Mbps Composition 2.048 Mbps 30 B at 64 kbps
each
2 D at 64 kbps 1.544
Mbps 23 B at 64 kbps each
1 D at 64 kbps
B
D
Signaling
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User-Network Interface Configuration
TE1
NT2
NT1
T
S
U
R, S, T, U Reference
interface points NT1 Network termination 1 NT2
Network termination 2
TA
TE2
S
R
TA Terminal adapter TE1 Terminal equipment
type 1 TE2 Terminal equipment type 2
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WHAT IS ATM?
1. REGISTRATION 2. CELL CREATION 3. PATH
CREATION - CALL SETUP - PC TO SWITCH PATH
SETUP - EDGE SWITCH TO OTHER SWITCHES OF PATH
- INTER-SWITCH COMMUNICATION 4. CELL
TRANSFER 5. CELL SWITCHING / INTRA-SWITCH
ROUTING 6. CELL DELIVERY 7. INTERCONNECTION TO
OTHER NETWORKS
Groom, F. (1999)
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SUPPLYING BANDWIDTH TO WHOM TO USERS
AT THEIR PC TO LAN USERS AT A HUB
AT A SWITCH ATTACHED TO A HUB AT
AN EDGE ROUTER AT AN EDGE ATM SWITCH
AT A C.O. WITH AN RBOC ATM SWITCH
AT A CARRIER POP WITH CARRIER SWITCH
Groom, F. (1999)
29
WHEN TO USE ATM WORKSTATION- CAD/CAM/CAE BACKBONE
- Multimedia, Desktop Video Conf. Heavy
Client Server Traffic Server
Connections METROPOLITAN- High Bandwidth
Connection High Quality Connection
Voice/Video
Data/Multimedia WAN- High Bandwidth Connection
High Quality Connection
Voice/Video Data/Multimedia
Groom, F. (1999)
30
SPEED OF ATM TRANSPORT
ATM SPEED 25 Mbps IBM 4B/5B 51 Mbps SONET 100
Mbps TAXI 4B/5B 155 MbpsSONET 622 Mbps SONET 2.4
Gbps SONET
Net Interface Speeds Circuit Emulation
1. 5 Mbps 45 Mbps
LANE INTERFACE 10 /100 Mbps Ethernet 16
Mbps TR
Groom, F. (1999)
31
Groom, F. (1999)
WHERE CONVERT PACKETS TO CELLS?
IBM Compatible
PC NIC
HUB Module
Switch Module
Enterprise Edge Router
RBOC or Carrier Edge Switch
ATM Proxy Client Egress Module
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NATIVE MODE ATM LAN
ATM WORKSTATION
ATM SERVER
ATM Server Application
ATM Workstation
Application
ATM API
ATM API
ATM UNI Signaling
ATM UNI Signaling
ATM SWITCH
AAL 1 2 3/4 5
AAL 1 2 3/4 5
ATM
ATM
ATM
ATM
Physical- ATM NIC
Physical-ATM NIC
Phys
Phys
51 OR 155 MBPS
155 MBPS
Groom, F. (1999)
33
ATM Cell Structure
IEC,1999
34
ATM Cell Header with VPI and VCI
35
ATM Service Classes Service Class Quality of
Service Parameter constant bit rate (CBR)
This class is used for emulating circuit
switching. The cell rate is constant with time.
CBR applications are quite sensitive to
cell-delay variation. Examples of applications
that can use CBR are telephone traffic (i.e.,
nx64 kbps), videoconferencing, and television.
variable bit ratenon-real time (VBRNRT) This
class allows users to send traffic at a rate that
varies with time depending on the availability of
user information. Statistical multiplexing is
provided to make optimum use of network
resources. Multimedia e-mail is an example of
VBRNRT.
IEC, 1999
36
ATM Service Classes-contd variable bit ratereal
time (VBRRT) This class is similar to VBRNRT
but is designed for applications that are
sensitive to cell-delay variation. Examples for
real-time VBR are voice with speech activity
detection (SAD) and interactive compressed video.
available bit rate (ABR) This class of ATM
services provides rate-based flow control and is
aimed at data traffic such as file transfer and
e-mail. Although the standard does not require
the cell transfer delay and cell-loss ratio to be
guaranteed or minimized it is desirable for
switches to minimize delay and loss as much as
possible. Depending upon the state of congestion
in the network, the source is required to control
its rate. The users are allowed to declare a
minimum cell rate, which is guaranteed to the
connection by the network.
37
ATM Service Classes-contd unspecified bit
rate (UBR) This class is the catch-all, other
class and is widely used today for TCP/IP.
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Virtual Circuits
39
ATM Cell Based Transmissions

25 Mb/s, 155 Mb/s, or
622 Mb/s
Switch-based

Cell-based transmissions
Dedicated capacity

53 byte cells
ATM Forum

Negotiated service
connection
Hub/
A
Router

End-to-end
A
A
connections
ATM
ATM
A
B
A
B
C
Hub/
B
B
B
Switch

Virtual circuits
Switch
Router
Building 1
Building 2
C
C
Hub/
C
Router
40
Overview

• What is FDDI?
• What makes it different?
• Where does it fit in the networking picture?
• Why would you use it?

41
Definition

• Fiber Distributed Data Interface (FDDI) is
• a LAN/MAN implementation
• token based
• dual, counter-rotating fiber rings
• transmission speed of 100 Mbps
• 4B/5B encoding of data
• ANSI X3T9.5

42
Layered Architecture
LLC
SMT
MAC
ISOCHRONOUS MACs (FDDI-II ONLY)
HYBRID RING CONTROL (FDDI-II ONLY)
PHY
PMD
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Frame Format
SFS
FCS Coverage
EFS
Preamble
SD
FC
DA
SA
INFO
FCS
ED
FS
SFS - Start of Frame Sequence INFO -
Information SD - Starting Delimiter FCS -
Frame Check Sequence FC - Frame Control EFS
- End of Frame Sequence DA - Destination
Address ED - Ending Delimiter SA - Source
Address FS - Frame Status
Token Format
Preamble
SD
FC
ED
44
Summary

• Circuit Switching
• WAN
• ISDN
• ATM
• FDDI