ag_sp01_e1_p1 h.248 protocol v1.1 51p
DESCRIPTION
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A10&DSL D&T GroupA10&DSL D&T Group
AG_SP01_E1_P1AG_SP01_E1_P1
H.248 ProtocolH.248 ProtocolV1.1V1.1
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2ObjectivesObjectives
Upon the completion of this chapter, you will be able to:
Understand the concept of H.248 protocol
Understand the components of H.248 protocol
Describe the Call Flow Scenario (CFS)
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3Course OutlineCourse Outline
Concept of H.248 Protocol Components of H.248 Protocol
Call Flow Scenario
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4Background storyBackground story
First generation IP phone based on H.323 system
PSTN/ISDN
GW
GK
H323 TerminalMedia translation
Signaling switch
Call control
Limited Function extensibility
Limited system capacity extensibility
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5Evolution of H.248Evolution of H.248
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6Questions in mindQuestions in mind Who will use H.248 to communicate with each other?
What is the function of H.248
What is the characteristics of H.248
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7H.248 ProtocolH.248 Protocol
Softswitch
SG MG
BICC/SIP-T
H.248
RTP/RTCP
SIGTRAN
ISUP/MTP TDM Trunk
Control
Edge
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8H.248H.248MG
IAD
Answer of Q1.Answer of Q1.
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9Answer of Q2.Answer of Q2. What is the function of H.248?
It is primarily used to separate the call control logic from themedia processing logic in a gateway.
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Answer of Q3.Answer of Q3. Characteristics:
z ASN.1 and Text encode mode
z Open extensibility
z Better support on multi-media service and multi-meeting
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Course OutlineCourse Outline
Concept of H.248 Protocol
Components of H.248 Protocol Call Flow Scenario
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Context and TerminationContext and TerminationMedia GatewayMedia Gateway
ContextsContexts
TerminationTerminationTerminationTerminationTerminationTerminationTerminationTerminationTerminationTerminationTerminationTerminationTerminationTerminationTerminationTerminationTerm. XTerm. X
TerminationsTerminations
Context. XContext. X
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Terminology InterpretationTerminology Interpretation Termination
z DefinitionSource and Destination of a media stream. z Semi-permanent termination: physical termination. For example:
ports in a IAD
z Ephemeral termination: a information stream. For example: a RTP voice media.
z Root termination: Device itself.
Contextz Definition: represents the relationship between a group of
terminations. (who hears/sees whom)
z Null context: empty context. Represents terminations that havent establish relationship with others.
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Connect ModelConnect Model
CONTEXTCONTEXT
TerminationTermination
SCN Bearer SCN Bearer ChannelChannel
TerminationTermination
SCN Bearer SCN Bearer ChannelChannel
Media GatewayMedia Gateway
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Null ContextNull Context
Null CONTEXTNull CONTEXT
TerminationTermination
SCN Bearer SCN Bearer ChannelChannel
TerminationTermination
SCN Bearer SCN Bearer ChannelChannel
Media GatewayMedia Gateway
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Call waiting SampleCall waiting Sample
Media Gateway
CONTEXT C1
Term. T2
RTP Stream
Term. T1
SCN Bearer Channel
Term. T3SCN Bearer
Channel
CONTEXT C2
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Call waiting SampleCall waiting SampleMedia Gateway
CONTEXT C1
Term. T2
RTP Stream
Term. T3SCN Bearer
Channel
CONTEXT C2
Term. T1
SCN Bearer Channel
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ContextContext Context Characteristic
z ContextID: Identification of Context
z Topology: Direction of media stream flow
z Priority: Priority information related to context
z Emergency call id: identification of emergent call info. Call
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TerminationTermination Termination ID
z Identification of termination, assigned by MG
Termination descriptorz Property: service status, media passage property
z Event: on_hook, off_hook etc.
z Signal: dialing tone, DTMFsignaling etc.
z Statistics: accumulate statistical data and report to MGC
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DescriptorDescriptor Descriptor
z Definition: a syntax element (data structure), used
to describe the property of termination
H248 V1. defines 19 descriptors7 categoriesz Status: TerminationState, Modem;
z Media stream: Media_stream, local, remote, local control
multiplex;
z Event related: Event, digitmap, eventbuffer,
Observedevents; Signals;
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PackagePackage Package
z Definition: systematic extensibility of defining characteristics that havent been defined in termination
Common Packagesz al (analog line management package)
z cg (call procedure management package)
z dd (DTMF detection package)
z au (audio unit package)
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TransactionTransaction
Sender Receiver
TransactionRequest
TransactionReply/
TransactionPending
TransactionResponseAck
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TransactionTransactionTransactionRequest(TransactionId {
ContextID {Command _ Command}, . . .
ContextID {Command _ Command } })
TransactionReply(TransactionID { ContextID { Response _ Response },
. . . ContextID { Response _ Response } })
TransactionPending(TransactionID { } )
Transaction
API
Structure
TransactionResponseAck(TransactionID { } TransactionID{ })
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CommandsCommands
MGMGC
Add
MGCMGAdd a termination to a context, Create a context when contextID is not specified
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CommandsCommands
MGC
Add
Modify MGCMGModify the property,event or signal parameters of a terminal
MG
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CommandsCommands
MGC
Add
Modify
subtract
MGCMGDelete a terminal from a contextDelete the context if there is no more terminals in the context
MG
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CommandsCommands
MGC
Add
Modify
subtract
Move
MGCMGMove a terminal from one context to another
MG
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CommandsCommands
MGC
Add
Modify
subtract
Move
AuditValue
MGCMGObtain the current status, event, signal and statistics information of a terminal
MG
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CommandsCommands
MGC
Add
Modify
subtract
Move
AuditValue
AuditCapability
MGCMGObtain the possible capacity (characteristics, event, signal) of a MG
MG
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CommandsCommands
MGC
Add
Modify
subtract
Move
AuditValue
AuditCapability
Notify
MGMGCAllows the MG to notify the SS for any event change
MG
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CommandsCommands
MGC
Add
Modify
subtract
Move
AuditValue
AuditCapability
Notify
ServiceChange
MGCMGor MGMGCMGCMG
Start serviceQuit service
MGMGC Start serviceQuit serviceRegistration
MG
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TransportTransport
Softswitch
MG
H.248
TCP/UDP
IPH.248
Three-way Handshake
Port 2944: Text-encoded
Port 2945: Binary-encoded
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TransportTransport
Restart timer of every MG is needed to protected against restart avalanche
Timer should be initiate a random value between 0 and a Maximum waiting delay(MWD)
MGC
MG MG MG MG
ServiceChange
Restart Avalanche
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Course OutlineCourse Outline
Concept of H.248 Protocol
Components of H.248 Protocol
Call Flow Scenario
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ScenariosScenarios Gateway Log-in/out Call Setup Call Termination
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Gateway log in/outGateway log in/out
SSIAD
SVC_CHG_REQ
SVC_CHG_REPLY
MEGACO/1 [10.66.100.12]:2944 Transaction = 9998 {
Context = - {
ServiceChange = ROOT {Services {
Method=Restart,
ServiceChangeAddress=2944, Profile=ResGW/1}
}
}
}
MEGACO/1 [10.66.100.1]:2944
Reply = 9998 {Context = -
{ServiceChange = ROOT {Services
{ServiceChangeAddress=2944, Profile=ResGW/1} } }
}
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SSIAD
NTFY_REQ
MEGACO/1 [10.66.100.12]:2944
Transaction = 49414
{ Context = -
{
Notify = AG58900 {
ObservedEvents = 2000{
20020403T08131100 : al/of
}
}
}
MEGACO/1 [10.66.100.1]:2944
P=49414{C=-{N=AG58900}}
IAD
Off_hook
NTFY_REPLY
Call SetupCall Setup
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SSIADMEGACO/1 [10.66.100.12]:2944
Reply = 25218
{
Context = -
{
Modify = AG58900
}
}
IAD
MOD_REQ
MOD_REPLYDial-tone
MEGACO/1 [10.66.100.1]:2944 T=25218{ C=-{MF=AG58900{DM=DM999264604954 {(0x.|11x|[2-8]xxxxxxx)},E=2002{dd/ce{ DM=DM999264604954 },al/on,al/fl},SG{cg/dt}}}}
Call SetupCall Setup
Off_hook
NTFY_REQ
NTFY_REPLY
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SSIADMEGACO/1 [10.66.100.12]:2944
Transaction = 49415
{
Context = -
{ Notify = AG58900{
ObservedEvents = 2002 {
20020403T08131500 : dd/ce
{ ds = 26778086" , Meth = UM } } } } } MEGACO/1
[10.66.100.1]:2944 Reply=49415{Context=-{Notify= AG58900}}
IAD
NTFY_REPLY
NTFY_REQ
Call SetupCall Setup
Off_hook
NTFY_REQ
NTFY_REPLY
MOD_REQ
Dial-tone MOD_REPLY
Dialing
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SSIADMEGACO/1 [10.66.100.12]:2944
Reply = 10003 {
Context = 2000 {
Add = AG58900,
Add=RTP/00000{
Media {
Stream = 1 {
Local {
v=0
c=IN IP4 10.66.100.12m=audio 2222 RTP/AVP 0 4a=ptime:30a=recvonly}}}}}}
MEGACO/1 [10.66.100.1]:2944 Transaction = 10003 {Context = $ {Add = AG58900,Add = $ {Media {Stream = 1 {LocalControl {Mode = ReceiveOnly,nt/jit=40 ; in ms},Local {v=0 c=IN IP4 $ m=audio $ RTP/AVP 0 4a=ptime:30}}}}}}
IAD
ADD_REQ
ADD_REPLY
Call SetupCall Setup
Off_hook
NTFY_REQ
NTFY_REPLY
MOD_REQ
MOD_REPLY
NTFY_REQ
NTFY_REPLY
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SSIAD
MEGACO/1 [10.66.100.1]:2944
Transaction = 50003{Context = $ {Add = AG58901 { Media {Stream = 1 {LocalControl{Mode=SendReceive} }},Events=1234{al/of},Signals {al/ri}},Add = ${Media {Stream =1{LocalControl{Mode=SendReceive,nt/jit=40 ; in ms}, Local {v=0c=IN IP4 $m=audio $ RTP/AVP 0 4 8a=ptime:30},Remote {v=0c=IN IP4 10.66.100.12m=audio 2222 RTP/AVP 0 4a=ptime:30} ;}}}}}
MEGACO/1 [10.66.100.13]:2944 Reply = 50003 {Context = 5000 {Add = AG58901,Add = RTP/00002{Media {Stream = 1 {Local {v=0c=IN IP4 10.66.100.13m=audio 1111 RTP/AVP 0}} ; }}}}
IAD
ADD_REQ
ADD_REPLY
Call SetupCall Setup
Off_hook
NTFY_REQ
NTFY_REPLY
MOD_REQ
MOD_REPLY
NTFY_REQ
NTFY_REPLY
ADD_REQ
ADD_REPLY
ring
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SSIAD
MEGACO/1 [10.66.100.12]:2944
Reply = 10005
{ Context = 2000
Modify = AG58900
Modify = RTP/00000
}
}
MEGACO/1 [10.41.6.1]:2944 Transaction = 10005 {Context = 2000 {Modify = AG58900 {Signals {cg/rt}},Modify = RTP/00000 {Media {Stream =1 {Remote {v=0c=IN IP4 10.66.100.13m=audio 1111 RTP/AVP 0}} ;}}}}
IAD
MOD_REQ
MOD_REPLYRing_back
Call SetupCall Setup
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SSIAD
MEGACO/1 [10.66.100.1]:2944 Reply = 50005 {Context = 5000 {Notify = AG58901}}
MEGACO/1 [10.66.100.13]:2944 Transaction = 50005 {Context = 5000 {Notify = AG58901{ObservedEvents =1234 {19990729T22020002:al/of}}}}
IAD
MOD_REPLY
OffhookNTFY_REQ
NTFY_REPLY
Call SetupCall Setup
MOD_REQ
Ring_back
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SSIAD
MEGACO/1 [10.66.100.1]:2944 Transaction = 10006 {Context = 5000 {Modify = AG58901 {{E=2001{al/on,al/fl},Signals { }}}}
MEGACO/1 [10.66.100.13]:2944 Reply = 10006 {Context = 5000 {Modify = AG58901 }}
IAD
MOD_REPLY
Offhook
NTFY_REPLY
MOD_REQ
MOD_RERLY
Call SetupCall Setup
MOD_REQ
Ring_back
NTFY_REQ
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SSIAD
MEGACO/1 [10.66.100.12]:2944 Reply = 10006 {Context = 2000 {Modify = AG58900, Modify = RTP/00000}}
MEGACO/1 [10.66.100.1]:2944 Transaction = 10006 {Context = 2000 {Modify = AG58900{ Signals={ } },Modify = RTP/00000{Media {
Stream = 1 {LocalControl {
Mode=SendReceive}}}}}}
IAD
MOD_REPLY
Offhook
NTFY_REPLY
MOD_REQ
MOD_RERLY
MOD_REQ
MOD_REPLY
Conversation Established
Call SetupCall Setup
MOD_REQ
Ring_back
NTFY_REQ
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SSIAD
MEGACO/1 [10.66.100.1]:2944 Reply = 50008 {Context = 5000{Notify = AG58901}}
MEGACO/1 [10.66.100.13]:2944 Transaction = 50008 {Context = 5000 {Notify = AG58901{ObservedEvents =1235 {19990729T24020002:al/on} } } }
IAD
NTFY_REQ
NTFY_REPLY
Onhook
Call TerminationCall Termination
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SSIAD
MEGACO/1 [10.66.100.1]:2944 Transaction = 10007 {Context = 2000 {Modify= AG58900{signals { cg/bt }}}}
MEGACO/1 [10.66.100.12]:2944 Reply = 10007 {Context = 5000 {Modify = AG58900 }}
IAD
NTFY_REPLY
Onhook
MOD_REQ
MOD_REPLY
Call TerminationCall Termination
NTFY_REQ
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SSIAD
MEGACO/1 [10.66.100.1]:2944 Transaction = 50009 {Context = 5000 {Subtract = AG58901{Audit{Statistics}},Subtract = RTP/00002{Audit{Statistics}}}}
MEGACO/1 [10.66.100.13]:2944 Reply = 50009 {Context = 5000 {Subtract = AG58901 {Statistics {nt/os=45123, ; nt/dur=40 ; }},Subtract = RTP/00002{Statistics {rtp/ps=1245,nt/os=62345,rtp/pr=780, nt/or=45123, rtp/pl=0, rtp/jit=27,rtp/delay=48 }}}}
IAD
NTFY_REPLY
SUB_REQ
SUB_REPLY
Onhook
MOD_REQ
MOD_REPLY
Call TerminationCall Termination
NTFY_REQ
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SSIAD IAD
SUB_REQ
SUB_REPLY
Onhook
NTFY_REPLY
Conversation Terminated
SUB_REQ
SUB_RERLY
MEGACO/1 [10.66.100.1]:2944 Transaction = 50009 {Context = 2000 {Subtract = AG58900{Audit{Statistics}},Subtract = RTP/00000{Audit{Statistics}}}}
MEGACO/1 [10.66.100.12]:2944 Reply = 50009 {Context = 2000 {Subtract = AG58900 {Statistics {nt/os=45123, ; nt/dur=40 ; }},Subtract = RTP/00000 {Statistics {rtp/ps=1245,nt/os=62345,rtp/pr=780, nt/or=45123, rtp/pl=0, rtp/jit=27,rtp/delay=48 }}}}
MOD_REQ
MOD_REPLY
Call TerminationCall Termination
NTFY_REQ
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SS7 - H.248 SS7 signalingSS7 - H.248 SS7 signaling
Softswitch
TGTG
SG SG
Database ApplicationServer
ZTE
LS1 ZTELS2
3. Analysis & Routing
1. IAM
2. IAM
4. Add
5. Reply of Add
6. Add
7. Reply of Add
8. IAM11. ACM
9. IA
M10
. ACM
14. ACM
13. ACM
12. Modify(Notify)17. Modify
16. ANM
19. ANM
18. ANM
15. A
NM
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