Download - U 4215 L Switching Signaling1 2
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This Lesson isThis Lesson is
UNCLASSIFIED//FOUOUNCLASSIFIED//FOUO
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U-4205L Telephony BasicsU-4205L Telephony BasicsPart 1Part 1
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DisclaimerDisclaimer• The images and media associated with this The images and media associated with this
presentation does not constitute endorsement presentation does not constitute endorsement by the United States Air Forceby the United States Air Force
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OverviewOverview
• Telecommunication SwitchingTelecommunication Switching
• Telecommunication SignalingTelecommunication Signaling
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Objectives and MSBsObjectives and MSBs
• Comprehend telephone switchingComprehend telephone switching– Describe the function of a central Describe the function of a central
officeoffice
– Describe the function of a end office Describe the function of a end office switchswitch
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Objectives and MSBsObjectives and MSBs
• Comprehend telephone switching Comprehend telephone switching (cont.)(cont.)– Describe the function of a tandem Describe the function of a tandem
switchswitch
– Describe hiearchary switchingDescribe hiearchary switching
– Describe dynamic non-hiearchary Describe dynamic non-hiearchary switchingswitching
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Objectives and MSBsObjectives and MSBs
• Comprehend telephone signalingComprehend telephone signaling– Define in band signalingDefine in band signaling
– Define out of band signalingDefine out of band signaling
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Public Switched Telephone NetworkPublic Switched Telephone Network(PSTN)(PSTN)
The worldwide collection of interconnected public The worldwide collection of interconnected public telephone networks that was designed primarily telephone networks that was designed primarily
for voice trafficfor voice traffic
www.linfo.org
PSTN
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Central OfficeCentral Office(CO)(CO)
• A building in which the phone lines in a home A building in which the phone lines in a home or office terminate and connect to a much or office terminate and connect to a much larger switching system larger switching system
• Connected to a much broader switching Connected to a much broader switching system in which switching offices are system in which switching offices are interconnected with trunk lines interconnected with trunk lines
• While the local loop is an analog circuit for While the local loop is an analog circuit for voice calls, once a call gets to the CO, it is voice calls, once a call gets to the CO, it is converted to a 64-Kbit/sec stream of digital converted to a 64-Kbit/sec stream of digital data for routing through the switching systemdata for routing through the switching system
Sheldon
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Telephone SwitchesTelephone Switches
Horack
• Private Branch Exchange– A private switching system normally used in the
commercial sector
• End Office Switch (Class 5)– A telephone central office switch that connects
directly to the customer. • Tandem Switch (Class 4)
– A network switch that serves in partnership with lesser switches (i.e. CO), and serves no end users directly
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Telephone SwitchesTelephone Switches
Freeman
• Primary Center Switch (Class 3)– Processes Calls being made beyond the limits of
a small geographical area
• Sectional Center (Class 2)– Typically connect to major toll centers within one
or two states or provinces• Regional Center (Class 1)
– Last resort" for final setup of calls when routes between centers lower in the hierarchy were not available, serves as an international gateway
Hierarchical SwitchingHierarchical Switching
• A group of interconnected sub-A group of interconnected sub-networks that control traffic through networks that control traffic through segmentationsegmentation
• Provided simplified switch designProvided simplified switch design
• Circuit security Circuit security
• OutagesOutages
X939 X243 X757 X912 X210 X312 X556 X404
4a 4b 4c 4d 4e
3a 3b 3c 3d 3e 3f 3g
2a 2b2d
1a
2c
1bClass 1Region
Class 2State
Class 3County
Class 4City
Class 5Local
850-939-1122 850-939-3344 850-243-5566 912-656-7788 210-756-1111
1c
PBX
50 Users
T1 24 Channels
Company BGI
HIEARCHARY SWITCHING
International Gateway
High Use
Route
High Use
Route
Dynamic Non-Hierarchical RoutingDynamic Non-Hierarchical Routing(DNHR)(DNHR)
• Implemented by AT&T after the Implemented by AT&T after the divestituredivestiture
• Intelligent control and reporting of traffic Intelligent control and reporting of traffic
• Integral for carriers to operate their Integral for carriers to operate their networks at peak efficiencynetworks at peak efficiency
• Introduced flexibility into network traffic Introduced flexibility into network traffic controlcontrol
939 243 656 712
T T
Class 4
Class 5
404
CLEC
Intelligent Network
Uses Switching Points To Access The Signaling Network
Dynamic Non-Hiearchical Routing
T
PBX
50 Users
T1 24 Channels
Company BGI850-939-1122 850-939-3344 850-243-5566 912-656-7788
SSP
SSP SSPSSP SSP
SSPSSP
T
SSP SSP
International Gateway
Telecommunication Signaling Telecommunication Signaling In Band SignalingIn Band Signaling
The exchange of signaling (call The exchange of signaling (call control) information between control) information between switches on the same circuit the switches on the same circuit the voice call rides onvoice call rides on
300 Hz 3400 Hz
Voice Band
2600 Hz
2000 Hz
Telecommunication Signaling Telecommunication Signaling Out of Band SignalingOut of Band Signaling
The exchange of information in order to The exchange of information in order to control a telephone call that is done on control a telephone call that is done on a channel that is dedicated for the a channel that is dedicated for the control purpose and separate from the control purpose and separate from the channels used for the telephone callchannels used for the telephone call
300 Hz 3400 Hz
Voice Band
3700 Hz USA3825 Hz (CCITT)
2000 Hz
Multi-Frequency SignalingMulti-Frequency Signaling
• A method utilizing five or six tone frequencies, two at a A method utilizing five or six tone frequencies, two at a time. time.
• Used for signaling between switchesUsed for signaling between switches
• Examples of multi-frequency signalingExamples of multi-frequency signaling– A A Local Loop to the End Office Switch– SOCOTEL France and Spain– Signaling System 5 (SS5) Country Specific– Inter-register Signaling 1 (R1) USA– Inter-register Signaling 2 (R2) Europe/Asia
Inter-register 1(R1) Inter-register 1(R1) SignalingSignaling USA USA
Frequency HZ
1 700 + 900
2 700 + 1100
3 900 + 1100
4 700 + 1300
5 900 + 1300
6 1100 + 1300
7 700 + 1500
8 900 + 1500
9 1100 + 1500
10 (0) 1300 + 1500
Control Signal 1700 + 700 -1300
System Check 1900
Idle Line 2600300 Hz 3400 Hz
Voice Band
2600 Hz
2000 Hz
In Band Signaling
Signaling System 5
300 Hz 3400 Hz
Voice Band
2000 Hz
3825 Hz (CCITT)
Frequency HZ
1 700 + 900
2 700 + 1100
3 900 + 1100
4 700 + 1300
5 900 + 1300
6 1100 + 1300
7 700 + 1500
8 900 + 1500
9 1100 + 1500
10 (0) 1300 + 1500
Control Signal 1700 + 700 -1300
System Check 1900
Idle Line 2600
Inter-register 2 (R2) Inter-register 2 (R2) SignalingSignaling Asia/Europe Asia/Europe
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Intelligent Network SignalingIntelligent Network SignalingSignaling System 7Signaling System 7
• Developed to meet the needs of an Developed to meet the needs of an all digital network all digital network
• Provides supervision of circuits, Provides supervision of circuits, address signaling, call progress address signaling, call progress signals and alerting notificationsignals and alerting notification
• Data network entirely dedicated to Data network entirely dedicated to inter-switch signalinginter-switch signaling
SS7 NetworkSS7 Network
939 939
Intelligent SignalingSignaling System 7
T
SSPSSP SSP
STP STP
850-939-1122 850-939-3344
Service Switching Point (SSP)Service Transfer Point (STP)Service Control Point (SCP)
Associated Signaling
SSPSSP
T1
Circuit
Signal
Non-associated Signaling
SSPSSP
T3
Circuit
Signal
T1
Non-associated Signaling
SSPSSP
T3
Circuit
Signal
STP STP
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• The North American Signaling ArchitectureThe North American Signaling Architecture• The North American signaling architecture defines a completely new and separate signaling network. The The North American signaling architecture defines a completely new and separate signaling network. The
network is built out of the following three essential components, interconnected by signaling links: network is built out of the following three essential components, interconnected by signaling links: • signal switching points (SSPs)signal switching points (SSPs)—SSPs are telephone switches (end offices or tandems) equipped with —SSPs are telephone switches (end offices or tandems) equipped with
SS7-capable software and terminating signaling links. They generally originate, terminate, or switch calls. SS7-capable software and terminating signaling links. They generally originate, terminate, or switch calls. • signal transfer points (STPs)signal transfer points (STPs)—STPs are the packet switches of the SS7 network. They receive and route —STPs are the packet switches of the SS7 network. They receive and route
incoming signaling messages towards the proper destination. They also perform specialized routing incoming signaling messages towards the proper destination. They also perform specialized routing functions. functions.
• signal control points (SCPs)signal control points (SCPs)—SCPs are databases that provide information necessary for advanced call-—SCPs are databases that provide information necessary for advanced call-processing capabilities.processing capabilities.
• Once deployed, the availability of SS7 network is critical to call processing. Unless SSPs can exchange Once deployed, the availability of SS7 network is critical to call processing. Unless SSPs can exchange signaling, they cannot complete any interswitch calls. For this reason, the SS7 network is built using a signaling, they cannot complete any interswitch calls. For this reason, the SS7 network is built using a highly redundant architecture. Each individual element also must meet exacting requirements for highly redundant architecture. Each individual element also must meet exacting requirements for availability. Finally, protocol has been defined between interconnected elements to facilitate the routing of availability. Finally, protocol has been defined between interconnected elements to facilitate the routing of signaling traffic around any difficulties that may arise in the signaling network. signaling traffic around any difficulties that may arise in the signaling network.
• To enable signaling network architectures to be easily communicated and understood, a standard set of To enable signaling network architectures to be easily communicated and understood, a standard set of symbols was adopted for depicting SS7 networks. Figure 2 shows the symbols that are used to depict symbols was adopted for depicting SS7 networks. Figure 2 shows the symbols that are used to depict these three key elements of any SS7 network. these three key elements of any SS7 network.
•Figure 2. Signaling Network ElementsFigure 2. Signaling Network Elements
• STPs and SCPs are customarily deployed in pairs. While elements of a pair are not generally co-located, STPs and SCPs are customarily deployed in pairs. While elements of a pair are not generally co-located, they work redundantly to perform the same logical function. When drawing complex network diagrams, they work redundantly to perform the same logical function. When drawing complex network diagrams, these pairs may be depicted as a single element for simplicity, as shown in Figure 3. these pairs may be depicted as a single element for simplicity, as shown in Figure 3.
http://www.iec.org/online/tutorials/ss7/
SSP SSPSSP
Central Office850-939-XXXX
LOCAL CALL
Within an Area Code and LATA
Central Office850-243-XXXX
TANDEM Non-Toll
LOCAL CALL
SSP SSPSSP
STP SCP
PSTN
IN/SS7
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Simplified SS7Simplified SS7
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