Upload
cristhian-ona-p
View
156
Download
9
Embed Size (px)
Citation preview
ISSUEISSUE
Fixed Network Curriculum
Development Section
Fixed Network Curriculum
Development Section
OAA000005H.248/MeGaCo protocol
OAA000005H.248/MeGaCo protocol
2.02.0
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
2
Objective Objective
Functions of H.248/MeGaCo protocol
H.248/MeGaCo commands
Meanings and usage of parameters in
H.248/MeGaCo commands
Message interaction process of
H.248/MeGaCo protocol
After this session, you will learn:
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
3
References References
Product Manual -- Technical Manual – Signaling and
Protocols -- Chapter 4 H.248 Protocol
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
4
About this session About this session
Section 1 Overview
Section 2 Message Structure
Section 3 Call Flow
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
5
Bearer Control Protocols Bearer Control Protocols
Bearer control protocols are used for
the communication between Media
Gateway Controller (MGC) and Media
Gateway (MG).
As the control-layer equipment,
SoftX3000 supports two bearer
control protocols: MGCP and H.248.
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
6
Concept Concept
H.248 and MeGaCo refer to the same kind of protocol. It is an achieveme
nt from the efforts of both ITU and IETF. It is named H.248 by ITU-T and
MeGaCo by IETF.
H.248 comes into being on the basis of MGCP and is combined with feat
ures of other media gateway control associated protocols.
The function structure of H.248 is similar to that of MGCP. In NGN, both
H.248 and MGCP can be used between SoftX and most components.
MGCP is deficient in its descriptive capability, which restricts its applica
tions in large gateways. For those large-scaled gateways, H.248 is a muc
h better choice.
MGCP message transportation depends on UDP packets over IP network,
and H.248 signaling messages may be based on multiple bearers such a
s UDP/TCP/SCTP.
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
7
H.248 Implementation in SoftX3000 H.248 Implementation in SoftX3000
PSTN
SoftPhone
TMG8010
MRS
IAD
E-phone E-phone
IP CoreMGCP/SIP/H.323
SS7
E1
Sigtran
H.248
MGCP
MGCP/H.248
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
8
Terms Terms
Media Gateway (MG):
An MG converts media provided in one type of network to the
format required in another type of network.
Media Gateway Controller (MGC):
It controls the call state pertaining to connection control of media
channels of MG.
Termination:
A Termination is a logical entity on an MG, capable of sending
and/or receiving one or more streams. A Termination is described
by a number of characterizing properties, which are grouped in a
set of descriptors included in commands. One termination belongs
to one and only one context at any time.
Context: A context is the association among terminations. It
describes topology relationships among terminations and
media-mixed/switched parameters.
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
9
Terms Terms
Termination
SCN Bearer Channel
Termination
SCN Bearer Channel
Termination
RTP Stream
Context
Context
Context
Media Gateway
Null Context
*
Termination
SCN Bearer Channel
Termination
SCN Bearer Channel
Termination
RTP Stream *
Termination
RTP Stream *
Context
Context: A context is the association among terminations. It
describes topology relationships among terminations and
media-mixed/switched parameters.
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
10
Four Attributes of a Context Four Attributes of a Context
Context ID: The identifier of a context.
Topology structure: Who hears/sees whom, flow
direction of media.
Priority: Providing the prior handling information of a
context.
Emergency: Providing the emergent handling
information of a context.
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
11
Protocol Stack Protocol Stack
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
12
About this session About this session
Section 1 Overview
Section 2 Message Structure
Section 3 Call Flow
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
13
Message Mechanism of H.248 Message Mechanism of H.248
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
14
Protocol Message Protocol Message
The unit of information is message.
A message can contain multiple transactions.
A message has a header, which contains the ID of the
sender.
Each Message has a version number, indicating the
version followed by the protocol message.
There is no relationship among the transactions in a
message. They are treated independently.
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
15
Message StructureMessage Structure
Megaco/H.248 message
Trans Hdr
Req or Reply Req or Reply Req or Reply
Transaction Transaction Transaction....Header
CommandCtx PropertiesCtx Hdr Command....
Trans Hdr
Action Action....
....Descriptor Descriptor
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
16
Code of Protocol Message Code of Protocol Message
The code of a protocol message can be in the text format
or the binary format.
MGC must support both formats, while MG can support
either one.
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
17
Commands Commands
Commands Direction Description
Add MGC→MG used to add a Termination to a Context. If no ContextID is specified, a Context will be generated and then a Termination is added into it.
Modify MGC→MG used to modify the properties, events and signals of a Termination.
Subtract MGC→MG used to remove a Termination from a Context and return statistics on the Termination's participation in the Context. The Subtract command on the last Termination in a Context deletes the Context.
Move MGC→MG used to move a Termination from one Context to another.
H.248 protocol defines eight commands, all of which are sent to MG by MG
C except the command “Notify”, which is sent to MGC by MG. The comman
d “ServiceChange” can be sent by either the MG or the MGC. .
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
18
Commands (cont.)Commands (cont.)
Commands: Direction meanings
AuditValue MGC→MG used to return the current state of properties, events, signals and statistics of Terminations.
AuditCapabilities MGC→MG used to return a collection of termination capabilities.
Notify MG→MGC used to allow MG to notify MGC of the detected event.
ServiceChange MGC↔MG used to allow the MG to notify the MGC that a Termination or group of Terminations is about to be taken out of or into service. ServiceChange is also used by the MG to announce its availability to an MGC (registration), and used for notification of MGC suspension and active/standby switchover.
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
19
About this session About this session
Section 1 Overview
Section 2 Message Structure
Section 3 Call Flow
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
20
Scenario 1 – Registration Scenario 1 – Registration
SoftX3000MG
SVC_CHG_REQ
SVC_CHG_REPLY
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
21
Scenario 2 – Initiation of MGScenario 2 – Initiation of MG
SoftX3000MG
MOD_REPLY
MOD_REQ
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
22
SoftX3000Termination1UserA Termination2 UserB
Off-hook
1 NTFY_REQ
NTFY_REPLY
2 MOD_REQMOD_REPLYdial-tone
dialing
5 ADD_REQ
ADD_REPLY
RingingRingback tone
8 NTFY_REQ
NTFY_REPLY
Off-hook
3 NTFY_REQ
NTFY_REPLY
4 ADD_REQADD_REPLY
6 MOD_REQMOD_REPLY
7 MOD_REQ
MOD_REPLY
Scenario 3 – Successful call Scenario 3 – Successful call
9 MOD_REQ
MOD_REPLY
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
23
SoftX3000Termination1UserA Termination2 UserB
Conversation
On-hook
On-hook
10 MOD_REQ
MOD_REPLY
11 NTFY_REQNTFY_REPLY
12 MOD_REQMOD_REPLY
13 SUB_REQ
SUB_REPLY
15 MOD_REQMOD_REPLY
14 MOD_REQMOD_REPLY Busy-tone
16 NTFY_REQ
NTFY_REPLY
17 SUB_REQSUB_REPLY
18 MOD_REQ
MOD_REPLY
Scenario 3 – Successful call (cont.) Scenario 3 – Successful call (cont.)
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
24
SoftX3000SG AMG UserB
1 ADD_REQ
ADD_REPLY 2 ADD_REQ
ADD_REPLY
Ringing
5 NTFY_REQ
NTFY_REPLY
Off-hook
3 MOD_REQ
MOD_REPLY4 MOD_REQMOD_REPLY
6 MOD_REQ
MOD_REPLY7 MOD_REQ
MOD_REPLY
TGIAM
ACM
ANM
Conversation
Scenario 4 – Successful trunk call Scenario 4 – Successful trunk call
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
25
SoftX3000SG AMG UserBTG
8 NTFY_REQ
NTFY_REPLY
On-hook
9 MOD_REQ
MOD_REPLY
10 SUB_REQ
SUB_REPLY
11 SUB_REQ
SUB_REPLY
REL
RLC
Scenario 4 – Successful trunk call (cont.) Scenario 4 – Successful trunk call (cont.)
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
26
Summary Summary
Concept and function of H.248: As a bearer control protocol,
H.248 is used for communication between MGC and MG. The
protocol communication consists of terminations and
contexts.
There are multiple concepts for H.248, and the inclusion
relation in ascending order is as follows: descriptor –
command – action – transaction – message.
There are 6 commands: ADD, MODIFY, SUBSTRACT, MOVE,
AUDITVALUE, AUDITCAPABILLITIES, NOTIFY and
SERVICECHANGE.
The function of each command in H.248 call flow must be
mastered as the key point.
Confidential Information of Huawei. No Spreading without Permission.
Security Level: Internal
27