Internet Engineering Task Force Rajesh Kumar
Internet Draft Cisco Systems
Document: <draft-rajeshkumar-mgcp-atm-package-04.txt> May 2002
Category: Informational
Asynchronous Transfer Mode (ATM) Package for the Media Gateway Control Protocol
(MGCP)
Status of this Document
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet- Drafts.
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may be updated, replaced, or obsoleted by other documents at any time. It
is inappropriate to use Internet- Drafts as reference material or to cite
them other than as work in progress.
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
1.0 Abstract................................................................2
2.0 Conventions used in this document.......................................2
3.0 Introduction............................................................2
4.0 Local Connection Options................................................3
4.1 ATM bearer connection..................................................4
4.2 ATM adaptation layer (AAL).............................................8
4.3 Service layer.........................................................16
4.4 ATM bearer traffic management.........................................19
4.5 AAL Dimensioning......................................................28
5.0 Signals and Events......................................................30
6.0 Statistics..............................................................35
7.0 Negotiation of profiles and codecs in ATM applications..................37
7.1 Consistency of parameters............................................37
7.2 Codec/Profile negotiation in ATM networks...........................38
8.0 Security Considerations................................................44
9.0 References............................................................44
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10.0 Acronyms..............................................................46
11.0 Acknowledgements......................................................47
12.0 Author's Address.......................................................48
1.0 Abstract
This document describes an ATM package for the Media Gateway Control
Protocol (MGCP). This package includes new Local Connection Options, ATM-
specific events and signals, and ATM statistics parameters. Also included
is a description of codec and profile negotiation. As an informational
Internet-Draft, this document provides information for the Internet
community. It does not specify an Internet standard of any kind. It
extends the Media Gateway Control Protocol (MGCP) that is currently being
deployed in a number of products. Implementers should be aware of
developments in the IETF Megaco Working Group and ITU SG16, which are
currently working on a potential successor to this protocol.
2.0 Conventions used in this document
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.
MGCP identifiers are case-insensitive. This includes package names, event
names, local connection options and other elements of
the MGCP header.
3.0 Introduction
The Media Gateway Control Protocol or MGCP [36] is used to control voice
media gateways from external call control elements. Even though the bearer
network might be IP, ATM, TDM or a mix of these, MGCP is transported over
IP. Packages such as the MGCP CAS packages [38] are modular sets of
parameters such as connection options, signal, event and statistics
definitions that can be used to extend it into specific contexts. A
related, IP-based mechanism for the description of ATM connections [18]
has been generated by the IETF MMUSIC group. Due to the IP-centric nature
of all aspects of the MGCP device control protocol, and for consistency
with other MGCP package definitions, it is desirable to publish the MGCP
ATM package in an IETF document.
The ATM package in this document consists of Local Connection Options
(Section 4.0), Events and Signals (Section 5.0) and ATM Statistics
Parameters (Section 6.0). Section 7.1 has guidelines
for consistency in the use of Local Connection Options. Section
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7.2 describes codec and profile negotiation. Section 8.0 addresses
security considerations.
In the ATM networks addressed in this document, services are carried
directly over ATM without an intervening IP layer. The Local Connection
Options, Events, Signals and Statistics Parameters described in this
section are not needed for VoIP calls which can be carried, in whole or in
part, over an ATM network. In that case, the constructs defined elsewhere
for IP are sufficient.
The ATM local connection option names, event names and signal names
should always have an "atm" package prefix. Backward
compatibility with older implementations that use ôX-atmö
as the package name is desirable.
4.0 Local Connection Options
The Local Connection Options (LCOs) defined in this section are specific
to ATM applications. Like other Local Connection Options (LCOs), these can
be used in create connection, modify connection and audit connection
transactions. However, unless noted otherwise below, they are not to be
returned when an endpoint is audited for capabilities.
ATM Local Connection Options are divided into the following categories:
ATM bearer connection, ATM adaptation layer, service layer, ATM bearer
traffic management and AAL dimensioning.
When parameter values are represented in decimal format, leading zeros are
omitted.
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4.1 ATM bearer connection
These local connection options are used to parameterize ATM bearer
connections.
TABLE 1: Local Connection Options for ATM Bearers
+---------+---------------+---------------------------------------+
| LCO | Meaning | Values |
+---------+---------------+---------------------------------------+
| ct | Connection |AAL1, AAL1_SDT, AAL1_UDT, AAL2, AAL3/4,|
| | Type |AAL5, USER_DEFINED_AAL |
+---------+---------------+---------------------------------------+
| vc |VC/Bearer type | PVC, SVC, CID |
+---------+---------------+---------------------------------------+
| se | Enable path | on, off |
| | set-up | |
+---------+---------------+---------------------------------------+
| ci | Connection | See below |
| | Element | |
| | Identifier | |
+---------+---------------+---------------------------------------+
Connection type (ct): This parameter describes the ATM adaptation layer.
The values that can be assigned to it are: AAL1, AAL1_SDT, AAL1_UDT, AAL2,
AAL3/4, AAL5 and USER_DEFINED_AAL. The user defined adaptation layer is
per amendment 2 of ITU-T Q.2931.
Type of Bearer/VC (vc): This indicates whether a PVC, CID or an SVC is to
be used for an ATM connection. Possible values are: PVC, SVC or CID.
Omitting this parameter will result in the use of a default, which could
be embedded or provisioned. The value "PVC" covers both classical PVCs and
SPVCs. The value ôCIDö covers subchannels within AAL1 [35] and
subchannels within AAL1 [35] and AAL2 [10] virtual circuits.
While the parameter atm/vc describes bearer type, the parameter
atm/se (described below) requests the set-up of a bearer path.
A value of ôSVCö for atm/vc does not imply that the media
gateway should initiate signaling for bearer set-up, since
this might be done by another node such as the far-end media
gateway.
Enable path set-up (se): This local connection option is used to
explicitly enable or disable the use of bearer signaling for path set-up.
Permitted values of this local connection option are "on" and "off".
When this option is omitted, other means are used to determine if bearer
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signaling is to be used for path set-up. Examples of bearer signaling are
SVC signaling, ITU Q.2630.1 signaling and combinations thereof. Examples
of such combinations are the set-up of an AAL2 SVC and the assignment of a
CID within it or the set-up of a concatenation of an AAL2 single-CID SVC
and a CID channel within a multiplexed AAL2 VC. This parameter allows the
flexible support of both the backwards and forward bearer connection set-
up methods. In the former case, the call-terminating gateway sets up the
bearer connection. In the latter case, the call-originating gateway sets
up the bearer connection.
Connection Element Identifier (ci): This indicates the Virtual Circuit or
CID to be used for the bearer connection. It is used when the call agent
manages VC and/or CID resources in the bearer network.
The ci parameter can be in one of the following formats:
* VCCI-<vcci>
* VCCI-<vcci>/CID-<cid>
* <ATMaddressType>-<ATMaddress>/VCCI-<vcci>
* <ATMaddress>/VCCI-<vcci>
* <ATMaddressType>-<ATMaddress>/VCCI-<vcci>/CID-<cid>
* <ATMaddress>/VCCI-<vcci>/CID-<cid>
* BCG-<bcg>/VCCI-<vcci>
* BCG-<bcg>/VCCI-<vcci>/CID-<cid>
* BCG-<bcg>/VPI-<vpi>/VCI-<vci>
* BCG-<bcg>/VPI-<vpi>/VCI-<vci>/CID-<cid>
* PORT-<portId>/VPI-<vpi>/VCI-<vci>
* PORT-<portId>/VPI-<vpi>/VCI-<vci>/CID-<cid>
* VPCI-<vpci>/VCI-<vci>
* VPCI-<vpci>/VCI-<vci>/CID-<cid>
* <ATMaddressType>-<ATMaddress>/VPCI-<vpci>/VCI-<vci>
* <ATMaddress>/VPCI-<vpci>/VCI-<vci>
* <ATMaddressType>-<ATMaddress>/VPCI-<vpci>/VCI-<vci>/CID-<cid>
* <ATMaddress>/VPCI-<vpci>/VCI-<vci>/CID-<cid>
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The subparameters of the ci parameter are defined as follows:
|--------------|-----------------------|----------------------------|
| Subparameter | Meaning | Representation |
|--------------|-----------------------|----------------------------|
| vcci | VC connection Id | Decimal Integer |
| | | (16-bit equivalent) |
|--------------|-----------------------|----------------------------|
| cid | Channel Id | Decimal Integer |
| | | (8-bit equivalent) |
|--------------|-----------------------|----------------------------|
|ATMaddressType| ATM address type | "NSAP", "E164", "GWID", |
| | | "ALIAS" |
|--------------|-----------------------|----------------------------|
| ATMaddress | ATM address | 40 hex digits ("NSAP") |
| | | upto 15 digits ("EI64") |
| | | upto 32 chars ("GWID") |
| | | upto 32 chars ("ALIAS") |
|--------------|-----------------------|----------------------------|
| bcg |Bearer Connection Group| Decimal Integer |
| | | (8-bit equivalent) |
|--------------|-----------------------|----------------------------|
| vpi | Virtual Path Id | Decimal Integer |
| | | (8 or 12-bit equivalent) |
|--------------|-----------------------|----------------------------|
| vci | Virtual Channel Id | Decimal Integer |
| | | (16-bit equivalent) |
|--------------|-----------------------|----------------------------|
| portID | Port Id | Decimal Integer |
| | | (32-bit equivalent) |
|--------------|-----------------------|----------------------------|
| vpci | VP connection ID | Decimal Integer |
| | | (16-bit equivalent) |
|--------------|-----------------------|----------------------------|
The CID, or Channel ID, can refer to AAL1 as well as AAL2
applications. In AAL1 applications based on [35], it refers to
the octet position, starting from one, within an n x 64 SDT
frame.
The VPCI is a 16 bit field defined in Section 4.5.16 of ITU Q.2931. The
VPCI is similar to the VPI, except for its width and the fact that it
retains its value across VP crossconnects.
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The VCCI is a 16 bit field defined in ITU Recommendation Q.2941.2 [14].
The VCCI is similar to the VCI, except for the fact that it retains its
value across VC crossconnects.
In general, <vpci> and <vcci> values are unique between a pair of
nodes. When they are unique between a pair of nodes but not unique within
a network, they need to be qualified, at any node, by the ATM address of
the remote node. These parameters can be pre-provisioned or signaled via
SVC signaling messages. When VPCI and VCCI values are pre-provisioned,
administrations have the option of provisioning them uniquely in a
network. In this case, the ATM address of the far end is not needed to
qualify these parameters.
The <portId> parameter is used to identify the physical trunk port on an
ATM module. It can be represented as a decimal or hex number of up to 32
digits.
In some applications, it is meaningful to bundle a set of connections
between a pair of ATM nodes into a bearer connection
group. The <bcg> subparameter is an eight bit field that allows
the bundling of up to 255 VPCs or VCCs.
In some applications, it is necessary to wildcard some elements of the ci
local connection option. The "$" wildcard character can be substituted for
some of the terms of this parameter. While wildcarding, the constant
strings that qualify the terms in the ci parameter are retained. The
concatenation <ATMaddressType>-<ATMaddress> can be wildcarded in the
following ways:
* The entire concatenation, <ATMaddressType>-<ATMaddress>, is
replaced with a "$".
* <ATMaddress> is replaced with a "$", but <ATMaddressType> is
not.
Examples of wildcarding the ci parameter in the AAL1 and AAL5 contexts
are: VCCI-$, BCG-100/VPI-20/VCI-$.
Examples of wildcarding the ci parameter in the AAL2 context are: VCCI-
40/CID-$, BCG-100/VPI-20/VCI-120/CID-$.
If the addressType is NSAP, the address is expressed in the standard
dotted hex form. This is a string of 40 hex digits, with dots after the
2nd, 6th, 10th, 14th, 18th, 22nd, 26th, 30th, 34th and 38th digits. The
"0x" prefix is not used, since this is always represented in hex. The last
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octet of the NSAP address is the 'selector' field that is available for
non-standard use. For example:
L: atm/ci:NSAP-47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00/
VCCI-65
If the ATMaddressType is E164, the ATMaddress is expressed as a decimal
number with up to 15 digits. For example:
L: atm/ci:E164-9738294382/VCCI-100
The E.164 numbers used can be in the International Format E.164 or conform
to a private numbering plan.
If the ATMaddressType is GWID, it means that the address is a
Gateway Identifier or Node Alias. This may or may not be globally unique.
In this format, the ATMaddress is expressed as an alphanumeric string
("A"-"Z", "a"-"z", "0" - "9",".","-","_"). For example:
L: atm/ci:GWID-officeABCmgx101vism12
The keyword "ALIAS" can be substituted for "GWID". For example:
L: atm/ci:ALIAS-officeABCmgx101vism12
An example of a GWID (ALIAS)is the CLLI code used for telecom
equipment. For all practical purposes, it should be adequate for the
GWID (ALIAS) to be a variable length string with a maximum size of 32
characters.
When an endpoint supporting the ATM package is audited for capabilities,
the following local connection options from Section 4.1 shall be returned:
connection type (atm/ct) and VC/bearer type (atm/vc). If more than one
value is supported, these shall be expressed as a list of semicolon-
separated values. Although this is not very useful, it is permissible for
these values to have overlapping semantics (e.g. AAL1 and AAL1_SDT). An
example of returning, in audit response, the local connection options
defined in Section 4.1 is:
A: atm/ct:AAL1_SDT;AAL2, atm/vc:PVC;CID
4.2 ATM adaptation layer (AAL)
These local connection options are used to parameterize the ATM adaptation
layer (AAL). These are further classified as: generic AAL connection
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options, AAL1-related connection options and AAL2-related connection
options. Currently, there are no local connection options defined in this
category that pertain to AAL5.
TABLE 2: Generic Local Connection Options for the AAL
+---------+---------------+---------------------------------------+
| LCO | Meaning | Values |
+---------+---------------+---------------------------------------+
| aalApp | Application |itu_h323c,af83,AAL5_SSCOP, |
| | |itu_i3661_unassured, itu_i3661_assured |
| | |itu_i3662, itu_i3651, itu_i3652, |
| | |itu_i3653, itu_i3654, |
| | |FRF5, FRF8, FRF11,itu_h2221 |
+---------+---------------+---------------------------------------+
| sbc | Subchannel | 1...24 for T1-based applications |
| | Count | 1...31 for E1-based applications |
+---------+---------------+---------------------------------------+
AAL application (aalApp): This connection option specifies the controlling
standard for an application layer above the ATM adaptation layer. Other
strings can be defined. If used, these need to be prefixed with an "X-".
"itu_h323c" Annex C of H.323 which specifies direct
RTP on AAL5 [12].
"af83" af-vtoa-0083.001, which specifies
variable size AAL5 PDUs with PCM voice
and a null SSCS [13].
"AAL5_SSCOP" SSCOP as defined in ITU Q.2110 [14]
running over an AAL5 CPS [27].
No information is provided regarding
any layers above SSCOP such as Service
Specific Coordination Function (SSCF)
layers.
"itu_i3661_unassured" SSCS with unassured transmission,
per ITU I.366.1 [11].
"itu_i3661_assured" SSCS with assured transmission,
per ITU I.366.1 [11]. This uses SSCOP
[14].
"itu_i3662" SSCS per ITU I.366.2 [2].
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"itu_i3651" Frame relay SSCS per ITU I.365.1 [15].
"itu_i3652" Service-specific coordination function,
as defined in ITU I.365.2, for Connection
Oriented Network Service (SSCF-CONS)
[16]. This uses SSCOP [14].
"itu_i3653" Service-specific coordination function,
as defined in ITU I.365.3, for Connection
Oriented Transport Service (SSCF-COTS)
[17]. This uses SSCOP [14].
"itu_i3654" Service-specific coordination function,
as defined in ITU I.365.4 [28].
"FRF5" Use of the FRF.5 frame relay standard
[23], which references ITU I.365.1 [15].
"FRF8" Use of the FRF.8 frame relay standard
[24]. This implies a null SSCS and the
mapping of the frame relay header
into the ATM header.
"FRF11" Use of the FRF.11 frame relay standard
[25].
"itu_h2221" Use of the ITU standard H.222.1 for
audiovisual communication over AAL5
[22].
Subchannel count (sbc): This parameter indicates the number of DS0s in an
n x 64 connection. Such connections use an ATM adaptation layer 1 (ATM
forum af-vtoa-78) or 2 (ITU I.366.2). For T1-based applications, it can
take on integral values in the inclusive range [1...24]. For E1-based
applications, it can take on integral values in the inclusive range
[1...31]. When this parameter is omitted, the subchannel count must be
known by other means.
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TABLE 3: Local Connection Options for AAL Type 1
+---------+---------------+---------------------------------------+
| LCO | Meaning | Values |
+---------+---------------+---------------------------------------+
| pf | Partial fill | 1...48 |
| | | |
+---------+---------------+---------------------------------------+
| crt | Clock Recovery| NULL, SRTS, ADAPTIVE |
| | Type | |
+---------+---------------+---------------------------------------+
| fe | FEC enable | NULL, DELAY_SENSITIVE,LOSS_SENSITIVE |
+---------+---------------+---------------------------------------+
Partial Fill Count (pf): When present, the 'pf' parameter is used to
indicate the fill level of cells. When this local connection option is
absent, then other means (such as provisionable defaults) are used to
determine the presence and level of partial fill.
This parameter indicates the number of non-pad payload octets, not
including any AAL SAR or convergence sublayer octets. For example, in some
AAL1 applications that use partially filled cells with padding at the end,
this attribute indicates the number of leading payload octets not
including any AAL overhead.
In general, permitted values of the pf parameter are integers in the
range 1 - 48 inclusive. However, this upper bound is different for
different adaptations since the AAL overhead, if any, is different. If the
specified partial fill is greater than or equal to the maximum fill, then
complete fill is used. Using a 'partial' fill of 48 always disables
partial fill.
In the AAL1 context, this parameter applies uniformly to both P and non-P
cells. In AAL1 applications that do not distinguish between P and non-P
cells, a value of 47 indicates complete fill (i.e. the absence of partial
fill). In AAL1 applications that distinguish between P and non-P cells, a
value of 46 indicates no padding in P-cells and a padding of one in non-P
cells.
If partial fill is enabled (i.e there is padding in at least some cells),
then AAL1 structures must not be split across cell boundaries. These shall
fit in any cell. Hence, their size shall be less than or equal to the
partial fill size. Further, the partial fill size is preferably an
integer multiple of the structure size. If not, then the partial fill size
stated in the local connection options shall be truncated to an integer
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multiple of the structure size (e.g. a partial fill size of 40 is
truncated to 36 to support six 6 x 64 channels).
Clock recovery type (crt): This is used in AAL1 UDT (unstructured data
transfer) applications only. It can be assigned the values: "NULL",
"SRTS", or "ADAPTIVE". A value of "NULL" is equivalent to omitting this
parameter and implies that the stream (T1 or E1) encapsulated in ATM is
either synchronous to the ATM network or is re-timed, before AAL1
encapsulation, via slip buffers. The default value used in the absence of
this LCO can be hardcoded or provisioned.
Forward Error Correction Enable (fe): This indicates whether FEC, as
defined in ITU I.363.1 [1], is enabled or not. Possible values are:
"NULL", "DELAY_SENSITIVE" and "LOSS_SENSITIVE". FEC can be enabled
differently for delay-sensitive and loss-sensitive connections. A "NULL"
value implies disabling FEC for an AAL1 connection.
TABLE 4: Local Connection Options for AAL Type 2
+---------+---------------+---------------------------------------+
| LCO | Meaning | Values |
+---------+---------------+---------------------------------------+
| pfl | Profile List | See below |
| | | |
+---------+---------------+---------------------------------------+
| smplCPS | Simplified CPS| on, off |
| | [21] | |
+---------+---------------+---------------------------------------+
| tmcu | Combined use | Integer microseconds |
| | timer | (32-bit equivalent) |
+---------+---------------+---------------------------------------+
| aalsap |Service access | AUDIO, MULTIRATE |
| |point | |
+---------+---------------+---------------------------------------+
| cktmd | Circuit mode | on, off |
| | | |
+---------+---------------+---------------------------------------+
| frmd | Frame mode | on,off |
| | enable | |
+---------+---------------+---------------------------------------+
| genpcm | Generic PCM | PCMA, PCMU |
| | setting | |
+---------+---------------+---------------------------------------+
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+---------+---------------+---------------------------------------+
| ted | Transmission | on,off |
| |error detection| |
+---------+---------------+---------------------------------------+
|rastimer | SSSAR | |
| | reassembly | Integer microseconds |
| | timer | (32-bit equivalent) |
+---------+---------------+---------------------------------------+
Profile List (pfl): This is a list of profiles. Profile types are followed
by profile numbers for each type. The ordering of profiles can imply
preference, with the most preferred profile first. There can be multiple
instances of the same profile type in this list.
The format of the pfl parameter is as follows:
<profileType#1><format list#1><profileType#2><format list#2> ...
<profileType #M><format list#M>
where <format list#i> has the form <profile#i_1>...<profile#i_N>
The <profileType> parameter indicates the type of profile. It is expressed
in the format AAL2/<profileClass> where <profileClass> identifies the
source of the definition of the profile.
The <profileClass> can be assigned a string value indicating the source
of the subsequent profile numbers until the next <profileType> field. The
following rules apply to the contents of the <profileClass> field:
- <profileClass> = "ITU" indicates profiles defined by ITU.
Examples: profiles defined in the I.366.2 specification [2].
- <profileClass> = "ATMF" indicates profiles defined by ATM
forum. Examples: profiles defined in af-vtoa-0113 [3]
or af-vmoa-0145.000 [21].
- <profileClass> = "custom" indicates profiles defined by a
corporation or a multi-vendor agreement. Since there is no
standard administration of this convention, care should be taken
to preclude inconsistencies within the scope of a deployment.
- <profileClass> = <corporateName>
An equipment vendor or service provider can use its registered,
globally unique corporate name (e.g. Cisco, Telcordia etc.) as a
string value of the <profileClass>. It is suggested that
organizations maintain consistent definitions of the advertised
AAL2 profiles that bear their corporate name.
- The <profileClass> can be based on IEEE Standard 802-1990,
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Section 5.1, which defines the globally unique, IEEE-
administered, three-octet OUIs used in MAC addresses and protocol
identifiers. In this case, the <profileClass> field shall be
assigned a string value of "IEEE:" concatenated with <oui> where
<oui> is the hex representation of a three-octet field identical
to the IEEE OUI. Since this is always represented in hex, the
"0x" prefix is not used. Leading zeros may be omitted. For
example, "IEEE:00000C" and "IEEE:C" both refer to Cisco Systems,
Inc.
The <profile#> parameter is expressed as a decimal number in the range 1-
255.
An example of the use of the pfl parameter is:
L: atm/pfl:AAL2/ITU 8 AAL2/ATMF 7 8 AAL2/custom 100 AAL2/cisco 200
The syntax for pfl can be represented compactly in the following ABNF
(rfc2234) form:
pfl = 1*(profileType (1*profile#))
profileType = "AAL2/" profileClass space
profile# = 1-255 space ; decimal integer followed by space
profileClass =
"ATMF"/"ITU"/"custom"/corporateName/("IEEE:" oui)
corporateName = 1*ALPHA ;one or more alphanumeric characters
oui = 1*6 HEXDIG; 1-6 hex digits per IEEE Standard 802-1990
space = %d32
Simplified CPS (smplCPS): This enables the AAL2 CPS simplification
described in [21]. It can be assigned the following values: on, off. Under
this simplification, each ATM cell contains exactly on AAL2 packet. If
necessary, octets at the end of the cell are padded with zeros.
AAL2 combined use timer (tmcu): This is defined in ITU I.363.2 [10]. It is
an integer number of microseconds, represented as the decimal equivalent
of 32 bits.
AAL service access point (aalsap): The service access point for AAL2 is
defined in ITU I.366.2 [2]. The aalsap local connection option can take on
the following string values: AUDIO, MULTIRATE.
Circuit mode (cktmd): This is used to enable circuit mode data [2]. It
can be assigned a value of "on" or "off".
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Frame mode (frmd): This is used to enable frame mode data [2]. It can be
assigned a value of "on" or "off".
Generic PCM setting (genpcm): This indicates whether generic PCM encoding
in AAL2 profiles is A-law or Mu-law. It can be assigned the string values
of "PCMA" and "PCMU".
Transmission error detection (ted): Transmission error detection is
defined in ITU I.366.1 [11]. The ted local connection option can take on
the following values: on, off. This local connection option is useful in
qualifying the aalApp local connection option, when the value of the
latter is "itu_i3661_unassured".
SSSAR reassembly timer (rastimer): This is defined in ITU I.366.1 [11]. It
is an integer number of microseconds, represented as the decimal
equivalent of 32 bits.
When an endpoint supporting the ATM package is audited for capabilities,
the following local connection options from Section 4.2 shall be
returned: application (atm/aalApp). Further, if one of the values atm/ct
is "AAL2", the following additional local connection options shall be
returned: profile list (atm/pfl), simplified CPS (atm/smplCPS), service
access point (atm/aalsap), circuit mode enable(atm/cktmd), frame mode
enable (atm/frmd) and generic PCM setting (atm/genpcm). If more than one
value is supported, these shall be expressed as a list of semicolon-
separated values. For atm/smplCPS, atm/cktmd and atm/frmd, an audit can
return "on", "off" or "on;off" depending on whether the mode is mandatory,
unsupported or optional for the endpoint.
An example of returning, in audit response, the local connection options
defined in Section 4.2 is:
A: atm/aalApp:itu_i3662, atm/pfl: AAL2/ATMF 7 8, smplCPS:on;off,
aalsap: MULTIRATE, cktmd:off, frmd:off, genpcm:PCMU;PCMA,
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4.3 Service layer
TABLE 5: Local Connection Options for the Service Layer
+--------------+---------------+----------------------------------+
| LCO | Meaning | Values |
+--------------+---------------+----------------------------------+
| vsel | Voice codec | See below |
| | Selection | |
+--------------+---------------+----------------------------------+
| dsel | Data codec | See below |
| | Selection | |
+--------------+---------------+----------------------------------+
| fsel | Fax codec | See below |
| | Selection | |
+--------------+---------------+----------------------------------+
| ccnf | Codec | Even number (4 - 32) hex digits |
| | Configuration | |
+--------------+---------------+----------------------------------+
| usi | ISUP User | Two hex digits |
| | Information | |
+--------------+---------------+----------------------------------+
Voice codec selection (vsel): This is a prioritized list of one or more 3-
tuples describing voice service. Each vsel 3-tuple indicates a codec, an
optional packet length and an optional packetization period. The vsel
local connection option is structured as follows:
<encodingName #1> <packetLength #1><packetTime #1>
<encodingName #2> <packetLength #2><packetTime #2>
...
<encodingName #N> <packetLength #N><packetTime #N>
where the <encodingName> refers to a codec name such as PCMU, G726-32,
G729 etc. See [18] and [34] for a list of codecs with static payload
types. The <packetLength> is a decimal integer representation of the
packet length in octets. The <packetTime> is a decimal integer
representation of the packetization interval in microseconds.
Voiceband data codec selection (dsel): This is a prioritized list of one
or more 3-tuples describing voiceband data service. Each dsel 3-tuple
indicates a codec, an optional packet length and an optional packetization
period. Depending on the application, the dsel local connection option may
or may not cover facsimile service. This is indicated via an <fxIncl> flag
preceding the list of 3-tuples. This flag indicates whether the definition
of voiceband data includes facsimile ("on" value) or not ("off" value).
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This flag can also be set to "-", which is equivalent to setting it to
"off". If <fxIncl> is "on", then the dsel connection option must be
consistent the fsel connection option. The dsel local connection option is
structured as follows:
<fxIncl> <encodingName #1> <packetLength #1><packetTime #1>
<encodingName #2> <packetLength #2><packetTime #2>
...
<encodingName #N> <packetLength #N><packetTime #N>
where the <encodingName> refers to a codec name such as PCMU, G726-32,
G729 etc. The <packetLength> is a decimal integer representation of the
packet length in octets. The <packetTime> is a decimal integer
representation of the packetization interval in microseconds.
Facsimile codec selection (fsel): This is a prioritized list of one or
more 3-tuples describing fax service. Each fsel 3-tuple indicates a codec,
an optional packet length and an optional packetization period. If the
dsel option includes facsimile, the fsel connection option should be
consistent with it. Each fsel 3-tuple indicates a codec, an optional
packet length and an optional packetization period. The fsel local
connection option is structured as follows:
<encodingName #1> <packetLength #1><packetTime #1>
<encodingName #2> <packetLength #2><packetTime #2>
...
<encodingName #N> <packetLength #N><packetTime #N>
where the <encodingName> refers to a codec name such as PCMU, G726-32,
G729 etc. The <packetLength> is a decimal integer representation of the
packet length in octets. The <packetTime> is a decimal integer
representation of the packetization interval in microseconds.
The vsel, fsel and dsel parameters complement the rest of the local
connection options and should be consistent with them.
Examples of the use of these parameters are:
L: atm/vsel:G729 10 10000 G726-32 40 10000
L: atm/dsel:off PCMA 10 10000 G726-32 40 10000
L: atm/fsel:PCMU 40 5000 G726-32 20 5000
L: atm/vsel:G729 10 10000 G726-32 40 10000
L: atm/dsel:on PCMA 10 10000 G726-32 40 10000
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The <packetLength>and <packetTime> can be set to "-" when not needed. A
<fxIncl> value of "-" is equivalent to setting it to "off". For example:
L: atm/vsel:G729 - - G726-32 - -
L: atm/dsel:- G729 - - G726-32 - -
L: atm/fsel:FXDMOD-3 - -
The vsel, dsel and fsel local connection options can be used in the AAL1,
AAL2 and AAL5 contexts. The <packetLength> and <packetTime> are not
meaningful in the AAL1 case and should be set to "-". In the AAL2 case,
these local connection options indicate the preferred use of some or all
of the rows in a given profile table. If multiple 3-tuples are present,
they can indicate a preferentially ordered assignment of some rows in that
profile to voice, voiceband data or facsimile service e.g. row A preferred
to row B etc. If multiple profiles are specified in the pfl parameter
(described in section 4.2), the profile qualified by these local
connection options is the first profile in the list.
Codec configuration (ccnf): This is used to convey the contents of the
single codec information element (IE) defined in [30]. The contents of
this IE are: a single-octet Organizational Identifier (OID) field,
followed by a single-octet Codec Type field, followed by zero or more
octets of a codec configuration bit-map. The semantics of the codec
configuration bit-map are specific to the organization[30, 31]. Since this
bit-map is always represented in hex format, the "0x" prefix is omitted.
Leading zeros are not omitted. For example:
L: atm/ccnf:01080C
indicates an Organizational Identifier of 0x01(the ITU-T). Using [57], the
second octet (0x08) indicates a codec type of G.726 (ADPCM). The last
octet, 0x0C indicates that 16 kbps and 24 kbps rates are NOT supported,
while the 32 kbps and 40 kbps rates ARE supported.
ISUP User Information (usi): This is used to convey the contents of the
'User Information Layer 1 protocol' field within the bearer capability
information element defined in Section 4.5.5 of [32], and reiterated as
the user service information element (IE) in Section 3.57 of [33]. The
'User Information Layer 1 protocol' field consists of the five least
significant bits of Octet 5 of this information element.
The usi LCO represented as a string of two hex digits. The "0x"prefix is
omitted since this value is always hexadecimal. These hex digits are
constructed from an octet with three leading '0' bits and last five bits
equal to the 'User Information Layer 1 protocol' field described above.
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Digits to the left are more significant than digits to the right. The
resulting values of the usi local connection option are as follows:
VALUE MEANING
0x01 CCITT standardized rate adaption V.110 and X.30
0x02 Recommendation G.711 Mu-law
0x03 Recommendation G.711 A-law
0x04 Recommendation G.721 32 kbps ADPCM
and Recommendation I.460
0x05 Recommendations H.221 and H.242
0x06 Recommendation H.223 and H.245
0x07 Non-ITU-T standardized rate adaption
0x08 ITU-T standardized rate adaption V.120
0x09 CCITT standardized rate adaption X.31 HDLC flag stuffing
4.4 ATM bearer traffic management
These local connection options are used to convey ATM traffic parameters.
TABLE 6: Local Connection Options for ATM bearer traffic management
+---------+---------------+---------------------------------------+
| ATM LCO | Meaning | Values |
+---------+---------------+---------------------------------------+
| atc | ATM transfer |CBR, nrt-VBR, rt-VBR, UBR, ABR, GFR, |
| | capability or |DBR,SBR,ABT/IT,ABT/DT |
| | service | |
| | category | |
+---------+---------------+---------------------------------------+
| sbt |atc subtype | 1...5 |
+---------+---------------+---------------------------------------+
| qos | QoS class | 0...5 |
+---------+---------------+---------------------------------------+
| bcob |Broadband | 0...31 |
| |Connection |(Defined values listed below) |
| |-Oriented | |
| |Bearer Class | |
+---------+---------------+---------------------------------------+
| eetim |End-to-end |on,off |
| |timing required| |
+---------+---------------+---------------------------------------+
| stc |Susceptibility | 0...3 |
| |to clipping |(Defined values listed below) |
+---------+---------------+---------------------------------------+
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+---------+---------------+---------------------------------------+
| upcc |User plane |0...3 |
| |connection |(Defined values listed below) |
| |configuration | |
+---------+---------------+---------------------------------------+
| aqf |ATM QoS | List, see below |
| |parameters, | |
| |forward | |
| |direction | |
+---------+---------------+---------------------------------------+
| aqb |ATM QoS | List, see below |
| |parameters, | |
| |backward | |
| |direction | |
+---------+---------------+---------------------------------------+
| adf0+1 |ATM traffic | List, see below |
| |descriptor, | |
| |forward | |
| |direction, | |
| |CLP-independent| |
+---------+---------------+---------------------------------------+
| adf0 |ATM traffic | List, see below |
| |descriptor, | |
| |forward | |
| |direction, | |
| |CLP=0 | |
+---------+---------------+---------------------------------------+
| adb0+1 |ATM traffic | List, see below |
| |descriptor, | |
| |backward | |
| |direction, | |
| |CLP-independent| |
+---------+---------------+---------------------------------------+
| adb |ATM traffic | List, see below |
| |descriptor, | |
| |backward | |
| |direction, | |
| |CLP=0 | |
+---------+---------------+---------------------------------------+
| abrf |ABR parameters,| List, see below |
| |forward | |
| |direction | |
+---------+---------------+---------------------------------------+
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+---------+---------------+---------------------------------------+
| abrb |ABR parameters,| List, see below |
| |backward | |
| |direction | |
+---------+---------------+---------------------------------------+
|abrSetup |ABR connection | List, see below |
| |set-up | |
| |parameters | |
+---------+---------------+---------------------------------------+
ATM transfer capability (atc): This parameter indicates the ATM Transfer
Capability described in ITU I.371 [19], equivalent to the ATM Service
Category described in the UNI 4.1 Traffic Management specification [8]. In
applications conforming to ITU I.371, this parameter can be assigned the
following values: DBR, SBR, ABT/IT, ABT/DT, ABR. In applications
conforming to the UNI 4.1 Traffic Management specification, this parameter
can be assigned the following values: CBR, nrt-VBR, rt-VBR, UBR, ABR, GFR.
Subtype (sbt): This qualifies the atc local connection option. It can be
assigned integer values of 1...5. The following combinations of the atc
and sbt local connection options are meaningful:
atc sbt Resulting transport
CBR/DBR 1 Voiceband signal transport (ITU G.711, G.722, I.363)
CBR/DBR 2 Circuit transport (ITU I.363)
CBR/DBR 4 High-quality audio signal transport (ITU I.363)
CBR/DBR 5 Video signal transport (ITU I.363)
nrt-VBR 1 nrt-VBR.1
nrt-VBR 2 nrt-VBR.2
nrt-VBR 3 nrt-VBR.3
rt-VBR 1 rt-VBR.1
rt-VBR 2 rt-VBR.2
rt-VBR 3 rt-VBR.3
UBR 1 UBR.1
UBR 2 UBR.2
GFR 1 GFR.1
GFR 2 GRR.2
SBR 1 SBR1
SBR 2 SBR2
SBR 3 SBR3
Subtypes for the atc values of CBR or DBR are per [29]. Subtypes for the
remaining atc values are per [8] and [19].
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QoS class (qos): This indicates the QoS class specified in ITU I.2965.1
[4]. It can take on the integer decimal values in the range 0 - 5. These
values are mapped into QoS classes as follows:
----------------------------------------------------------
| VALUE | MEANING |
----------------------------------------------------------
| 0 | Default QoS |
----------------------------------------------------------
| 1 | Stringent |
----------------------------------------------------------
| 2 | Tolerant |
----------------------------------------------------------
| 3 | Bi-level |
----------------------------------------------------------
| 4 | Unbounded |
----------------------------------------------------------
| 5 | Stringent bi-level |
----------------------------------------------------------
Broadband Connection-Oriented Bearer Class (bcob): The bcob local
connection option indicates the Broadband Connection-Oriented Bearer Class
specified in ITU Q.2961.2 [5]. It is represented as a decimal number in
the range 0 - 31, or its hex equivalent (range 0x0 - 0x1F). The following
values are currently defined:
----------------------------------------------------------
| VALUE | MEANING |
----------------------------------------------------------
| 1 | BCOB-A |
----------------------------------------------------------
| 3 | BCOB-C |
----------------------------------------------------------
| 5 | Frame relaying bearer service |
----------------------------------------------------------
| 16 | BCOB-X |
----------------------------------------------------------
| 24 | BCOB-VP (transparent VP service) |
----------------------------------------------------------
End-to-end timing (eetim): This indicates whether end-to-end timing is
required (Table 4-8 of [29]). It can be assigned a value of "on" or
"off".
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Susceptibility to clipping (stc): The stc local connection option
indicates susceptibility to clipping. It is represented as a decimal
number in the range 0 - 3, or its hex equivalent (range 0x0 - 0x3). All
values except those listed below are reserved.
----------------------------------------------------------
| VALUE | MEANING |
----------------------------------------------------------
| 0 | Not susceptible to clipping |
----------------------------------------------------------
| 1 | Susceptible to clipping |
----------------------------------------------------------
User plane connection configuration (upcc): The upcc local connection
option is represented as a decimal number in the range 0 - 3, or its hex
equivalent (range 0x0 - 0x3). All values except those listed below are
reserved.
----------------------------------------------------------
| VALUE | MEANING |
----------------------------------------------------------
| 0 | Point to point |
----------------------------------------------------------
| 1 | Point to multipoint |
----------------------------------------------------------
ATM QoS parameters, forward direction (aqf) and backward direction (aqb):
Here, forward is the direction away from the media gateway, backward is
the direction towards the gateway. If the directional convention used by
bearer signaling at the gateway is different, then appropriate
translations must be done by the media gateway. These parameters have the
following format:
<cdvType><acdv><ccdv><eetd><cmtd><aclr>
The <cdvType> parameter can take on the string values of "PP" and "2P".
These refer to the peak-to-peak and two-point CDV as defined in UNI 4.0
[6] and ITU Q.2965.2 [7] respectively.
The CDV parameters, <acdv> and <ccdv>, refer to the acceptable and
cumulative CDVs respectively. These are expressed in units of
microseconds and represented as the decimal or hex equivalent of 24-bit
fields. These use the cell loss ratio, <aclr>, as the "alpha" quantiles
defined in the ATMF TM 4.1 specification [8] and in ITU I.356 [9].
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The transit delay parameters, <eetd> and <cmtd>, refer to the end-to-
end and cumulative transit delays respectively in milliseconds. These
are represented as the decimal equivalents of 16-bit fields. These
parameters are defined in Q.2965.2 [7], UNI 4.0 [8] and Q.2931 [29].
The <aclr> parameter refers to forward and backward acceptable cell loss
ratios. This is the ratio between the number of cells lost and the number
of cells transmitted. It is expressed as the decimal or hex equivalent of
an 8-bit field. This field expresses an order of magnitude n, where n is
an integer in the range 1-15. The Cell Loss Ratio takes on the value 10
raised to the power of minus n.
If any of these parameters is not specified, is inapplicable or is
implied, then it is set to "-".
Examples of the use of the aqf and aqb local connection options are:
L: atm/aqf:PP 8125 3455 32000 - 11
L: atm/aqb:PP 4675 2155 18000 - 12
This implies a forward acceptable peak-to-peak CDV of 8.125 ms, a
backward acceptable peak-to-peak CDV of 4.675 ms, forward cumulative
peak-to-peak CDV of 3.455 ms, a backward cumulative peak-to-peak CDV
of 2.155 ms, a forward end-to-end transit delay of 32 ms, a backward
end-to-end transit delay of 18 ms, an unspecified forward cumulative
transit delay, an unspecified backward cumulative transit delay, a forward
cell loss ratio of 10 raised to minus 11 and a backward cell loss ratio
of 10 to the minus 12.
ATM traffic descriptors, forward direction CLP=0+1 (adf0+1), backward
direction CLP=0+1 (adb0+1), forward direction CLP=0 (adf0), backward
direction CLP=0 (adb0): Here, forward is the direction away from the media
gateway, backward is the direction towards the gateway. If the directional
convention used by bearer signaling at the gateway is different, then
appropriate translations must be done by the media gateway. The adf0+1,
adb0+1, adf0 and adb0 local connection options have the following format:
<pcr><scr><mbs><cdvt><mcr><mfs><fd><te>
These parameters are defined per the ATMF TM 4.1 specification [8]. Each
of these parameters can be set to "-" if the intent is to not specify it
via MGCP. These definitions are listed briefly in Table 7 below.
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TABLE 7: ATM Traffic Descriptor Parameters
PARAMETER MEANING UNITS
pcr Peak Cell Rate Cells per second
scr Sustained Cell Rate Cells per second
mbs Maximum Burst Size Cells
cdvt Cell Delay Variation Tolerance Microseconds
mcr Minimum Cell Rate Cells per second
mfs Maximum Frame Size Cells
fd Frame Discard Allowed on/off
te CLP tagging enabled on/off
The pcr, scr, cdvt and mbs can be represented as the decimal equivalents
of 24-bit fields. The mbs and mfs can be represented as the decimal
equivalents of 16-bit fields.
Examples of these local connection options are:
L: atm/adf0+1:200 100 20 - - - on -,
atm/adf0:200 80 15 - - - - off,
atm/adb0+1:200 100 20 - - - on -,
atm/adb0:200 80 15 - - - - off
This implies a forward and backward PCR of 200 cells per second
all cells regardless of CLP, forward and backward PCR of 200 cells
per second for cells with CLP=0, a forward and backward SCR of 100
cells per second for all cells regardless of CLP, a forward and
backward SCR of 80 cells per second for cells with CLP=0,
a forward and backward MBS of 20 cells for all cells regardless
of CLP, a forward and backward MBS of 15 cells for cells with
CLP=0, an unspecified CDVT which can be known by other means,
and an MCR and MFS which are unspecified because they are
inapplicable. Frame discard is enabled in both the forward and
backward directions. Tagging is not enabled in either direction.
ABR parameters, forward direction (abrf) and backward direction (abrb):
Here, forward is the direction away from the media gateway, backward is
the direction towards the gateway. If the convention used by bearer
signaling at the gateway is different, then appropriate translations must
be done by the media gateway. The abrf and abrb local connection options
have the following format:
<nrm><trm><cdf><adtf>
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These are defined per [6] and [8]. Their definition is summarized in Table
8 below. In MGCP, these are represented as the decimal equivalent of the
binary fields mentioned below. If any of these parameters is meant to be
left unspecified, it is set to "-".
TABLE 8: ABR Parameters
+-----------+---------------------------------+-----------------------+
| PARAMETER | MEANING | FIELD SIZE |
+-----------+---------------------------------+-----------------------+
| NRM | Maximum number of cells per | 3 bits |
| | forward Resource Management cell| |
+-----------+---------------------------------+-----------------------+
| TRM | Maximum time between | 3 bits |
| |forward Resource Management cells| |
+-----------+---------------------------------+-----------------------+
| CDF | Cutoff Decrease Factor | 3 bits |
+-----------+---------------------------------+-----------------------+
| ADTF | Allowed Cell Rate Decrease | 10 bits |
| | Time Factor | |
+-----------+---------------------------------+-----------------------+
ABR set-up parameters (abrSetup): This local connection option is used to
indicate the ABR parameters needed during call/connection establishment
(Section 10.1.2.2 of the UNI 4.0 signaling specification [6]). The
abrSetup local connection option has the following format:
<ficr><bicr><ftbe><btbe><crmrtt><frif><brif><frdf><brdf>
These parameters are defined per [6]. Their definitions are listed
briefly in Table 9 below. In these definitions, forward is the direction
away from the media gateway, backward is the direction towards the
gateway. If the convention used by bearer signaling at the gateway is
different, then appropriate translations must be done by the media
gateway. If any of these parameters is meant to be left unspecified, it is
set to "-".
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TABLE 9: ABR Set-up Parameters
+-----------+----------------------------------+---------------------+
| PARAMETER | MEANING | REPRESENTATION |
+-----------+----------------------------------+---------------------+
| <ficr> | Forward Initial Cell Rate | Decimal equivalent |
| |(Cells per second) | of 24-bit field |
+-----------+----------------------------------+---------------------+
| <bicr> | Backward Initial Cell Rate | Decimal equivalent |
| | (Cells per second) | of 24-bit field |
+-----------+----------------------------------+---------------------+
| <ftbe> | Forward transient buffer | Decimal equivalent |
| | exposure (Cells) | of 24-bit field |
+-----------+----------------------------------+---------------------+
| <btbe> | Backward transient buffer | Decimal equivalent |
| | exposure (Cells) | of 24-bit field |
+-----------+----------------------------------+---------------------+
| <crmrtt> | Cumulative RM round-trip time | Decimal equivalent |
| | (Microseconds) | of 24-bit field |
+-----------+----------------------------------+---------------------+
| <frif> | Forward rate increase factor | Decimal integer |
| | (used to derive cell count) | 0 -15 |
+-----------+----------------------------------+---------------------+
| <brif> | Backward rate increase factor | Decimal integer |
| | (used to derive cell count) | 0 -15 |
+-----------+----------------------------------+---------------------+
| <frdf> | Forward rate decrease factor | Decimal integer |
| | (used to derive cell count) | 0 -15 |
+-----------+----------------------------------+---------------------+
| <brdf> | Backward rate decrease factor | Decimal integer |
| | (used to derive cell count) | 0 -15 |
+-----------+----------------------------------+---------------------+
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4.5 AAL Dimensioning
The Local Connection Options in Table 10 are used to dimension the
operation of the AAL. In these parameters, forward is the direction away
from the media gateway. Backward is the direction towards the media
gateway. These parameters are represented as decimal integers in the
ranges listed in Table 10.
TABLE 10: Local Connection Options used to dimension the AAL
+---------+---------------+---------------------------------------+
| LCO | Meaning | Values (Decimal Integer) |
+---------+---------------+---------------------------------------+
| str | Structure | 1...65,535 |
| | Size | |
+---------+---------------+---------------------------------------+
| cbrRate | CBR rate | Bit map per Table 4-6 of [29] |
+---------+---------------+---------------------------------------+
| fcpcs | Forward | AAL2: 45 or 64 |
| | maximum CPCS | AAL5: 1-65,535 |
| | SDU size | |
+---------+---------------+---------------------------------------+
| bcpcs | Backward | AAL2: 45 or 64 |
| | maximum CPCS | AAL5: 1-65,535 |
| | SDU size | |
+---------+---------------+---------------------------------------+
|fSDUrate | Forward | 24-bit equivalent |
| | maximum AAL2 | |
| | CPS SDU rate | |
+---------+---------------+---------------------------------------+
|bSDUrate | Backward | 24-bit equivalent |
| | maximum AAL2 | |
| | CPS SDU rate | |
+---------+---------------+---------------------------------------+
| ffrm |Forward maximum| 1-65,535 |
| |frame block | |
| |size | |
+---------+---------------+---------------------------------------+
| bfrm |Backward | 1-65,535 |
| |maximum frame | |
| |block size | |
+---------+---------------+---------------------------------------+
|fsssar |Forward maximum| 1-65,568 |
| |SSSAR-SDU | |
| |size | |
+---------+---------------+---------------------------------------+
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+---------+---------------+---------------------------------------+
|bsssar |Backward | 1-65,568 |
| |maximum SSSAR | |
| |SDU size | |
+---------+---------------+---------------------------------------+
|fsscopsdu|Forward maximum| 1-65,528 |
| |SSCOP-SDU | |
| |size | |
+---------+---------------+---------------------------------------+
| | | |
|bsscopsdu|Backward | 1-65,528 |
| |maximum SSCOP | |
| |SDU size | |
+---------+---------------+---------------------------------------+
|fsscopuu |Forward maximum| 1-65,524 |
| |SSCOP-UU field | |
| |size | |
+---------+---------------+---------------------------------------+
|bsscopuu |Backward | 1-65,524 |
| |maximum SSCOP | |
| |UU size | |
+---------+---------------+---------------------------------------+
Structured Data Transfer Block Size (str): This parameter is meaningful
only when structured AAL1 is used. It indicates the size (in octets) of
the block used for structured data transfer. If not included as a local
connection option, the structure size is to be known by other means. For
instance, af-vtoa-78 [20] fixes the structure size for n x 64 service,
with or without CAS. The L: atm/str parameter is coded as the decimal
equivalent of a 16-bit field [29]. The theoretical maximum value of this
parameter is 65,535, although most services use much less.
CBR Rate (cbrRate): This is a hexadecimal representation of the bit map
defined in Table 4-6 of ITU Q.2931 [29]. This is represented as exactly
two hex digits. For example:
L: atm/cbrRate:04
implies a CBR rate of 1.544 Mbps.
Forward maximum CPCS-SDU size (fcpcs): This is the maximum size of the
AAL2 or AA5 CPCS SDU in the forward direction.
Backward maximum CPCS-SDU size (bcpcs): This is the maximum size of the
AAL2 or AA5 CPCS SDU in the backward direction.
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Forward maximum AAL2 CPCS-SDU rate (fSDUrate): This is the maximum rate of
the AAL2 CPCS-SDUs in the forward direction.
Backward maximum AAL2 CPCS-SDU rate (bSDUrate): This is the maximum rate
of the AAL2 CPCS-SDUs in the backward direction.
The fSDUrate and bSDUrate local connection options can be used to rate-
limit AAL2 CIDs, specially when used in the SSSAR [1] and frame mode [2]
contexts.
Forward maximum frame mode block size (ffrm): This is the maximum size,
in the forward direction, of the AAL2 frame mode data unit (I.366.2) [2].
Backward maximum frame mode block size (bfrm): This is the maximum size,
in the backward direction, of the AAL2 frame mode data unit (I.366.2) [2].
Forward maximum SSSAR-SDU size (fsssar): This is the maximum size, in the
forward direction, of the AAL2-based SSSAR-SDU (I.366.1) [1].
Backward maximum SSSAR-SDU size (bsssar): This is the maximum size, in
the backward direction, of the AAL2-based SSSAR-SDU (I.366.1) [1].
Forward maximum SSCOP-SDU size (fsscopsdu): This is the maximum size, in
the forward direction, of the AAL2-based SSCOP-SDU (I.366.1) [1].
Backward maximum SSCOP-SDU size (bsscopsdu): This is the maximum size, in
the backward direction, of the AAL2-based SSCOP-SDU (I.366.1) [1].
Forward maximum SSCOP-UU size (fsscopuu): This is the maximum size, in
the forward direction, of the AAL2-based SSCOP-UU field(I.366.1) [1].
Backward maximum SSCOP-UU size (bsscopuu): This is the maximum size, in
the backward direction, of the AAL2-based SSCOP- UU field (I.366.1) [1].
5.0 Signals and Events
All the events in this package are connection events. The suffix
@<connection-id> can be omitted if there is only one connection to an
endpoint. This suffix can also be wildcarded per MGCP rules.
There are no auditable event-states associated with the ATM package.
Set-up complete ( "sc"):
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Within the RequestedEvents (R: ) structure, "sc " is used to request
notification of successful ATM OR AAL2 connection set-up. The ATM OR AAL2
bearer path is ready for subscriber payload carriage when this
notification is sent.
This could be the set-up of an SVC, the assignment of an AAL2 CID path and
combinations thereof. Examples of such combinations are the set-up of an
AAL2 SVC and the assignment of a CID within it or the set-up of a
concatenation of an AAL2 single-CID SVC and a CID channel within a
multiplexed AAL2 VC.
An R: atm/sc event notification request does not automatically cause the
gateway to initiate the set-up of an ATM OR AAL2 path. The trigger for an
ATM OR AAL2 connection set-up is an "on" value of the L: atm/se local
connection option provided with a create or modify connection command.
TABLE 11: Signals and Events in the ATM package
|---------------|-----------------------|-----|------|--------------|
| SYMBOL | DEFINITION | R | S | DURATION |
|---------------|-----------------------|-----|------|--------------|
| sc | Bearer path set-up | x | | |
| | complete | | | |
|---------------|-----------------------|-----|------|--------------|
| sf | Bearer path set-up | x | | |
| | failed | | | |
|---------------|-----------------------|-----|------|--------------|
| ec | Enable CAS via | | oo | |
| | type 3 packets | | | |
|---------------|-----------------------|-----|------|--------------|
| etd | Enable DTMF tone | | oo | |
| | forwarding via | | | |
| | packets | | | |
|---------------|-----------------------|-----|------|--------------|
| etm | Enable MF tone | | oo | |
| | forwarding via | | | |
| | packets | | | |
|---------------|-----------------------|-----|------|--------------|
| etr1 | Enable MF-R1 tone | | oo | |
| | forwarding via | | | |
| | packets | | | |
|---------------|-----------------------|-----|------|--------------|
| etr2 | Enable MF-R2 tone | | oo | |
| | forwarding via | | | |
| | packets | | | |
|---------------|-----------------------|-----|------|--------------|
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|---------------|-----------------------|-----|------|--------------|
| uc (string) | Used codec changed | x | | |
| | to codec named by | | | |
| | the string | | | |
|---------------|-----------------------|-----|------|--------------|
| ptime (#) | Packetization period | x | | |
| | changed to # | | | |
|---------------|-----------------------|-----|------|--------------|
| pftrans (#) | Profile element | x | | |
| | changed to row # | | | |
|---------------|-----------------------|-----|------|--------------|
| cle (#) | Cell Loss | x | | |
| | threshold (# ) | | | |
| | exceeded | | | |
|---------------|-----------------------|-----|------|--------------|
| pl (#) | Packet Loss Threshold| x | | |
| | exceeded (# ) | | | |
|---------------|-----------------------|-----|------|--------------|
| qa | Quality Alert | x | | |
| | | | | |
|---------------|-----------------------|-----|------|--------------|
| of (#) | Operation failure: | x | | |
| | Loss of connectivity | | | |
| | with reason code # | | | |
-------------------------------------------------------------------
Set-up failed ("sf"):
Within the RequestedEvents (R: ) structure, "sf " is used to request
notification of a failed ATM OR AAL2 connection set-up. The ATM OR AAL2
connection set-ups addressed by "sf" are the same as for the "sc" event.
In some ATM OR AAL2 applications with SVC set-up or bearer-signalled AAL2
path assignment, the "sf " event might not be used. In these cases, the
following options are available:
* the call agent receives a spontaneous delete from the media gateway
with appropriate reason code (902).
* the call agent receives the "of" event described below with optional
reason code (902).
Enable CAS via type 3 packets ( "ec"):
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This signal indicates that the media gateway is to forward CAS signaling
via type 3 packets on an AAL2 connection. This does not preclude the call
agent from requesting notification of CAS state changes. On receiving this
signal request, the gateway sustains a bidirectional type 3 CAS protocol
over the AAL2 path. This comes to an end when the request is cancelled
through a subsequent NotificationRequest command or when the VoAAL2
connection is deleted.
Enable DTMF tones via type 3 packets ( "etd"):
A gateway will ignore this signal request if it normally forwards and
receives DTMF tones via type 3 packets. This signal indicates that the
media gateway is to forward and receive DTMF tones via type 3 packets on
an AAL2 connection. This does not preclude the call agent from requesting
notification of DTMF tones.
Enable MF tones via type 3 packets ( "etm"):
A gateway will ignore this signal request if it normally forwards and
receives MF tones via type 3 packets. This signal indicates that the media
gateway is to forward and receive MF tones via type 3 packets on an AAL2
connection. This does not preclude the call agent from requesting
notification of MF tones. This signal request does not specify the MF tone
type, which is known by other means.
Enable R1 MF tones via type 3 packets ( "etr1"):
A gateway will ignore this signal request if it normally forwards and
receives R1 MF tones via type 3 packets. This signal indicates that the
media gateway is to forward and receive R1 MF tones via type 3 packets on
an AAL2 connection. This does not preclude the call agent from requesting
notification of R1 MF tones.
Enable MF tones via type 3 packets ( "etr2"):
A gateway will ignore this signal request if it normally forwards and
receives R2 MF tones via type 3 packets. This signal indicates that the
media gateway is to forward and receive R2 MF tones via type 3 packets on
an AAL2 connection. This does not preclude the call agent from requesting
notification of R2 MF tones.
Used codec changed ( "uc (string) "):
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If armed via an R:atm/uc, a media gateway signals a codec change through
an O:atm/uc. The alphanumeric string in parentheses is optional. It is
the encoding name of the codec to which the switch is made. Although this
event can be used with all ATM adaptations (AAL1, AAL2 and AAL5):
* The pftrans event is more suited to AAL2 applications.
* Codec switches do not generally occur mid-call in AAL1
applications.
Packet time changed ( "ptime(#)"):
If armed via an R:atm/ptime, a media gateway signals a packetization
period change through an O:atm/ptime. The decimal number in parentheses
is optional. It is the new packetization period in milliseconds. In AAL2
applications, the pftrans event can be used to cover packetization period
changes (and codec changes).
Profile element changed ( "pftrans(#)"):
If armed via an R:atm/pftrans, a media gateway signals a mid-call profile
element change through an O:atm/ptime. This event is used with AAL2
adaptation only. A profile element is a row in a profile table. Profile
elements indicating silence should not trigger this event. The decimal
number in parentheses is optional. It is the row number to which the
switch is made. Rows are counted downward, beginning from 1.
Cell loss exceeded ( "cle(#) "):
This event indicates that the cell loss rate exceeds the threshold #. If
the threshold is omitted in the requested events and observed events
parameters, it is known by other means. The optional decimal number is the
number of dropped cells per 100,000 cells. For example, cle(10) indicates
cells are being dropped at a rate of 1 in 10,000 cells.
Packet loss exceeded ( "ple(#)"):
This event indicates that the packet loss rate exceeds the threshold #. If
the threshold is omitted in the requested events and observed events
parameters, it is known by other means. The optional decimal number is the
number of dropped packets per 100,000 packets. For example, ple(10)
indicates packets are being dropped at a rate of 1 in 10,000 packets.
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When the bearer connection uses an AAL2 CID within a multiplexed VCC
rather than an entire VCC, the 'ple' event is used instead of 'cle'. The
packets are AAL2 CPS PDUs.
Quality alert ( "qa"):
This event indicates that the bearer path fails to any predetermined
combination of quality criteria such as loss, delay, jitter etc. This
criterion is not defined and is left to the application. The gateway
reports this quality violation to the call agent if armed to do so.
Report failure ( "of (#)"):
This indicates a connection failure. It can also indicate failure to
establish a connection, in lieu of "sf".
The most common response to these events is for the media gateway to
delete the connection. Some applications might choose to report an "of"
with the appropriate reason code, a decimal number, optionally included in
parentheses. Reason codes are the same as for spontaneous deletes by the
gateway.
6.0 Statistics
The MGCP connection parameters structure is returned in an autonomous
delete connection message, and in a response to a delete or audit
connection command. The standard connections parameters [36] it contains
are redefined below for ATM. Also, a new extension parameter specific to
the ATM package is defined.
The standard connection parameters redefined for ATM are:
Number of packets sent: If a VCC is assigned to the connection, this is
the total number of ATM cells transmitted for the duration of the
connection. If a CID within an AAL2 VCC is assigned to the connection, it
is the number of AAL2 common part sublayer (CPS) packets transmitted for
the duration of the connection.
Number of octets sent: If a VCC is assigned to the connection, this is the
total number of ATM payload octets transmitted for the duration of the
connection. If a CID within an AAL2 VCC is assigned to the connection,
this is the total number of AAL2 CPS payload octets transmitted for the
duration of the connection.
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Number of packets received: If a VCC is assigned to the connection, this
is the total number of ATM cells received for the duration of the
connection. If a CID within an AAL2 VCC is assigned to the connection, it
is the number of AAL2 common part sublayer (CPS) packets received for the
duration of the connection.
Number of octets received: If a VCC is assigned to the connection, this is
the total number of ATM payload octets received for the duration of the
connection. If a CID within an AAL2 VCC is assigned to the connection,
this is the total number of AAL2 CPS payload octets received for the
duration of the connection.
Number of packets lost: If a VCC is assigned to the connection, this is
the total number of ATM cells lost, for the duration of the connection, in
the direction towards the gateway. If a CID within an AAL2 VCC is assigned
to the connection, it is the number of AAL2 common part sublayer (CPS)
packets lost, for the duration of the connection, in the direction towards
the gateway. If these losses cannot be assessed, then the gateway omits
this parameter.
Interarrival jitter: If a VCC is assigned to the connection, this is the
interarrival jitter for ATM cells. If a CID within an AAL2 VCC is assigned
to the connection, this is the interarrival jitter for AAL2 common part
sublayer (CPS) packets. If this cannot be determined, then it is
omittedor set to 0.
Average Transmission Delay: This should be understood to be the average
cell transmission delay in both cases: VCC assignment and CID assignment
to the connection. This requires the use of ATM performance monitoring
techniques. If it is not possible to assess this delay, it is omitted or
set to 0.
The following extension parameter is defined for the connection parameters
structure:
Connection qualification ("atm/CQ"): This qualifies the connection with
enough granularity to be able to use the other connection parameters
without a priori knowledge of network or connection type. Defined values
are:
1 ATM Virtual Circuit Connection (VCC)
2 AAL2 Channel Identifier (CID)
When omitted, the connection parameters must be interpreted on one of the
following bases:
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* The default interpretations for MGCP in Ref. 36.
* The call agent's prior knowledge, if it governs the type of
network and connection through the network type 'nt' LCO [Ref. 36] and/or
the connection type 'ct' LCO defined here.
* The call agent's snooping of the local connection descriptor
provided by one or more media gateway. This is used to determine the
network and connection type.
An example of connection parameter encoding for an ATM VCC is the
following:
P: PS=1245, OS=59760, PR=1244, OR=59712, PL=20, JI=0, LA=0,atm/CQ=1
Note that the PL value refers to the receive direction and is unrelated to
PS. Also, since atm/CQ=1, these parameters refer to ATM cells rather than
to AAL2 CPS packets.
As in other applications, any of these parameters can be omitted if not
relevant to an application. Also, the entire P: structure is optional.
When connection parameters are audited, all parameters normally returned
with a delete connection are returned. This includes the connection
qualification parameter, atm/CQ.
The measurement or estimation of some or all of these connection
parameters might not be feasible or beneficial in some applications. In
such cases, these may be individually omitted, or the entire connection
parameters structure, which is optional in MGCP, might be omitted.
Further, parameters which indicate impairments might be set to 0 to
nullify their impact, if any.
7.0 Negotiation of profiles and codecs in ATM applications
7.1 Consistency of parameters
For ATM networks, the "nt" local connection option in MGCP must be set to
"ATM".
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In any ATM application, the following Local Connection Options should not
be used:
Type of service, L: t
Resource reservation, L: r
This is because the Local Connection Options listed in Table 6 provide
information equivalent to the L: t and L: r local connection options.
The following Local Connection Option is not meaningful in the AAL1 case
and should not be used:
Packetization period, L: p
In AAL2 applications, the following Local Connection Options should not be
used :
Encoding algorithm, L: a
Packetization period, L: p
The following ATM Local Connection Options provide equivalent information
in the AAL2 case:
Profile list, L: atm/pfl
Priority list of voice codec selections, L: atm/vsel
Priority list of voiceband data codec selections, L: atm/dsel
Priority list of fax codec selections, L: atm/fsel
The use of a disallowed local connection option can either be flagged as
an error or ignored. If it is flagged as an error, a return code of 510
(protocol error) is used. If it is ignored, it is for the sake of
maintaining backward compatibility in some applications. A return code of
524 (inconsistent local connection options) should not be used.
7.2 Codec/Profile negotiation in ATM networks
In AAL1 and AAL5 applications, codec negotiation is similar to the IP
case, although some of the local connection options and SDP connection
descriptor parameters are different. See [18] for conventions for the use
of the Session Description Protocol [26] in the ATM context.
In AAL2 applications, the L:a and L: p parameters are disallowed. Profile
negotiation takes the place of codec negotiation. This remainder of this
section addresses how this is done.
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The specifics of the AAL2 bearer are not germane to profile negotiation.
The bearer could be PVC-based or SVC-based, based on single-CID or multi-
CID VCs, subcell multiplexed or not.
The most general case involves different prioritized lists of profiles at
the originating gateway, the terminating gateway, the originating call
agent and the terminating gateway. Whether these lists are based on
network policies, end subscriber service level agreements or equipment
design is immaterial to the profile negotiation that is done as part of
the connection establishment process. It is also irrelevant whether these
lists are hardcoded defaults or provisionable. In the connection
establishment process, a series of ordered intersections is performed.
This leaves a single ordered list in the end. The highest priority profile
in this list is the selected profile.
The call agent conveys its priority list through the pfl local connection
option. The gateway conveys intersection results through the media
information line in SDP [18]. Whether these lists imply a real priority or
not, a profile is always chosen before the profiles that follow it in a
list.
Each media gateway has a policy for assigning priorities to different
lists (inter-list priority) which is different from the positional
ordering of profiles within a list (intra-list priority). This policy
might be a hardcoded default or provisioned. The inter-list priority
specifies an ordering of the following lists with respect to each other:
* 'C-list', which is the priority list from the call agent,
received through L: atm/pfl.
* 'R-list', which is the priority list from the remote end,
received through the SDP remote connection descriptor.
* 'L-list', which is the local priority list, hardcoded or
provisioned.
Depending on the application, different inter-list priorities may be used
in the cases when the gateway originates and terminates a call.
This policy will vary depending on the type, capabilities and deployment
of the media gateway. Network administrations or equipment vendors will
provision/default this policy for various reasons such as resource usage
optimization, quality of service, likelihood of finding a common profile
etc.
When doing an ordered intersection of lists, the intra-list priorities of
the highest priority list are used. Any profile that cannot be supported
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due to resource (bandwidth, processing power etc.) limitations is
eliminated from the intersection.
In the absence of one or more of these lists, the remaining list(s) are
used in the profile selection process. If the call agent does not provide
a list of profiles, the C-list is absent. In this case, the intersection
of the C-list, R-list and L-list simply becomes the intersection of the R-
list and the L-list. If the R-list is also absent, no intersection is
performed and the result is this null operation is the L-list.
The process of profile negotiation is as shown below:
ORIGINATING TERMINATING
GATEWAY GATEWAY
(1) On receiving CRCX
do a policy-based ordered
intersection of the C-list,
and L-list. No R-list present.
---------------------------------->
(2)Send resulting ordered list
to the terminating gateway
via SDP.
(3) On receiving CRCX do
a policy-based
ordered
intersection of the
C-list, R-list and
L-list.
(4) The highest priority
profile in the
resulting
list is the
selected
profile.
<-----------------------------------
(5) Send selected profile
to the originating gateway
via SDP.
(6) Optionally, send vsel, dsel,
and fsel via SDP to map
profile rows into service
types.
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When connection establishment is complete, there is only one profile
associated with a connection. This implies that both endpoints are ready
to receive, on the fly, packets that comply with any row in the profile.
Some applications may elect to associate profile rows with one or more of
the following service types: voice service, voiceband data (modem)
service and fax service. This binding can be by default, through
provisioning or as part of profile negotiation during call establishment.
Such service type associations, when communicated to another entity, are
advisory and do not limit the requirement for supporting, at any time,
on-the-fly switches to any profile element.
Media gateways can have internal default (or provisioned) bindings between
service types and profile elements. Note that not all of these bindings
might be meaningful an in application context e.g. the fax service binding
might be omitted. As part of profile negotiation, applications might
choose to coordinate those bindings that are meaningful. When this is
done, the vsel, dsel and fsel LCOs described in this document, and the
vsel, dsel and fsel media attribute lines [18] are used to effect this
coordination. Using these constructs, entities such as call agents can
indicate preferred bindings for the first, most preferred profile in the
profile list.
When performing ordered intersections of the C-list, L-list and R-list in
the call flow above, media gateways MUST use the inter-list priority to
choose between service to profile row bindings suggested by the call
agent, the remote gateway or its own internal bindings. If the C-list has
the highest priority, and the first profile in the C-list is selected as
the first profile of the intersected list, then any service type to
profile row bindings provided by the call agent via the vsel, dsel and
fsel LCOs are associated with the first profile. If the R-list has the
highest priority, and the first profile in the R-list is selected as the
first profile of the intersected list, then any service type to profile
row bindings provided by the remote gateway via the vsel, dsel and fsel
SDP attributes [18] are associated with the first profile. If the L-list
has the highest priority, then internal (default, provisioned) service to
profile row bindings are associated with the first profile. Also, even if
the C-list or the R-list have the highest inter-list priority, the first
profile in the intersected list may not be the first profile in the
highest priority list, since the latter may be eliminated by the
intersection process. In this case, internal (default, provisioned)
service to profile row bindings are associated with the first profile.
In any of the cases above, the selected service to profile row bindings
might address some or all of the following services: voice, voiceband
data, and facsimile. At the end of profile negotiation (step 4 in the
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call flow above), there is one selected profile. Any applicable service
type to profile row bindings can are conveyed to the originating gateway
(step 6) as vsel, dsel and fsel SDP attributes [18].
An example of profile negotiation:
The L-list at gateway #1, which is the originating gateway in this
example, is:
custom 100, itu 3, itu 1, itu 8
The L-list at gateway #2, which is the terminating gateway in this
example, is:
itu 2, itu 3, itu 1, itu 5
The originating call agent sends the following profile list (C-list) to
the originating gateway in the first create connection command:
itu 8, itu 9, atmf 7, itu 3, itu 1, custom 100
Further, the originating call agent qualifies the first profile in its
list with the following service type bindings:
L: atm/vsel:G729 10 10000, atm/dsel:on PCMU 40 5000
There is no atm/fsel local connection option. Facsimile is included with
voiceband data in the atm/dsel local connection option.
There is no remote connection descriptor, hence no R-list. The policy for
originating calls at gateway #1 is:
C-List > R-list > L-list
where '>' means 'has higher priority than'. In accordance with this
policy, the originating gateway performs an ordered intersection of the C-
list and the L-list to produce:
itu 8, itu 3, itu 1, custom 100
Since the C-list has the highest priority and the first profile in the
intersected profile list is also the first profile in the C-list, the
service bindings provided by the originating call agent are associated
with the first profile, itu 8. The originating gateway sends this
result(intersected profile list and service bindings for the first
profile, itu 8) via the SDP remote sessiondescriptor to the terminating
gateway. The service bindings are expressed as follows:
a=vsel:G729 10 10000,
a=dsel:on PCMU 40 5000
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The intersected profile list produced by gateway 1 becomes the R-list for
gateway #2. The terminating call agent sends the following profile list
(C-list) to the terminating gateway in the first create connection
command:
itu 1, itu 4, itu 3, custom 110, custom 100, itu 2
Any service bindings (not shown) sent by the terminating call agent apply
to the first profile in this list, itu 1.
The policy for terminating calls at gateway #2 is:
R-list > L-list > C-list
Using this policy, gateway #2 produces the following ordered intersection
of R-list, L-list and C-list:
itu 3, itu 1
The first profile in this list, itu 3, is to be used for this connection.
Gateway 2 indicates this to the call agent through the SDP local
connection descriptor.
Note that the service bindings provided by the originating gateway have
not been specified with respect to itu 3. Therefore, these cannot be used,
even though, at the terminating gateway, the R-list has the highest
priority. The service bindings for itu 3 are the internal (default or
provisioned) service bindings at the terminating gateway. These are
indicated to the originating gateway in via the the following SDP media
attribute lines:
a=vsel:G726-32 20 5000 G726-24 15 5000
a=dsel:on PCMU 40 5000 G726-40 25 5000
These lines map voice (vsel) and voiceband data (dsel) to rows in the
profile itu 3. The "on" in the dsel line indicates that voiceband data
includes fax, otherwise a separate fsel line might have been used. Two
codecs each are indicated for voice and for voiceband data, with the first
codec being the preferred one. Although the originating gateway is not
constrained by these advisory indications of profile element to service
type mapping, applications may choose to limit on-the-fly switches based
on the current service state (voice, voiceband data etc.). If done, this
provides greater simplicity at the expense of flexibility.
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8.0 Security Considerations
The ATM package extends the base Media Gateway Control Protocol (MGCP)
[36]. This package specifies no additional security requirements or
recommendations over the those of the base MGCP protocol.
9.0 References
[1] ITU-T I.366.1, B-ISDN ATM Adaptation Layer Specification:
Type 1 AAL.
[2] ITU-T I.366.2, AAL Type 2 Reassembly Service Specific
Convergence Sublayer for Trunking, Feb. 99.
[3] af-vtoa-0113.000, ATM trunking using AAL2 for narrowband
services.
[4] ITU Q. 2965.1, Digital subscriber signalling system no.2 (DSS
2) - Support of Quality of Service classes.
[5] ITU Q.2961, Digital subscriber signalling system no.2 (DSS 2)
- additional traffic parameters. Also, Amendment 2 to Q.2961.
[6] ATMF UNI 4.0 Signaling Specification, af-sig-0061.000.
[7] ITU Q. 2965.2, Digital subscriber signalling system no.2 (DSS
2) - Signalling of individual Quality of Service parameters.
[8] ATMF Traffic Management Specification, Version 4.1, af-tm-
0121.000.
[9] I.356, BISDN ATM layer cell transfer performance.
[10] ITU-T I.363.2, B-ISDN ATM Adaptation Layer Specification: Type
2 AAL, Sept. 1997.
[11] ITU-T I.366.1, Segmentation and Reassembly Service Specific
Convergence Sublayer for AAL Type 2, June 1998.
[12] H.323-2, Packet-based multimedia communications systems.
[13] af-vtoa-0083.000, Voice and Telephony Over ATM to the Desktop.
[14] Q.2110, B-ISDN ATM adaptation layer - service specific
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connection oriented protocol (SSCOP).
[15] I.365.1,Frame relaying service specific convergence sublayer
(FR-SSCS).
[16] I.365.2, B-ISDN ATM adaptation layer sublayers: service
specific coordination function to provide the connection
oriented network service.
[17] I.365.3, B-ISDN ATM adaptation layer sublayers: service
specific coordination function to provide the
connection-oriented transport service.
[18] Conventions for the use of the Session Description Protocol
(SDP) for ATM Bearer Connections, RFC 3108, May 2001.
[19] ITU I.371, Traffic Control and Congestion Control in the BISDN.
[20] ATMF Circuit Emulation Service (CES) Interoperability
Specification, af-vtoa-0078.000.
[21] af-vmoa-0145.000, Voice and Multimedia over ATM, Loop Emulation
Service using AAL2.
[22] ITU-T H.222.1, Multimedia multiplex and synchronization for
audiovisual communication in ATM environments.
[23] FRF.5, Frame Relay/ATM PVC Network Interworking Implementation
Agreement.
[24] FRF.8, Frame Relay/ATM PVC Service Interworking Implementation
Agreement.
[25] FRF.11, Voice over Frame Relay Implementation Agreement.
[26] IETF RFC 2327, 'SDP: Session Description Protocol', April '98,
Mark Handley and Van Jacobson.
[27] ITU-T I.363.5, B-ISDN ATM Adaptation Layer Specification: Type
5 AAL, Aug. 1996.
[28] I.365.4, B-ISDN ATM adaptation layer sublayers:
Service specific convergence sublayer for HDLC applications.
[29] ITU-T Q.2931, B-ISDN Application Protocol for Access Signaling.
[30] ITU Q.765.5, Application Transport Mechanism - Bearer
Independent Call Control.
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[31] http://www.3gpp.org/ftp/Specs for specifications related to
3GPP, including AMR codecs.
[32] ITU Q.931, Digital Subscriber Signaling System No. 1: Network
Layer.
[33] ITU Q.763, SS7 - ISUP formats and codes.
[34] http://www.isi.edu/in-notes/iana/assignments/rtp-parameters.
[35] ATMF Voice and Telephony over ATM - ATM Trunking using AAL1 for
Narrowband Services, version 1.0, af-vtoa-0089.000, July 1997.
[36] Arango, M., Dugan, A., Elliott, I., Huitema, C. and S. Pickett,
"Media Gateway Control Protocol (MGCP) Version 1.0", RFC 2705,
October 1999.
[37] Handley, M. and V. Jacobson, "SDP: Session Description Protocol",
RFC 2327, April 1998.
[38] Foster, B., ôMGCP CAS Packagesö, RFC 3064, February 2001.
10.0 Acronyms
AAL ATM Adaptation Layer
ABR Available Bit Rate
ABT/DT ATM Block Transfer/Delayed Transmission
ABT/IT ATM Block Transfer/Immediate Transmission
ATM Asynchronous Transfer Mode
ATMF ATM Forum
BCG Bearer Connection Group
CAS Channel Associated Signaling
CBR Constant Bit Rate
CDV Cell Delay Variation
CDVT Cell Delay Variation Tolerance
CID Channel Identifier
CLR Cell Loss Ratio
CPS Common Part Sublayer
DBR Deterministic Bit Rate
FEC Forward Error Correction
FRF Frame Relay Format
GFR Guaranteed Frame Rate
GWID Gateway Identifier
IP Internet Protocol
ITU International Telecommunications Union
LCO Local Connection Option
MBS Maximum Burst Size
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MCR Minimum Cell Rate
MFS Maximum Frame Size
MGCP Media Gateway Control Protocol
nrt-VBR Non-real-time Variable Bit Rate
NSAP Network Service Access Point
PCR Peak Cell Rate
PDU Protocol Data Unit
PVC Permanent Virtual Circuit
QoS Quality of Service
rt-VBR Real-time Variable Bit Rate
SAR Segmentation and Re-assembly
SCR Sustained Cell Rate
SDT Structured Data Transfer
SDU Service Data Unit
SPVC Switched Permanent Virtual Circuit
SRTS Synchronous Residual Time-Stamp
SSCOP Service-specific Connection Oriented Protocol
SSSAR Service-specific Segmentation and Re-assembly
SVC Switched Virtual Circuit
TDM Time-Division Multiplexing
UBR Unspecified Bit Rate
UDT Unstructured Data Transfer
VC Virtual Circuit
VCCI Virtual Circuit Connection Identifier
VCI Virtual Circuit Identifier
VP Virtual Path
VPCI Virtual Path Connection Identifier
VPI Virtual Path Identifier
11.0 Acknowledgements
The author wishes to thank several colleagues at Cisco and the industry
who have contributed towards the development of the MGCP ATM package, and
who have implemented and tested these constructs. Special thanks are due
to Bill Foster, Flemming Andreasen, Raghu Thirumalai Rajan, Joe Stone,
Hisham Abdelhamid,Joseph Swaminathan, David Auerbach and Robert Biskner
of Cisco systems and to Mahamood Hussain of Hughes Software Systems for
their contributions.
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12.0 Author's Address
Rajesh Kumar
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
Phone: 1-800-250-4800
Email: rkumar@cisco.com
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