rfc-4123 sip-h.323 interworking requirements

RFC-4123SIP-H.323 Interworking Requirements

Speaker: Yan-Shiang Wang

Adviser: Quincy Wu

Date: 2005/12/22

2

H.323 Introduction

Terminal Endpoint that offers real-time communications with

other h.323 endpoint Gateway

Translation services between the h.323 and others Gatekeeper

Controller MCU (Multipoint Control Unit)

Endpoint that manages multipoint conferences

3

H.323 ZoneTerminal Terminal Terminal Terminal

Gateway

Gatekeeper

GatewayMCU

SIPPSTN

Router

H.323

4

H.323 Protocol

H.225.0 RAS: Registration, Admission, Status

Between endpoints and gatekeepers Q.931: ISDN Layer 3 signaling protocol

Between endpoints

H.245 Establish and control media streams

Between two or more endpoints

5

H.323 Protocol Stack

Audio/VideoApplication

Terminal/Application Control

Audio/VideoCodecs RTCP

H.225.0RASSignaling

H.225.0Call (Q.931)Signaling

H.245ControlSignalingRTP

UDP TCP

Network Layer

Data Link Layer

Physical Layer

6

H.323 Protocol (cont.)

Gatekeeper Discovery: udp port 1718 RAS: udp port 1719

Q.931 udp or tcp port 1720

Audio codec G.711, G.722, G.723, G.728, G.729

Video codec H.261, H.263

7

RAS Signaling - Discovery

GatekeeperTerminal Gatekeeper

GRQ

GRJ

GCF

GRQ: Gatekeeper Request　 GRJ: Gatekeeper Reject　 GCF: Gatekeeper Confirm

GK discoverymulticast address

GRQ

GRQ

Terminal sends just one GRQ to the Gatekeeper discovery multicast address.Therefore, the Terminal will now proceed to register with which Gatekeeper.

8

RAS Signaling - Registration

GatekeeperTerminal

RRQ

RCF

URQ

UCF

RRQ: Registration Request　　 RCF: Registration ConfirmURQ: Unregistration Request　 UCF: Unregistration Confirm

／／／／

9

RAS Signaling - AdmissionGatekeeperTerminal

ARQ

ACF

Setup

ACF

ARQ: Admission Request　 ACF: Admission ConfirmDRQ: Disengage Request　 DCF: Disengage Confirm

／／／／

Terminal

／／

ARQ

DRQ

DCFDCF

DRQ

10

Q.931 SignalingTerminal

Setup

Call Proceeding

Connect

Release Complete

Terminal

Alerting

H.245 Session Establishment

H.245 Session Release

Media Exchange

11

Direct Endpoint CallTerminal

SetupCall Proceeding

Connect

Release Complete

Terminal

Alerting

H.245 Session Establishment

H.245 Session ReleaseMedia Exchange

GatekeeperGatekeeper

ACFARQ

DCFDRQ

ACFARQ

DCFDRQ

12

H.245 Signaling

TCS: Terminal Capability Set MSD: Master Salve Determination TCSA: TCS Ack MSDA: MSD Ack OLC: Open Logical Channel OLCA: OLC Ack OLCC: OLC Confirm ESC: End Session Command

13

H.245 ProcedureTerminal

TCS　MSDTCS　MSD

OLCA

Terminal

TCSA　MSDA

OLC

OLCAOLC

TCSA　MSDA

OLCC

ESCESC

RTP　 RTCP

Both Terminal sendinformation signallingat the same time, theydon’t need to waitAck signalling.

14

H.245 Procedure - Fast ConnectTerminal

Setup (faststart [logical channel info])

Call Proceeding

Connect (faststart [logical channel info])

Release Complete

Terminal

Alerting

Media Exchange

15

H.323 detailed header info

16

H.225 - Q.931 header

17

H.245 - Master Slave Determination

Terminal Type Value General terminal = 50 Gateway = 60 MCU = 190 MCU (currently managing a conference) = 240

Status Determination Number Random

Largest one is master

18

H.245 - MSD (cont.)

19

H.245 - OLC, OLCA, OLCR

20

SIP-H.323 Interworking

IWF (Interworking Function) interworking between H.323 and SIP

MSF (Media-Switching Fabric) optional entity within the IWF switches media such as voice, video, or f

ax from one network association to another

21

SIP-H.323 IWF

H.323Endpoint

H.323Gatekeeper

SIPUser Agent

SIPServer

H.323MCU

SIP-H.323 IWF

MCF

SIPUserAgent

H.323Terminal

22

SIP-H.323 IWF (cont.)

May be integrated into an H.323 GK or SIP server

Simply forwards media packets without modification Should not process media

MSF - Convert media from one encoding or format to another Out of scope for SIP-H.323 protocol translation

23

General Interworking Requirements

Opening of logical channels Should support the seamless exchange Should support open media channels

The channel can be opened at the MSF of the IWF When endpoints can’t open media channels themself

IWF H.323 features Should support fast connect Should support pre-granted ARQ (IWF in GK)

Overlapped sending Follow RFC3578 (from H.323) Q.931 (from SIP)

24

Overlap Signalling

Modern switches use en-bloc signalling Some parts of the PSTN still use overlap signalli

ng Sending only some digits of the callee's num

ber in the first signalling message Further digits are sent in subsequent signalli

ng messages

25

Interworking Analysis

simple call setup mapping addresses finding a subset of capabilities described by

H.245 and SDP conferencing and call services security and authentication

26

Register (IWF colocated with SIP server)

RRQ

RCF

H.323 Terminal Gatekeeper IWF/GW SIP UA

RRQ

RCF

RRQ

RCF

REGISTER

200 OK

27

RRQ (IWF colocated with H.323 GK)

RRQ

RCF

H.323 Terminal SIP ServerIWF/GW SIP UA

REGISTER

200 OK

REGISTER

200 OK

28

Invite (IWF colocated with SIP server)


H.323 Terminal Gatekeeper IWF/GW SIP UA

ARQACF

INVITE100 Trying

ARQACF

Alerting180 Ringing

Connect

200 OKACK

H.245　 Signaling

RTP　 RTCP

29

Setup (IWF colocated with H.323 GK)


H.323 Terminal SIP ServerIWF/GW SIP UA

ARQACF

Alerting180 Ringing

Connect

ACK

H.245　 Signaling

RTP　 RTCP

INVITEINVITE

180 Ringing200 OK

200 OK

ACK

100 Trying

negotiate between 200 OK and ACK

30

Call from SIP to H.323

Setup

H.323 Terminal IWF/GW SIP UA

INVITE

Connect (no faststart)

200 OKc=IN IP4 1.2.3.4m=audio 5000 RTP/AVP 0

ACK

RTP　 RTCP

TCS (g711Ulaw)

TCS (g711Alaw & g711Ulaw)TCSAck

TCSAckOLC (g711Ulaw)

OLCAck(1.2.3.4:5000)

OLC (g711Ulaw)OLCAck(5.6.7.8:9000)

31

Call from SIP to H.323 (with faststart)

Setupfaststart={g711Ulaw,Tx},{g711Ulaw,Rx,5.6.7.8:9000}


INVITETo:[email protected]=IN IP4 5.6.7.8m=audio 9000 RTP/AVP 0

Connectfaststart={g711Ulaw,Tx,1.2.3.4:5000}{g711Ulaw,Rx}


ACK

RTP　 RTCP

32

Call from H.323 to SIP

Setup (no faststart)


INVITE180 Ringing

Connect

ACK with updated SDPc=IN IP4 1.2.3.4m=audio 5000 RTP/AVP 8

RTP　 RTCP

TCS (g711Alaw)

TCS (g711Alaw & g711Ulaw)TCSAck

TCSAckOLC (g711Alaw)

OLCAck(1.2.3.4:5000)

OLC (g711Alaw)OLCAck(5.6.7.8:9000)

200 OK

33

Call from H.323 to SIP (with faststart)

Setupdestination:[email protected]={g711Ulaw,Tx},{g711Ulaw,Rx,1.2.3.4:5000}


INVITETo:[email protected]=IN IP4 1.2.3.4m=audio 5000 RTP/AVP 0

Connectfaststart={g711Ulaw,Tx,5.6.7.8:9000}{g711Ulaw,Rx}


ACK

RTP　 RTCP

34

Mapping Addresses

SIP address format

SIP-Address = (name-addr j addr-spec)name-addr = [display-name] ”<” addr-spec ”>”addr-spec = SIP-URLSIP-URL = ”sip:” [ userinfo ”@” ] hostport url-parameters

　 [headers]userinfo = user [ ”:” password ]hostport = host [ ”:” port ]host = hostname j IPv4addressurl-parameters = *(”;” url-parameter)url-parameter = user-param j . . .

35

Mapping Addresses (cont.)

H323 address format

{　 e164 IA5String (SIZE(1..128)) (FROM("0123456789\#*,")),　 h323-ID BMPString (SIZE (1..256)), ...,　 url-ID IA5String ( SIZE(1 .. 512)),-- URL Style address　 transport-ID TransportAddress, -- IPv4, IPv6, IPX etc.,...　 email-ID IA5String (SIZE(1..512)),　 partyNumber PartyNumber}

36

SIP to H323

h323-ID SIP-Address -> addr-spec exceeds 256 characters -> 414 (Address Too Long)

e164 “+”, “-” are removed “p” -> “,”

url-ID exceeds 512 characters -> 414 (Address Too Long)

email-ID exceeds 512 characters -> 414 (Address Too Long)

transport-ID If host is indicated as a dotted quad

37

SIP to H323 - examples

SIP - “sip:[email protected]” is converted to anH.323 - { h323-ID=”sip:[email protected]”, url-ID=”sip:[email protected]”, email-ID=“[email protected]” }

SIP - “sip:+1-212-555-1212:[email protected]; user=phone”H.323 – { e164=”12125551212”, h323-ID=”sip:+1-212-555-1212:[email protected]”, url-ID=”sip:+1-212-555-1212:[email protected]”, email-ID=“+1-212-555-1212:[email protected]” }

SIP - ”sip:[email protected]”H.323 - { h323-ID=”sip:[email protected]”, url-ID=”sip:[email protected]”, tranport-ID= IPAddress 10.1.2.3:1720, email-ID=“[email protected]” }

SIP - “A. Bell <sip:[email protected]>”H.323 - { h323-ID=”A.Bell <sip:[email protected]>”, url-ID=”sip:[email protected]”, email-ID=“A. Bell <[email protected]>” }

38

Mapping Addresses - H323 to SIP

If a url-ID is present and it is a SIP-URL If an h323-ID is present and it can be parsed as a v

alid SIP-Address, it is used If the transport-ID is present and it does not identify

the IWF, then it forms the hostport portion of the SIP URL and the user portion is constructed using h323-ID or e164

If the email-ID is present, then it is used in the SIP-URI

39

Security Considerations

Signaling security for H.323 is described in H.235

The IWF terminates not only the signaling protocols but also the security in each domain Users at endpoints have to trust the IWF

The IWF must not indicate the identity of a user on one side without first performing authentication

40

Reference

SIP-H.323 Signaling Gateway http://www1.cs.columbia.edu/~kns10/research/gw/

Interworking Between SIP/SDP and H.323 http://www.cs.columbia.edu/~kns10/publication/draft-singh

-sip-h323-01.pdf

Mapping of ISUP Overlap Signalling to SIP http://www.ietf.org/rfc/rfc3578.txt

Carrier Grade Voice Over IP Chapter 4, 5

rfc-4123 sip-h.323 interworking requirements

Documents

session establishmenth

udp port

gatekeeper rejectgcf

gatekeeper requestgrj

end session commandh

olc ackolcc

olc confirmesc

tcp port