Internet DRAFT - draft-chenbo-enum-mgcp
draft-chenbo-enum-mgcp
ENUM -- Telephone Number Mapping Bo. Chen
Working Group Hui. Chen
Internet-Draft Xiaodong. Lee
Expires: January 10, 2008 Feng. Wang
CNNIC,China
July 9, 2007
Telephone Number Mapping (ENUM) Service Registration for MGCP
draft-chenbo-enum-mgcp-01.txt
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Copyright Notice
Copyright (C) The IETF Trust (2007).
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Abstract
MGCP decomposes a multimedia gateway into two parts, a call agent and
a media gateway,thus brings greater extensibility and makes it easy
to construct a large-scale VoIP network. This document registers the
MGCP Enumservice according to the guidelines given in RFC 3761.This
kind of Enumservice is mainly applied in Carrier Networks.
Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. ENUM Service Registration - MGCP . . . . . . . . . . . . . . . 5
4. Address of record in MGCP . . . . . . . . . . . . . . . . . . 6
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. The scenes for ENUM-MGCP application . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
9. DNS Considerations . . . . . . . . . . . . . . . . . . . . . . 12
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . 13
10.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
Intellectual Property and Copyright Statements . . . . . . . . . . 15
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1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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2. Introduction
E.164 Number Mapping (ENUM) [RFC3761] is a system that uses Domain
Name System (DNS) [RFC1035] to translate telephone numbers into
Uniform Resource Identifiers (URIs) [RFC3986]. By using DNS services
like delegation through NS records and NAPTR records, one can look up
what services are available for a specific E.164 numbers [E164].
As an improvement of H.323 [H323], MGCP [RFC3435] assumes a call
control architecture where the call control "intelligence" is outside
the gateways and handled by external call control elements MGC(Media
Gateway Controller)known as Call Agents, while MG(Media Gateway) is
just responsible for the media conversion. MGCP defines the
interaction messages between them. Moreover, MGCP assumes that these
call control elements, or Call Agents, will synchronize with each
other to send coherent commands and responses to the gateways under
their control because MGCP does not define a mechanism for
synchronizing Call Agents.
This document registers the MGCP Enumservice according to the
guidelines given in RFC3761 [RFC3761]. The MGCP Enumservice is used
in the services field of a NAPTR resource record which indicates what
class of functionality a given end point offers. As shown in
Section 6, ENUM-MGCP is mainly used in carrier networks, making a
unified addressing intra or inter MGCP system or even between other
VoIP systems and MGCP systems.
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3. ENUM Service Registration - MGCP
Enumservice Name: "MGCP"
Enumservice Type: "mgcp"
Enumservice Subtype: tel
URI Scheme: "tel:"
Functional Specification:
This document defines an 'E2U+mgcp:tel' Enumservice for MGCP. The
scheme of the URI that will appear in the regexp field of a NAPTR
record using the 'E2U+mgcp:tel' Enumservice is 'tel'.
Security Considerations: see Section 7
Intended Usage: COMMON
Authors: Bo. Chen, <chenbo@cnnic.cn> et al.
Any other information the authors deem interesting: None
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4. Address of record in MGCP
The address of MGCP end-points includes two parts. One is the domain
name of attributive gateway, the other is the local name of this
terminal in the gateway. Local name uses the form of physical
interface/circuit number. For example, MGCP address
hrd4/56@gw23.example.net:5060 means that the attributive gateway is
gw23.example.net, using port 5060, and the physical interface is hrd4
, while the circuit number is 56.
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5. Examples
An example ENUM record referencing to "MGCP" could look like:
$ORIGIN 9.2.1.3.1.8.8.5.0.1.6.8.e164.arpa.
@ IN NAPTR 10 100 "u" "E2U+mgcp:tel" "!^.*$!tel:hrd4/56@tst.cn!" .
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6. The scenes for ENUM-MGCP application
Part of MGCP's address of record is physical interface/circuit number
which should be unknown to end-users, so ENUM-MGCP is not for one
dedicated user but for carriers.With the help of ENUM-MGCP, the
calls, no matter intra MGCP system, inter MGCP system, or from other
VoIP systems, can have a unified addressing.
There are three scenes as below.In these scenes, T1 represents
terminal1,while T2 represents terminal2,and arrows show the call
signal.
Scene 1: the ENUM-based call procedure in the same MGCP system
MGC1 receives a call request from T1. After querying ENUM system,
MGC1 has found that the call would terminate in the same MGCP system,
then it makes a direct connection to MG12.
+------+ +--------+ +-------+
|MG11 | --------> | MGC1 | --------> | MG12 |
+------+ +--------+ +-------+
^ / ^ \
/ \
/ \
/ v \ v
+------+ +----------+ +-------+
| T1 | | ENUM | | T2 |
+------+ +----------+ +-------+
the ENUM-based call procedure in the same MGCP system
Scene 2: the ENUM-based call procedure among different MGCP systems
MGC1 receives a call request from T1. After querying from ENUM
system, MGC1 has found that the call would terminate in another MGCP
system, then it makes a connection to the relative call agent MGC2.
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+------+ +------+ +-----+ +-----+
|MG11 | ----> | MGC1 | -----> | MGC2| ---> |MG21 |
+------+ +------+ +-----+ +-----+
^ / ^ \
/ \
/ \
/ v \ v
+------+ +----------+ +-----+
| T1 | | ENUM | | T2 |
+------+ +----------+ +-----+
the ENUM-based call procedure among different MGCP systems
Scene 3: the ENUM-based call procedure between other VoIP systems and
MGCP systems
The call agent of other VoIP systems, such as sip or H.323 based
systems, receives a call request from T1. After ENUM query, it would
find that the caller is MGCP-based. It then makes a connection to
the attributive MGC using a MGCP-based signal.
+-----------+
+----+ | | +------+ +------+
| T1 | ------>| other VoIP| -----> | MGC | ----> | MG |
+----+ | H.323 sip | +------+ +------+
| | \
+-----------+
/ ^ \
\ v
/ +-----+
v \ | T2 |
+-----------+ +-----+
| ENUM |
+-----------+
the ENUM-based call procedure between other VoIP systems and MGCP
systems
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7. Security Considerations
As with any Enumservice, the security considerations of ENUM itself
(Section 6 of RFC 3761) apply. The security issues associated with
this Enumservice have not been assessed.
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8. IANA Considerations
This memo requests registration of the "MGCP" Enumservice with the
subtype "tel" according to the template Section 3 of this document
and RFC3761 [RFC3761]
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9. DNS Considerations
This Enumservices does not introduce any new considerations for the
DNS.
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10. References
10.1. Normative References
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3435] Andreasen, F. and B. Foster, "Media Gateway Control
Protocol (MGCP) Version 1.0", RFC 3435, January 2003.
[RFC3660] Foster, B. and F. Andreasen, "Basic Media Gateway Control
Protocol (MGCP) Packages", RFC 3660, December 2003.
[RFC3661] Foster, B. and C. Sivachelvan, "Media Gateway Control
Protocol (MGCP) Return Code Usage", RFC 3661,
December 2003.
[RFC3761] Faltstrom, P. and M. Mealling, "The E.164 to Uniform
Resource Identifiers (URI) Dynamic Delegation Discovery
System (DDDS) Application (ENUM)", RFC 3761, April 2004.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
10.2. Informative References
[E164] ITU-T, "The international public telecommunication
numbering plan", Recommendation E.164 (02/05), Feb 2005.
[H323] ITU-T, "Packet-based multimedia communications systems",
Recommendation H.323, 2003.
[RFC2705] Arango, M., Dugan, A., Elliott, I., Huitema, C., and S.
Pickett, "Media Gateway Control Protocol (MGCP) Version
1.0", RFC 2705, October 1999.
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Authors' Addresses
Bo,Chen
CNNIC,China
4 South 4th Street,Zhongguancun,Haidian District
Beijing 100080
China
Email: chenbo@cnnic.cn
Hui,Chen
CNNIC,China
4 South 4th Street,Zhongguancun,Haidian District
Beijing 100080
China
Email: chenhui@cnnic.cn
Xiaodong,Lee
CNNIC,China
4 South 4th Street,Zhongguancun,Haidian District
Beijing 100080
China
Email: lee@cnnic.cn
Feng,Wang
CNNIC,China
4 South 4th Street,Zhongguancun,Haidian District
Beijing 100080
China
Email: fengw@cnnic.cn
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