MEGACO/H.248 H323, SIP & MGCP, MEGACO SS7 PSTN CA SG MGCP - - PowerPoint PPT Presentation

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MEGACO/H.248 H323, SIP & MGCP, MEGACO SS7 PSTN CA SG MGCP - - PowerPoint PPT Presentation

Aug 26, 2023 381 likes •661 views

MEGACO/H.248 H323, SIP & MGCP, MEGACO SS7 PSTN CA SG MGCP GW TN GK GK GW TN PSTN CO TGW RGW H.323 RTP MCU TN TN MCU TN TN CA : Call Agent GW : Gateway TGW : Trunking Gateway GK : Gatekeeper RGW : Residential

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SLIDE 1

MEGACO/H.248

slide-2
SLIDE 2

2003/4/16 2 MEGACO

H323, SIP & MGCP, MEGACO

GW GK MCU GW : Gateway GK : Gatekeeper TN : Terminal MCU : Multipoint Control Unit TN

PSTN

CA TGW

RGW

CA : Call Agent TGW : Trunking Gateway RGW : Residential Gateway SG : Singling Gateway SS7 PSTN

CO SG

RTP MGCP H.323 TN TN GW GK MCU TN TN TN

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SLIDE 3

2003/4/16 3 MEGACO

H323, SIP & MGCP, MEGACO

H.323, SIP

peer-to-peer internet oriented intelligent endpoint

  • ptional GK

decentralized

Problems

maintenance

cost & scalability of large systems

signaling & media

control are coupled

interoperability with SS7

MGCP, MEGACO

client-server traditional telephony intelligent server

“dumb” terminal “stateless” terminal

centralized

Concept

gateway decomposed

separate call control from media ports CA, MG, SG

interoperability with PSTN

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SLIDE 4

2003/4/16 4 MEGACO

MEGACO Connection Model

Media Gateway Controller (MGC) Call Agent (CA)

3

Context Connection

2

Termination Endpoint

1 MEGACO MGCP

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SLIDE 5

2003/4/16 5 MEGACO

MEGACO Termination

A logical entity on a MG

  • that sources/sinks media/control streams

Termination ID

  • an arbitrary string assigned by the MG
  • at the time of their creation

Two kinds of Termination

  • Physical Interface
  • RTP stream

Root Termination

  • The entire MG itself
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SLIDE 6

2003/4/16 6 MEGACO

MEGACO Context

An association between a

collection of Terminations (within an media gateway)

Context ID

A 32 bit integer chosen by

the MG

∗ : ALL ; - : NULL; $ :

Choosing one

Null Context

Containing all Terminations

that are not associated to any other Termination

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SLIDE 7

2003/4/16 7 MEGACO

MEGACO Connection Model

Media Flow

Topology of a Context

describe the media flow between Terminations within a Context refer to Topology Descriptor

Mode of a Termination

describe the media flow at the ingress/egress of the media gateway refer to Media Descriptor Stream Descriptor Local Control Descriptor (receive-only, send/receive, …)

SCN 1 SCN 1 SCN 2 SCN 2 RTP RTP

Context

SCN 1 SCN 1 RTP RTP

Contexts in GW

SCN 1 SCN 1

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SLIDE 8

2003/4/16 8 MEGACO

Concept of Context

MGCP

CA RGW

RGW

MGCP

MEGACO

RTP IP

MGC MG

MG

MEGACO RTP IP

  • Context

Connection established after CRCX

Termination RTP Stream Termination SCN Channel

  • Add 2 Terminations into 1 context

Endpoint Endpoint

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SLIDE 9

2003/4/16 9 MEGACO

MEGACO Command Naming

(9) EndpointConfiguration (Endpoint-encode)

∋ Add, Modify, Move

(8) NotificationRequest (Endpoint)

∋ Add, Modify, Move

(7) AuditConnection (6) RestartInProgress (Endpoint) (8) ServiceChange (Termination) (5) Notify (Endpoint) (7) Notify (Termination) (NONE) (6) AuditCapability (Termination) (4) AuditEndpoint (5) AuditValue (Termination-cur) ≈ CreateConnection + DeleteConnection (4) Move (Termination) (3) DeleteConnection (Endpoint) (3) Subtract (Termination) (2) ModifyConnection (Endpoint) (2) Modify (Termination-descriptor) (1) CreateConnection (Endpoint) (1) Add (Termination to Context)

Similar Commands in MGCP MEGACO

(NONE)

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SLIDE 10

2003/4/16 10 MEGACO

Transaction & Message

Transaction

Multiple commands can be grouped. Commands are executed in sequence

If a command fails, the subsequent commands are not processed Not the case for optional commands O-”command-name” Messages

Concatenate multiple transactions The transactions are treated independently

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SLIDE 11

2003/4/16 11 MEGACO

MEGACO Transactions

Command 1 Command 2 Command 3 Action 1 for One Context Command 1 Action 2 for the Other Context Command 1 Command 2 Action 3 for Another Context Transaction

MGC to MG1: MEGACO/1 [123.123.123.41]:5555 Transaction = 10003 { Context = $ { Add = A4444, Add = $ { Media { Stream = 1 { LocalControl { …} Local { v=0 c=IN IP4 $ m= audio $ RTP/AVP 4 …} }}}}} MGC to MG1: MEGACO/1 [123.123.123.41]:5555 Transaction = 10003 { Context = $ { Add = A4444, Add = $ { Media { Stream = 1 { LocalControl { …} Local { v=0 c=IN IP4 $ m= audio $ RTP/AVP 4 …} }}}}}

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SLIDE 12

2003/4/16 12 MEGACO

Descriptors

To form the parameters of the commands/

responses

To provide additional information to qualify a

given command/response

Termination Descriptors Context Descriptors

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SLIDE 13

2003/4/16 13 MEGACO

Termination Descriptors

Command 1 Command 2 Command 3 Action 1 for One Context Command 1 Command 2 Action 2 for Another Context Transaction Topology Descriptor Media Descriptors Modem Descriptors MUX Descriptors Events Descriptors Signals Descriptors Digit Map Descriptors Audit Descriptors (no reply) Service Change Descriptors

  • Observed Events Descriptors

Event Buffer Descriptors Statistics Descriptors Error Descriptors Media Descriptors Modem Descriptors MUX Descriptors Events Descriptors Signals Descriptors Digit Map Descriptors Audit Descriptors (no reply) Service Change Descriptors

  • Observed Events Descriptors

Event Buffer Descriptors Statistics Descriptors Error Descriptors

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SLIDE 14

2003/4/16 14 MEGACO

Media Descriptor

Describe the various media streams A hierarchical descriptor Media descriptor Termination state descriptor Stream descriptor Local control descriptor Local descriptor Remote descriptor

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SLIDE 15

2003/4/16 15 MEGACO

Termination State Descriptor

ServiceStates

To indicate whether the termination is

available for use

“test”, “out of service”, “in service” EventBufferControl

To specify whether events detected by the

termination are to be buffered following detection or processed immediately

Other properties of a termination that are

not specific to any media stream

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SLIDE 16

2003/4/16 16 MEGACO

Stream Descriptor

Stream ID LocalControlDescriptor

Mode: sendonly, receiveonly, sendreceive, inactive,

and loopback

With respect to the exterior of the context

MGC specifies a set of choices for the session ReserveGroup and ReserveValue indicate the

resources should be reserved

LocalDescriptor and Remote Descriptor

Usage of SDP

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SLIDE 17

2003/4/16 17 MEGACO

Event & Signal Descriptors

Event Descriptor

RequestIdentifier A list of events that the MG should

detect and report

Signal Descriptor

On/off Timeout Brief

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SLIDE 18

2003/4/16 18 MEGACO

ServiceChange Descriptor

Used only in association with the ServiceChange

command

ServiceChangeMethod (The type of service change)

Graceful, the removal of existing terminations w/o interrupting existing

connections

Forced, an abrupt removal Restart, after a specified delay Disconnected, applied to the entire MG Handoff, from the old MGC; a new MGC is taking over Failover, from MG to MGC

ServiceChangeDelay, a number of seconds ServiceChangeReason

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SLIDE 19

2003/4/16 19 MEGACO

DigitMap Descriptor

A dialing plan A start timer, to start A short timer, when more digits are

needed

A long timer, to differentiate

different routing

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SLIDE 20

2003/4/16 20 MEGACO

ObservedEvents Descriptor

Mandatory in the Notify command

RequestIdentifier Optional time-stamp for each observed event

Except for the response of a ServiceChange

command

In a response to the AuditValue command

Events stored in the event buffer

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SLIDE 21

2003/4/16 21 MEGACO

Context Descriptors

Command 1 Command 2 Action 1 for One Context Command 1 Action 3 for Another Context Transaction Topology Descriptor

T2 T2 T1 T1 T3 T3 T2 T2 T1 T1 T3 T3 T2 T2 T1 T1 T3 T3 T2 T2 T1 T1 T3 T3 T2 T2 T1 T1 T3 T3 T2 T2 T1 T1 T3 T3

  • 1. No topology

descriptor

  • 2. T1, T2

isolate

  • 3. T3, T2
  • ne way
  • 4. T2, T3
  • neway
  • 5. T2, T3

bothway

  • 6. T1, T2

bothway Context 1 Context 2 Context 3 Context 4 Context 5 Context 6

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SLIDE 22
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SLIDE 23

2003/4/16 23 MEGACO

Call Flow: RGW to RGW

Internet

MGC RGW

RGW 123.123.123.4 124.124.124.222 125.125.125.5

1.(3) ServiceChange(ROOT): MG register with MGC 1 2 2.(4) Modify(A4444): MGC set Mode(SendReceive) & Events(al/of) A4444

  • A5555

3 4

NULL Context NULL Context

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SLIDE 24

2003/4/16 24 MEGACO

Call Flow: RGW to RGW

Internet

MGC RGW

RGW 123.123.123.4 124.124.124.222 125.125.125.5

  • 5. Notify(A4444): MG report an off hook event (time)

5 6

  • 6. Modify(A4444): MGC set Events (al/on, dd/ce, {DigitMap = Dialplan0})

Signals(cg/dt) A4444

  • A5555

DTMF detection/ Digit Map Complete Event

Call Progress Tone Generator/Dial Tone

NULL Context NULL Context

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SLIDE 25

2003/4/16 25 MEGACO

Call Flow: RGW to RGW

Internet

MGC RGW

RGW 123.123.123.4 124.124.124.222 125.125.125.5

  • 7. Notify(A4444): MG report a Digit Map Complete event(ds=916135551212,Meth=FM)

7 8

  • 8. Add(A4444,$:Mode(ReceiveOnly), Local(RTP))

A4444

  • A5555

Full Match Digit String A4445

Context ID = 2000

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SLIDE 26

2003/4/16 26 MEGACO

Call Flow: RGW to RGW

Internet

MGC RGW

RGW 123.123.123.4 124.124.124.222 125.125.125.5

  • 9. Add(A5555: Mode(SendReceive), Events(al/of), Signals(al/ri),

$: Mode(SendReceive), Local(RTP), Remote(...))

  • 10. Modify(A4444: Signals(cg/rt), A4445: Remote(…)))

A4444

  • A5555

A4445

Context ID = 2000

9 10

Context ID = 5003

A5556

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SLIDE 27

2003/4/16 27 MEGACO

Call Flow: RGW to RGW

Internet

MGC RGW

RGW 123.123.123.4 124.124.124.222 125.125.125.5

  • 11. Notify(A5555: Observed(al/of))
  • 12. Modify(A5555: Events(al/on), Signals()); to turn off ringing

A4444

  • A5555

A4445

Context ID = 2000

11 13

Context ID = 5003

A5556 12

  • 13. Modify(A4445: Mode(SendReceive), A4444: Signals())