h.323 protocol

Adnan MehediAdnan Mehedi : 12-95467-1: 12-95467-1

Bidhan HalderBidhan Halder : 12-95846-2: 12-95846-2

Debabrata Bhowmik Debabrata Bhowmik : 11-95244-3: 11-95244-3

Khurshid AlamKhurshid Alam : 12-95403-1: 12-95403-1

Md. Habibur Rahman Md. Habibur Rahman : 11-94853-2: 11-94853-2

Tahmina AkterTahmina Akter : 12-95436-1: 12-95436-1

Islam AsifulIslam Asiful :: 11-95193-311-95193-3

PresentedPresented ByBy

OutlineOutline

• What is H.323What is H.323• Scope of H.323Scope of H.323• Why is H.323 ImportantWhy is H.323 Important• Historical Development StagesHistorical Development Stages• Elements of H.323 SystemElements of H.323 System• H.323 Network Architecture H.323 Network Architecture • H.323 Core ProtocolsH.323 Core Protocols• H.323: Call SignalingH.323: Call Signaling• Prospect/Future of H.323Prospect/Future of H.323

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What is H.323What is H.323

H.323* is a multimedia conferencing protocol, which includes voice, video and data conferencing for use over packet-switched networks

Real-time multimedia communications and conferencing for packet-based networks

* H.323 is “ITU-T Recommendation H.323: Packet-based multimedia communications systems”

3

Scope of H.323Scope of H.323

• Point-to-point and multipoint conferencing support

• Inter-network interoperability• Heterogeneous client capabilities• Audio and video codecs• Management and accounting support• Security• Supplementary services

4

Scope of H.323Scope of H.323

5

T1524040-96

Video I/O equipment

Audio I/O equipment

User Data ApplicationsT.120, etc.

System ControlUser Interface

Video CodecH.261, H.263

Audio CodecG.711, G.722,G.723, G.728,

G.729

System Control

H.245 Control

Call ControlH.225.0

RAS ControlH.225.0

ReceivePathDelay

H.225.0Layer

NetworkInterface

Scope of Rec. H.323

Why is H.323 ImportantWhy is H.323 Important

TrendTrendRapid growth of the InternetUniversal deployment of corporate LANs have

made packet-based networks ubiquitous

StandardizationStandardizationH.323 is a standard protocol has been widely

acceptedPromotes greater awareness, availability, and

acceptability of multimedia conferencing over packet-based networks

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Internet workingInternet workingBridges multimedia communications between

packet-based and switched-circuit networks (SCN)

SCN conferencing standards like H.320 (ISDN), H.321 (ATM), and H.324 (PSTN) can inter-operate with H.323 clients

Integrated servicesIntegrated servicesAdditional services such as e-mail, voice mail,

fax, call center functionality and video conferencing in an integrated environment

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InteroperabilityInteroperability

ConnectivityConnectivity

ETSI/ IMTC

ITU-T/ IETFRecommendations

ProductsProductsCustomers

VENDORS

StandardsStandards

8

Development Stages of H.323Development Stages of H.323

• H.323v1 published in 1996 & designed for LAN– Companies tried to do use H.323 in WAN,

large private VoIP networks, and the Internet• Guess what?• It worked very well

• H.323 was an early adopter of IETF protocols as RTP proved ability to carry real-time audio and video over IP networks– Indeed, H.323 was much more than a LAN

protocol name was changed in H.323 V2 (1998)

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Development Stages of H.323 (con)Development Stages of H.323 (con)Recognizing the fact that H.323 was much

more than a LAN protocol, the name was changed in H.323 Version 2 (1998)

Enhancements were made, including:SecurityPerformanceSupplementary ServicesScalability

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Development Stages of H.323 (con)Development Stages of H.323 (con)

H.323 v3 introduced a few modest improvements, mostly geared for better PSTN integration and scalability

New annexes were introduced:H.323 – UDP signalingH.323 – Simple endpoint typeH.225.0 – Communication between

administrative domains

11

Development Stages of H.323 (con)Development Stages of H.323 (con)

• H.323 v4 was approved Nov. 2000 and brings a number of enhancements to H.323. Areas of focus include:

– Scalability– Services – “Must Have” Features– Generic Extensibility Framework

• Current version of H.323 commonly referred to as "H.323v6” was published in 2006

12

ScalabilityScalability

Alternate GatekeepersBy using Alternate Gatekeepers,

endpoints are able to continue functioning in the face of one or more failures

Never Lose a Call!

T

GK GK GK GKXX

13

Scalability (con)Scalability (con)Endpoint Capacity Reporting

By utilize endpoint capacity reporting, Gatekeepers may select an endpoint that is best capable of handling the call

This is extremely useful for large scale deployments of Gateways and is also useful in call center applications

Never Lose a Call!GK GK GK GK GK

GW23%

GW77%

GW48%

GW64%

GW14%

GW36%

The GK selects the GW with the most capacity. H.323 endpoints report capacity in absolute terms, not in percentages.

14

ServicesServices

Annex K – Services via HTTPAnnex L – Stimulus ControlH.450.8 – Name identificationH.450.9 – Call Completion

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““Must Have” FeaturesMust Have” Features

Usage reportingCaller IdentificationAlias mappingBetter bandwidth management

(multicast)Fax enhancementsTunneling other protocols (Annex M.x)H.323-specific URLCall credit-related capabilitiesDTMF relay via RTP (RFC 2833)

16

Generic Extensibility FrameworkGeneric Extensibility Framework

The Generic Extensibility Framework (GEF) introduces a new means by which H.323 may be further enhanced or extended with optional features, which does not require changes to the current ASN.1 syntax

Work has already begunRobustness procedures (Annex R)Local number portability

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Components of H.323 SystemComponents of H.323 System

Terminalswhat people see/hear

Multipoint Control Units (MCUs)provides conference capabilities

Gatewayscontrol and ‘routing’

Gatekeeperaccess to other environments

Border Elements

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Components of H.323 SystemComponents of H.323 System

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TerminalsTerminals

An endpoint on the network which provides

for real-time, two-way communication with

other H.323 terminal, GW, or MCU

Terminal can be:TelephonesVideo phonesIVR devicesVoicemail Systems“Soft phones” (e.g., NetMeeting®)

20

T

Multipoint Control Units (MCUs)Multipoint Control Units (MCUs)Needed

only when multiparty conferences are desired

Functions:To manages call

signaling Provides capability of

videoconferencing with more than one party

Acts as a coordinator of multiparty conferences

2121

Gateways (GW)Gateways (GW)• Gateway (GW)

• used as interface H.323 between different networks e.g. LAN & PSTN

• Functions:• Data format translation• Audio/video codec

translation• Call setup, termination

from both sides of the network

22

Gatekeeper (GK)Gatekeeper (GK)

Gatekeeper is an optional component in H.323 system used for: Admission Control and Address Resolution

Endpoints do register themselves at a Gatekeeper All H.323 endpoints registered to a single GK

build an H.323 zoneH.323 zones are independent of physical network

topologyEach zone has only one GK (exception: Alternate

GKs)

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Gatekeeper FunctionalityGatekeeper FunctionalityMandatory Gatekeeper Functions

Address TranslationAdmission ControlBandwidth ControlZone Management

Optional Gatekeeper FunctionsCall-Control SignalingCall AuthorizationBandwidth ManagementCall Management

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Gatekeeper ZoneGatekeeper Zones

25

Gatekeeper

Gatekeeper

Gateway

Zone B

Zone A

The Internet

Border Elements (BE)Border Elements (BE)Co-located with Gatekeeper, Exchange

addressing information Participate in call authorization between

administrative domainsMay aggregate address information to

reduce the volume of routing information passed through the network

May assist in call authorization/authentication directly between two administrative domains or via a clearinghouse

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Using Elements (BE)Using Elements (BE)

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As with hierarchical Gatekeepers, Border Elements may send Access Request messages to other Border Elements and indicate where to send a reply

Border Elements may also reply directly to a request by utilizing address information cached from previous exchanges with other Border Elements

TGK

LRQ

GK/BE

ARQ

GK/BE

Access R

equest

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Router

H.323 terminal H.323 terminal ISDN videophone

Gateway

Gateway Phone

MCU

Gatekeeper

Protocols of H.323 Protocols of H.323 H.323 is an umbrella of four protocols:

• Registration Admission and Status (RAS)– define communications between endpoints and gatekeeper

– only needed when a gatekeeper exists

• H.245 - Connection Control for Capability Negotiations

• H.225/Q.931- Call Signaling (between endpoint and

gatekeeper, or between gatekeepers)

• Real-time Transport Protocol(RTP) - timely and orderly

delivery of audio and video streams

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H.323 Protocol stackH.323 Protocol stack

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Registration Admission and Status (RAS)Registration Admission and Status (RAS)• Defined in H.225.0• Allows an endpoint to request

authorization to place or accept a call• Allows a Gatekeeper to control access to

and from devices under its control• Allows a Gatekeeper to communicate the

address of other endpoints• Allows two Gatekeepers to easily

exchange addressing

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Registration Admission and Status (con)Registration Admission and Status (con)

32

T GKRRQ

RCF

ARQ

(endpoint is registered)

ACF(endpoint may place call)

DRQ

DCF(call has terminated)

H.225H.225H.225 Call Signaling

H.225 call signaling is used to establish a connection between two H.323 endpoints

Achieved by exchanging H.225 protocol messages on the call-signaling channel

call-signaling channel is opened between two H.323 endpoints or between an endpoint and gatekeeper

H.225 is the conference control protocol Master/slave determinationCapability exchangeManagement of media and data streams

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RTP/RTCPRTP/RTCPRTP/RTCP used for audio & video over IP

networksH.225 call signaling is used to establish a

connection between two H.323 endpoints Achieved by exchanging H.225 protocol messages

on the call-signaling channelcall-signaling channel is opened between two H.323

endpoints or between an endpoint and gatekeeper

Real Time Transport Protocol (RTP)end-to-end network transport functionpayload type, sequence number, timestamp

RTP Control Protocol (RTCP)quality feedback, RTP session control

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CODECsCODECsAudio

G.711 (popular codec for telephone n/ws)G.723.1 – more efficient

VideoH.261 codec (for channels with bandwidths

p*64 kb/s)H.263 codec (for low bit rate transmission

without loss of quality )

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Voice over IPVoice over IP

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Voice over IP (VoIP or Voice over Internet Protocol) commonly refers to the communication protocols, technologies, methodologies, and transmission techniques involved in the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet.

Other terms commonly associated with VoIP are:IP telephony, Internet telephony, voice over

broadband (VoBB), broadband telephony, IP communications, and broadband phone.

Voice over IP: ProtocolsVoice over IP: Protocols

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Voice over IP has been implemented in various ways using both proprietary and open protocols and standards. Examples of the network protocols used to implement VoIP include: H.323 Media Gateway Control Protocol (MGCP) Session Initiation Protocol (SIP) Real-time Transport Protocol (RTP) Session Description Protocol (SDP) Inter-Asterisk eXchange (IAX)

Voice over IP: Protocols (con)Voice over IP: Protocols (con)

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H.323 protocol was one of the first VoIP protocols found widespread implementation for long-distance traffic, as well as local area network services.

However, since the development of newer, less complex protocols such as MGCP and SIP, H.323 deployments are increasingly limited to carrying existing long-haul network traffic.

Session Initiation Protocol (SIP) has gained widespread VoIP market penetration.

A notable proprietary implementation is the Skype protocol, which is in part based on the principles of peer-to-peer (P2P) networking.

Voice over IP: Business useVoice over IP: Business use

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Session Initiation Protocol (SIP)Session Initiation Protocol (SIP)

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Session Initiation Protocol (SIP) is an Internet Engineering Task Force (IETF) standard protocol for initiating an interactive user session that involves multimedia elements such as video, voice, chat, gaming, and virtual reality.

The protocol can be used for creating, modifying and terminating two-party (unicast) or multiparty (multicast) sessions. Sessions may consist of one or several media streams.

Other SIP applications include video conferencing, streaming multimedia distribution, instant messaging, presence information, file transfer.

H.323 vs. SIPH.323 vs. SIP

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42


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44

H.323: Network Architecture H.323: Network Architecture

LAN1LAN1 WAN

Zone-1Zone-1 Zone-2Zone-2

Simple Network Architecture of H.323

45

MCUMCU MCUMCUGKGKGKGK

GWGW GWGW

LAN2LAN2TETE TETE

H.323 Protocol ArchitectureH.323 Protocol Architecture

Control Control Data Data Audio Video AV Control Audio Video AV Control GK ControlGK Control

signal + connection

46

Q.93Q.931/1/H.22H.2255

H.24H.2455

RTCPRTCPT.12T.1200

RASRAS

H.26H.26xx

G.7xG.7xxx

RTPRTP

UDPUDP

IPIP

TCPTCP

Protocol Relationships in H.323

H.323: Call signalingH.323: Call signaling

H.323 Call signal goes through 7 Phases:

Phase

Protocol

• Call admission RAS

• Call set-up Q.931

• Capability negotiation H.245

• Stable call RTP

• Channel closing H.245

• Call tear-down Q.931

• Call disengage RAS

““Fast Fast

connect”

connect”

““Fast Fast

connect”

connect”

47

H.323 Call Signaling ModelH.323 Call Signaling Model

• Direct Call Model

- Gatekeeper optional

• Gatekeeper Routed Call Model

48

Direct Call ModelDirect Call Model

49

optionalGatekeep

er Cloud

Terminal Endpoint 1

Q.931

H.245

RTP

RAS RAS

Terminal Endpoint 2

Gatekeeper Routed Call ModelGatekeeper Routed Call Model

50

GatekeeperCloud

Terminal Endpoint

1

Terminal Endpoint 2

Q.931

H.245

RTP

RAS Q.931

H.245RAS

Basic Call set-up with No GatekeeperBasic Call set-up with No Gatekeeper

51

t

Call set-up with Gatekeeper RoutingCall set-up with Gatekeeper Routing

t

52

Connect

ARQ

ACF

ACFAlerting

Alerting

Set-upSet-upCall Presiding

Connect

ARQ

GW GWGK

Call set-up with Gatekeeper RoutingCall set-up with Gatekeeper Routing

t

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Security Issue in H.323Security Issue in H.323

in H.323 v1

H.235 Security protocols ITU

authentication: end-point authentication

integrity: validation within a packet

privacy: encryption and decryption mechanism

non-repudiation: false denial of participation

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Call Enhancement in H.323Call Enhancement in H.323H.323 v2 & v3

H.450 on top of Q.931H.450.1 – Generic functional protocols and procedures [v1]H.450.2 – Call Transfer [v2]H.450.3 – Call DiversionH.450.4 – Call HoldH.450.5 – Call Park and Pick-up [v3]H.450.6 – Message Waiting indicationH.450.7 – Call WaitingH.450.8 – Name Identification[v4]H.450.9 – Call CompletionH.450.10 – Call OfferH.450.11 – Call Intrusion and so on…

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H.323: Market TodayH.323: Market Today

Today the biggest market for H.323 applications is Voice over IP. Why?Low bit-rate Internet connections make video

and data intensive applications less appealingIt’s a young industry– and with all such

industries, it takes time to mature good productsCompanies can provide VoIP services today at a

low cost and provide new competition to the incumbent carriers

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H.323: The Changing MarketH.323: The Changing Market

Tomorrow, expect to see video and data

conferencing to become more pervasive

Broadband connectivity is making it possible

Video and data are logically the next services

customers expect to find in conference rooms

and on their computer screens

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H.323: Beyond Voice over IPH.323: Beyond Voice over IP

Voice over IP opens the door to the next generation of communication products

It will take some time to migrate the world from PSTN to IP networksH.323 provides excellent interworking

between IP networks and the PSTNH.323 provides a strong foundation for new

multimedia products and services

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H.323: IP TelephonyH.323: IP Telephony

• IP Telephony with H.323 truly means Multimedia over IP

• IP Telephony is not Just Research Topic Anymore– is now real… there are many deployed products

and services that offer IP Telephony services– new kinds of services are now available to

customers using IP Telephony that were never possible before

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H.323: Makes All PossibleH.323: Makes All Possible

H.323 makes it possible to create and deploy new services quickly and to take advantage of multimedia capabilities

These services can embrace audio, video, and data conferencing

- Application Sharing - Electronic Whiteboard - File Transfer

- Instant Messaging - Click to Dial - Internet Call Waiting

- Web Call Parking - Call No-Waiting - Ad-Hoc Conferencing

- Voicemail Anywhere - Unified Messaging - Service Portability

- Services! - Services! - Services!

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H.323: for Service ProviderH.323: for Service Provider

H.323 is a proven technology that is

utilized in large networks, such as Genuity,

iBasis, ITXC, China Unicom, and others

Excellent integration with the PSTN

Gateways and residential devices are in

use today

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H.323: in the EnterpriseH.323: in the Enterprise

Multimedia conferencing devices show the

real potential of H.323 and multimedia

communication

With H.323 in the service provider network,

H.323 is a logical choice for the enterprise

The enterprise customer wants voice, video,

and data conferencing capabilities

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Importance of H.323Importance of H.323Interoperability - H.323 establishes methods for

receiving clients to communicate capabilities to the sender

Network independence - H.323 is not tied to any hardware or operating system

H.323 sets multimedia standards for the existing infrastructure (i.e. IP-based networks)

H.323 conference can include endpoints with different capabilities

H.323 provides multiple audio and video CODECs that format data according to the requirements of various networks, using different bit rates, delays, and quality options.

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Importance of H.323 (con)Importance of H.323 (con)Although H.323 can support conferences of three or

more endpoints without requiring a specialized multipoint control unit, MCU's provide a more powerful and flexible architecture for hosting multipoint conferences

Although H.323 can support conferences of three or more endpoints without requiring a specialized multipoint control unit, MCU's provide a more powerful and flexible architecture for hosting multipoint conferences

H.323 supports multicast transport in multipoint conferences

H.323 has the support of many computing and communications companies and organizations

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H.323: Pros and ConsH.323: Pros and Cons

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Recommendation AnnexesRecommendation Annexes

H.323Annex C – H.323 over ATMAnnex D – H.323 FAXAnnex E – UDP operationAnnex F – Simple EndpointsAnnex J – Security for Simple endpointsAnnex K – HTTP based call controlAnnex M – Tunneling of QSIG in H.323H.225.0Annex G – Inter-Domain CommunicationsAnnex H – ASN.1 Syntax

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ConclusionConclusionH.323 is a protocol that leverages the

strength of the packet-switched protocols from the IETF

Offers excellent integration with the PSTN

H.323 enables voice, video, and data

conferencingH.323 provides a solid foundation for new

services and the continued growth of Multimedia over IP

67

AcronymsAcronyms• ARQ –Admission Request message• BE – Border Element• GEF – Generic Extensibility Framework• GK – Gatekeeper• GW – Gateway• IETF – Internet Engineering Task Force• IMTC – International Multimedia Telecommunications

Consortium• IP – Internet Protocol• IVR – Interactive Voice Response• LAN – Local Area Network• LRQ – H.225.0 Location Request message• MCU – Multipoint Control UnitMC – Multipoint

Controller• MG – Media Gateway• MGC – Media Gateway Controller• MP – Multipoint Processor• PSTN – Public Switched Telephone Network

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AcronymsAcronyms• RFC – Request for Comments• RTP – Real-Time Transport Protocol• RTCP – Real-time Transport Control Protocol• TCS – H.245 Terminal Capability Set message• UDP – User Datagram Protocol• URL – Uniform Resource Locator• VoIP – Voice over IP• MC – Multipoint Controller• MG – Media Gateway• MGC – Media Gateway Controller• MP – Multipoint Processor• PSTN – Public Switched Telephone Network• RFC – Request for Comments• RTP – Real-Time Transport Protocol• RTCP – Real-time Transport Control Protocol• TCS – H.245 Terminal Capability Set message• UDP – User Datagram Protocol• URL – Uniform Resource Locator• VoIP – Voice over IP

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AcknowledgementAcknowledgement

• http://www.ip-voip.com/VOIP-protocols-h323-vs-SIP.htm

• http://en.wikipedia.org/wiki/Voice_over_IP• http://www.javvin.com/protocolH323.html• http://www.h323.org/• http://www.packetizer.com/ipmc/h323_vs_sip/• http://en.wikipedia.org/wiki/H.323• http://www.pulsewan.com/data101/

h323_basics.htm• http://www.cisco.com/en/US/tech/tk1077/

technologies_tech_note09186a00800c5e0d.shtml

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Questions ?Questions ?

Thank You

for

Kind Attention

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