rfc-4123 sip-h.323 interworking requirements speaker: yan-shiang wang adviser: quincy wu date:...
TRANSCRIPT
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)
SetupCall Proceeding
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)
SetupCall Proceeding
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}
H.323 Terminal IWF/GW SIP UA
INVITETo:[email protected]=IN IP4 5.6.7.8m=audio 9000 RTP/AVP 0
Connectfaststart={g711Ulaw,Tx,1.2.3.4:5000}{g711Ulaw,Rx}
200 OKc=IN IP4 1.2.3.4m=audio 5000 RTP/AVP 0
ACK
RTP RTCP
32
Call from H.323 to SIP
Setup (no faststart)
H.323 Terminal IWF/GW SIP UA
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}
H.323 Terminal IWF/GW SIP UA
INVITETo:[email protected]=IN IP4 1.2.3.4m=audio 5000 RTP/AVP 0
Connectfaststart={g711Ulaw,Tx,5.6.7.8:9000}{g711Ulaw,Rx}
200 OKc=IN IP4 5.6.7.8m=audio 9000 RTP/AVP 0
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