Internet Engineering Task Force R. Kumar Internet Draft Cisco Systems Document: <draft-rajeshkumar-mgcp-atm-package-00.txt> November 2000 Category: Informational ATM MGCP Package 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. Internet-Drafts are draft documents valid for a maximum of six months and 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 This document describes an ATM MGCP package which includes new Local Connection Options, ATM specific events and signals and ATM statistics parameters. Also included in a description of profile negotiation. 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. 3.0. ATM Package The ATM package in this document consists of Local Connection Options which are described in section 3.1, Events and Signals - section 3.2 and ATM statistics parameters - section 3.3. Also included in the document is a section on what Local Connection Options should not be included to insure consistency with the ATM parameters - section 4.1, and a section on profile negotiation - section 4.2. R.Kumar Informational 1 ATM MGCP Package October 2000 3.1. ATM Local Connection Options For ATM networks, the "nt" local connection option in MGCP must be set to "ATM". Some additional Local Connection Option (LCO) parameters are also required. Besides being included in the LCO used in the create connection, modify connection and audit connection transactions, these parameters are included in the capabilities structure in audit endpoint transactions. In the ATM networks addressed here, services are carried directly over ATM without an intervening IP layer. The LCO 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 LCO parameters defined for IP are sufficient. ATM Local Connection Options are divided into the following categories: basic, bearer assignment, AAL1, AAL2, AAL5 and traffic management. Note that the local connection option names described are used without the ("atm") package prefix. 3.1.1 Basic ATM local connection options Basic local connection options are common to a wide range of applications. These are listed in the following table and then explained in detail. +---------+---------------+---------------------------------------+ | ATM LCO | Meaning | Values | +---------+---------------+---------------------------------------+ | ct | Connection |AAL1, AAL1_SDT, AAL1_UDT, AAL2, AAL3/4,| | | Type |AAL5, USER_DEFINED_AAL | +---------+---------------+---------------------------------------+ | aalApp | Application |itu_h323c,af83,assuredSSCOP, | | | |nonassuredSSCOP, itu_i3661, itu_i3662, | | | |itu_i3651,itu_i3652, itu_i3653, | | | |FRF5, FRF8, FRF11,itu_h2221 | +---------+---------------+---------------------------------------+ | sbc | Subchannel | 1...24 for T1-based applications | | | Count | 1...31 for E1-based applications | +---------+---------------+---------------------------------------+ | vc |VC/Bearer type | PVC, SVC, CID | +---------+---------------+---------------------------------------+ | pf | Partial fill | 1...48 | | | | | +---------+---------------+---------------------------------------+ | vsel | Voice codec | See below | | | Selection | | +---------+---------------+---------------------------------------+ | dsel | Data codec | See below | | | Selection | | +---------+---------------+---------------------------------------+ R.Kumar Informational 2 ATM MGCP Package October 2000 +---------+---------------+---------------------------------------+ | fsel | Fax codec | See below | | | Selection | | +---------+---------------+---------------------------------------+ | 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 | | +---------+---------------+---------------------------------------+ 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. AAL application (aalApp): This specifies the application layer on top of the adaptation layer. The following is a non-exhaustive list of strings describing certain applications. Other strings are possible. If used, these need to be defined a priori for an application. "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]. "assuredSSCOP" SSCOP as defined in ITU Q.2110 [14]. assured operation. "nonassuredSSCOP" SSCOP as defined in ITU Q.2110 [14], non-assured operation. "itu_i3661" SSCS per ITU I.366.1 [11]. "itu_i3662" SSCS per ITU I.366.2 [2]. "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]. "itu_i3653" Service-specific coordination function, as defined in ITU I.365.3, for Connection Oriented Transport Service (SSCF-COTS) [17]. "FRF5" Use of the FRF.5 frame relay standard [23]. R.Kumar Informational 3 ATM MGCP Package October 2000 "FRF8" Use of the FRF.8 frame relay standard [24]. "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. 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 "SVC" does not imply that the gateway will or should set up an SVC. Rather, an L:se:on parameter (described below) is used to explicitly request an SVC set-up. 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. R.Kumar Informational 4 ATM MGCP Package October 2000 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 multiple of the structure size (e.g. a partial fill size of 40 is truncated to 36 to support six 6 x 64 channels). 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. 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 ms. 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). 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 ms. 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: R.Kumar Informational 5 ATM MGCP Package October 2000 <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 ms. 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: vsel:G729 10 10 G726-32 40 10 L: dsel:off PCMA 10 10 G726-32 40 10 L: fsel:PCMU 40 5 G726-32 20 5 L: vsel:G729 10 10 G726-32 40 10 L: dsel:on PCMA 10 10 G726-32 40 10 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: vsel:G729 - - G726-32 - - L: dsel:- G729 - - G726-32 - - L: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 determine the 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 below), the profile qualified by these local connection options is the first profile in the list. Forward maximum CPCS-SDU size (fcpcs): Here, forward is the direction away from the media gateway. The format of this parameter is described below. Backward maximum CPCS-SDU size (bcpcs): Here, backward is the direction towards the media gateway. The format of this parameter is described below. The range of values for fcpcs and bcpcs depends on the adaptation as follows: R.Kumar Informational 6 ATM MGCP Package October 2000 |--------------|-----------------------| | Adaptation | Range | |--------------|-----------------------| | AAL5 | 1 - 65,535 | |--------------|-----------------------| | AAL2 | 45 or 64 | |--------------|-----------------------| 3.1.2 ATM Bearer Assignment local connection options These are listed in the following table and then explained in detail. +---------+---------------+---------------------------------------+ | ATM LCO | Meaning | Values | +---------+---------------+---------------------------------------+ | se | Enable path | on, off | | | set-up | | +---------+---------------+---------------------------------------+ | ci | Connection | See below | | | Element | | | | Identifier | | +---------+---------------+---------------------------------------+ 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 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 option allows the flexible support of both the backwards and forward SVC set-up methods. In the former case, the call-terminating gateway sets up the SVC. In the latter case, the call-originating gateway sets up the SVC. 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. It can be expressed with implicit or explicit designation of subparameter types. With explicit designation, subparameters are identified by constant strings followed by a hyphen and the actual subparameter. With implicit designation, the constant strings are omitted. With explicit subparameter type designation, the ci parameter can be in one of the following formats: * VCCI-<vcci> * VCCI-<vcci>/CID-<cid> * <ATMaddressType>-<ATMaddress>/VCCI-<vcci> * <ATMaddress>/VCCI-<vcci> R.Kumar Informational 7 ATM MGCP Package October 2000 * <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> With implicit subparameter type designation, the ci parameter can be in one of the following formats: * <vcci> * <vcci>/<cid> * <ATMaddressType>-<ATMaddress>/<vcci> * <ATMaddress>/<vcci> * <ATMaddressType>-<ATMaddress>/<vcci>/<cid> * <ATMaddress>/<vcci>/<cid> * <bcg>/<vcci> * <bcg>/<vcci>/<cid> * <bcg>/<vpi>/<vci> * <bcg>/<vpi>/<vci>/<cid> * <portId>/<vpi>/<vci> * <portId>/<vpi>/<vci>/<cid> * <vpci>/<vci> * <vpci>/<vci>/<cid> * <ATMaddressType>-<ATMaddress>/<vpci>/<vci> * <ATMaddress>/<vpci>/<vci> * <ATMaddressType>-<ATMaddress>/<vpci>/<vci>/<cid> * <ATMaddress>/<vpci>/<vci>/<cid> The subparameters of the ci parameter are defined as follows: |--------------|-----------------------|----------------------------| | Subparameter | Meaning | Representation | |--------------|-----------------------|----------------------------| | vcci | VC connection Id | 16-bit equivalent | |--------------|-----------------------|----------------------------| | cid | Channel Id | 8-bit equivalent | |--------------|-----------------------|----------------------------| |ATMaddressType| ATM address type | "NSAP", "E164", "GWID", | | | | "ALIAS" |--------------|-----------------------|----------------------------| R.Kumar Informational 8 ATM MGCP Package October 2000 |--------------|-----------------------|----------------------------| | ATMaddress | ATM address | 40 hex digits ("NSAP") | | | | upto 15 digits ("EI64") | | | | upto 32 chars ("GWID") | | | | upto 32 chars ("ALIAS") | |--------------|-----------------------|----------------------------| | bcg |Bearer Connection Group| 8-bit equivalent | |--------------|-----------------------|----------------------------| | vpi | Virtual Path Id | 8 or 12-bit equivalent | |--------------|-----------------------|----------------------------| | vci | Virtual Channel Id | 16-bit equivalent | |--------------|-----------------------|----------------------------| | portID | Port Id | Upto 32 digits (decimal or | | | | hex) or up to 32 characters| |--------------|-----------------------|----------------------------| | vpci | VP connection ID | 16-bit equivalent | | | | | |--------------|-----------------------|----------------------------| 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. 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. Since <vpci> and <vcci> values are unique between a pair of nodes, 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 or in a subnet. In this case, the ATM address of the far end is not needed to qualify theseparameters. The <portId> parameter is used to identify the physical trunk port on a stand-alone ATM node or on a multiplexer into which the gateway is plugged as a tributary module. It can be represented as a decimal or hex number of up to 32 digits, or an alphanumeric string of up to 32 characters. 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 "$" wildcard character can be substituted for some of the terms of this parameter. A wildcarded ci parameter can use the explicit or implicit formats described above. In the former, the constant strings that qualify the terms in the ci parameter are retained. The concatenation <ATMaddressType>-<ATMaddress> can be wildcarded in the following ways: R.Kumar Informational 9 ATM MGCP Package October 2000 * The entire concatenation, <ATMaddressType>-<ATMaddress>, is replaced with a "$". * <ATMaddress> is replaced with a "$", but <ATMaddressType> is not. Examples of wildcarding the ci parameter in the AAL1 and AAL5contexts are: $, 62/$, 100/20/$, VCCI-$, BCG-100/VPI-20/VCI-$. Examples of wildcarding the <virtualConnectionId> in the AAL2 context are: $, 62/$, 100/20/$, VCCI-40/CID-$, BCG-100/VPI-20/VCI-120/CID-$. If the ATMaddressType is NSAP, the ATMaddress is expressed as a string of 40 hex characters. As an option, dots can be included after 16-bit fields, with the first dot following an 8-bit field (standard dotted hex NSAP format). The last octet of the NSAP address is the 'selector' field that is not used for ATM addressing and is available for non-standard use. For example: L: 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: 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 meaning that the address is a Gateway Identifier or Node Alias. This may or may not be globally unique. In this case, the ATMaddress is expressed as alphanumeric string ("A"-"Z", "a"-"z", "0" - "9",".","-","_"). For example: L: ci:GWID officeABCmgx101vism12 The keyword "ALIAS" can be substituted for "GWID". For example: L: 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. Some network administrations might restrict it to a smaller size (e.g. 15 characters). 3.1.3 AAL1 local connection options These are useful in AAL1 applications. All AAL1 applications do not use all these options. These options are first listed and then explained in detail. R.Kumar Informational 10 ATM MGCP Package October 2000 +---------+---------------+---------------------------------------+ | ATM LCO | Meaning | Values | +---------+---------------+---------------------------------------+ | crt | Clock Recovery| NULL, SRTS, ADAPTIVE | | | Type | | +---------+---------------+---------------------------------------+ | str | Structure | 1...65,535 | | | Size | | +---------+---------------+---------------------------------------+ | fe | FEC enable | NULL, DELAY_SENSITIVE,LOSS_SENSITIVE | +---------+---------------+---------------------------------------+ Clock recovery type (crt): This is used in AAL1 UDT (unstructured data transfer) applications only. It takes on 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 is "NULL". Structured Data Transfer Block Size (str): This parameter is meaningful only when structured AAL1 is used (L: ct:AAL1_SDT). 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:str parameter is coded as a 16-bit field along the lines of ITU Q.2931. The theoretical maximum value of this parameter is is 65,535, although most services use much less. 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 this capability and indicates that FEC is not enabled for an AAL1 connection. 3.1.4 AAL2 local connection options These are useful in AAL2 applications. All AAL2 applications do not use all these options. These options are first listed and then explained in detail. R.Kumar Informational 11 ATM MGCP Package October 2000 +---------+---------------+---------------------------------------+ | ATM LCO | Meaning | Values | +---------+---------------+---------------------------------------+ | pfl | Profile List | See below | | | Type | | +---------+---------------+---------------------------------------+ | mxcd | Maximum number| 1...255 | | | of CIDs | | +---------+---------------+---------------------------------------+ | tmcu | Combined use | Integer microseconds | | | timer | | +---------+---------------+---------------------------------------+ | frmd | Frame mode | on,off | | | enable | | +---------+---------------+---------------------------------------+ | genpcm | Generic PCM | PCMA, PCMU | | | setting | | +---------+---------------+---------------------------------------+ | adt | Assured data | on, off | | | transfer | | +---------+---------------+---------------------------------------+ | ted | Transmission | on, off | | |error detection| | +---------+---------------+---------------------------------------+ | aalsap |Service access | AUDIO, MULTIRATE | | |point | | +---------+---------------+---------------------------------------+ | ffrm |Forward maximum| 1-65,535 | | |frame block | | | |size | | +---------+---------------+---------------------------------------+ | bfrm |Backward | 1-65,535 | | |maximum frame | | | |block size | | +---------+---------------+---------------------------------------+ 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. R.Kumar Informational 12 ATM MGCP Package October 2000 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, 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. For example, "IEEE:00000C" is one of the <oui> values that refers 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: pfl:AAL2/ITU 8 AAL2/ATMF 7 AAL2/custom 100 AAL2/cisco 200, AAL2/IEEE:00000C 150 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 = 6 HEXDIG;exactly 6 hex digits per IEEE Standard 802-1990 space = %d32 Maximum number of multiplexed CIDs (mxcd): This can take on values in the range 1...255. It is represented in decimal or hex (0x prefix) format. R.Kumar Informational 13 ATM MGCP Package October 2000 AAL2 combined use timer (tmcu): This is defined in ITU I.363.2 [10]. It is represented as an integer number of microseconds. AAL2 frame mode data enabled (frmd): Frame mode data is defined in ITU I.366.2 [2]. The frmd local connection option can take on the following values: on, off. Generic PCM setting (genpcm): This indicates whether generic PCM encoding in AAL2 profiles is A-law or Mu-law. It takes on string values of "PCMA" and "PCMU". Assured data transfer (adt): Assured data transfer is defined in ITU I.366.1 [11]. The adt local connection option can take on the following values: on, off. 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. 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. Forward maximum frame mode block size (ffrm) and backward maximum frame mode block size (bfrm): This is the maximum size of the frame mode data unit (I.366.2) [2] or the SSSAR-SDU (I.366.1)[11]. Here, forward refers to the direction away from the media gateway. Backward refers to the direction towards the media gateway. The range of values is 1 - 65,535. 3.1.5 AAL5 local connection options In the future, local connection options specific to AAL5 might be defined. Currently, there are none. AAL5 applications are adequately addressed by other local connection options. 3.1.6 ATM Traffic Management local connection options These are listed in the following table and then explained in detail. R.Kumar Informational 14 ATM MGCP Package October 2000 +---------+---------------+---------------------------------------+ | ATM LCO | Meaning | Values | +---------+---------------+---------------------------------------+ | atc | ATM transfer |CBR, nrt-VBR, rt-VBR, UBR, ABR, GFR, | | | capability or |DBR,SBR,ABT/IT,ABT/DT,ABR | | | service | | | | category | | +---------+---------------+---------------------------------------+ | subtype |atc subtype | 1...3 | +---------+---------------+---------------------------------------+ | qos | QoS class | 0...5 | +---------+---------------+---------------------------------------+ | bcob |Broadband | 0...31 | | |Connection | | | |-Oriented | | | |Bearer Class | | +---------+---------------+---------------------------------------+ | stc |Susceptibility |0...3 | | |to clipping | | +---------+---------------+---------------------------------------+ | upcc |User plane |0...3 | | |connection | | | |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, | | | |backward | | | |direction, | | | |CLP=0 | | +---------+---------------+---------------------------------------+ | adb0+1 |ATM traffic | List, see below | | |descriptor, | | | |forward | | | |direction, | | | |CLP-independent| | +---------+---------------+---------------------------------------+ R.Kumar Informational 15 ATM MGCP Package October 2000 +---------+---------------+---------------------------------------+ | adb |ATM traffic | List, see below | | |descriptor, | | | |backward | | | |direction, | | | |CLP=0 | | +---------+---------------+---------------------------------------+ | abrf |ABR parameters,| List, see below | | |forward | | | |direction | | +---------+---------------+---------------------------------------+ | abrb |ABR parameters,| List, see below | | |backward | | | |direction | | +---------+---------------+---------------------------------------+ ATM transfer capability (atc): This parameter indicates the 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. atc Subtype (subtype): This qualifies the atc local connection option. It can be assigned integer values of 1...3. Combining the atc and the subtype parameters yields the following ATM transfer capabilities and service categories defined in [19] and [8]: UBR.1, UBR.2, GFR.1, GFR.2, SBR.1, SBR.2, SBR.3, nrt-VBR.1, nrt-VBR.2, nrt-VBR.3, rt-VBR.1, rt- VBR.2, rt-VBR.3. 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. Their hex equivalents, 0x0 - 0x5 shall also be accepted. These values are mapped into QoS clases 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 R.Kumar Informational 16 ATM MGCP Package October 2000 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). All values except those listed below are reserved. ---------------------------------------------------------- | VALUE | MEANING | ---------------------------------------------------------- | 1 | BCOB-A | ---------------------------------------------------------- | 3 | BCOB-C | ---------------------------------------------------------- | 16 | BCOB-X | ---------------------------------------------------------- | 24 | BCOB-VP (transparent VP service) | ---------------------------------------------------------- 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><actd><cctd><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. R.Kumar Informational 17 ATM MGCP Package October 2000 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]. The CTD parameters, <actd> and <cctd>, refer to the acceptable and cumulative CTDs respectively in milliseconds. These are represented as the decimal or hex equivalent of 16-bit fields. These parameters are equivalent to the maximum end-to-end transit delay defined in ATMF TM 4.1 specification [8] and Q.2965.2 [7]. 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: aqf:PP 8125 3455 32000 - 11 L: 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 acceptable maximum cell transfer delay of 32 ms, a backward acceptable maximum cell transfer delay of 18 ms, an unspecified forward cumulative cell transfer delay, an unspecified backward cumulative cell transfer 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 parameters have the following format: <pcr><scr><mbs><cdvt><mcr><mfs><fd><te> These parameters are defined in the ATMF TM 4.1 specification [8]. These definitions are reiterated briefly in the table below. R.Kumar Informational 18 ATM MGCP Package October 2000 Each of these parameters can be set to "-" if the intent is to not specify it via MGCP. The meaning and units of these parameters are as follows: 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 Examples of these local connection options are: L: adf0+1: 200 100 20 - - - on -, adf0: 200 100 20 - - - on -, adb0+1: 200 100 20 - - - on -, adb0: 0 200 80 15 - - - - off This example applies to an rt-VBR, single-CID AAL2 voice VC. It 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 parameters have the following format: <nrm><trm><cdf><adtf> R.Kumar Informational 19 ATM MGCP Package October 2000 These are defined in [6] and [8]. Their definition is summarized in the table below. In MGCP, these are represented as the decimal equivalent of the binary fields mentioned below. +-----------+---------------------------------+-----------------------+ | 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 | | +-----------+---------------------------------+-----------------------+ 3.2. 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. Package Name: ATM ---------------|-----------------------|-----|------|-------------- | 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 | | | | |---------------|-----------------------|-----|------|--------------| R.Kumar Informational 20 ATM MGCP Package October 2000 |---------------|-----------------------|-----|------|--------------| | 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 (# ) | | | | |---------------|-----------------------|-----|------|--------------| | of (#) | Operation failure: | x | | | | | Loss of connectivity | | | | | | with reason code # | | | | ------------------------------------------------------------------- Set-up complete ( "sc"): 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:se local connection option provided with a create or modify connection command. 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). R.Kumar Informational 21 ATM MGCP Package October 2000 * the call agent receives the "of" event described below with optional reason code (902). Enable CAS via type 3 packets ( "ec"): 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) "): If armed via an R:uc, a media gateway signals a codec change through an O:uc. The alphanumeric string in parentheses is optional. It is the encoding name of the codec to which the switch R.Kumar Informational 22 ATM MGCP Package October 2000 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:ptime, a media gateway signals a packetization period change through an O: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: pftrans, a media gateway signals a mid-call profile element change through an O: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. 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. R.Kumar Informational 23 ATM MGCP Package October 2000 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. 3.3. Statistics Connection statistics reported in the MGCP connection parameters structure as a result of a delete connection command are redefined for ATM. These parameters 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. 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 R.Kumar Informational 24 ATM MGCP Package October 2000 common part sublayer (CPS) packets. If this cannot be determined, then it is omitted. 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. An example of connection parameter encoding for Voice-over-ATM is the following: P: PS=1245, OS=59760, PR=1244, OR=59712, PL=20, JI=0, LA=0 Note that the PL value refers to the receive direction and is unrelated to PS. As in other applications, any of these parameters can be omitted if not relevant to an application. Also, the entire P: structure is optional. If a VCC is assigned to an MGCP-controlled connection, PS, PR and PL refer to cells sent, received and lost rather than to packets. OS and OR refer to sent and received ATM payload octets. Interarrival jitter (JI) is understood to be for cells within the VCC. This VCC could be AAL1, AAL2 single-CID or AAL5. If a CID within an AAL2 VCC is assigned to an MGCP-controlled connection, PS, PR and PL refer to AAL2 common part sublayer (CPS) packets. OS and OR refer to sent and received AAL2 payload octets. Interarrival jitter (JI) is understood to be for CPS packets. If this cannot be determined, the interarrival jitter for cells can be substituted. Estimation of average transmission delay (LA) is difficult in an ATM network and requires elaborate performance monitoring techniques. Methods for measuring latency at the CID level are not standardized. If the latency parameter or any other parameter cannot be determined, it is set to a null value. Zero values shall be recognized as null values for all parameters in the Connection Parameters structure for ATM. 4.0. Negotiation of profiles and codecs in ATM applications 4.1. Consistency of parameters In any ATM application, the following Local Connection Options should not be used: Type of service, L:t Resource reservation, L:r The following ATM Local Connection Options provide equivalent information: R.Kumar Informational 25 ATM MGCP Package October 2000 ATM traffic descriptors, L:adf0+1, adb0+1, adf0, adb0 ATM transfer capability, L:atc QoS class, L:qos Broadband Connection-Oriented Bearer Class, L:bcob Susceptibility to clipping, L:stc ATM QoS parameters, L:aqf, aqb ABR parameters, L:abrf, abrb 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:pfl Priority list of voice codec selections, L: vsel Priority list of voiceband data codec selections, L: dsel Priority list of fax codec selections, L: 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. 4.2. 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. 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 R.Kumar Informational 26 ATM MGCP Package October 2000 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 it 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 when the gateway originates a call, and another ordering when the gateway terminates a call: * 'C-list', which is the priority list from the call agent, received through L: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. 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 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. R.Kumar Informational 27 ATM MGCP Package October 2000 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, R-list and L-list. ----------------------------------> (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. 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. This can be restricted in some applications to map profile rows into 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. One way of mapping profile rows to service types (voice, voiceband data and facsimile) on a call-by-call basis is to let the terminating gateway make this decision. In step 6 of the call flow above, it indicates it to the originating gateway via SDP vsel, dsel and fsel media attribute lines [18]. Another way is to let the call agent(s) determine it and communicate it to the gateways as vsel, dsel and fsel LCOs. In addition, call agents and the originating gateway can indicate their preferred mapping of profile rows to service types with R.Kumar Informational 28 ATM MGCP Package October 2000 respect to the highest priority profile listed. This is done through the vsel, dsel and fsel LCOs and media attribute lines. When one profile is selected, the originating gateway is obliged to honor any mapping of profile rows to service types provided by the terminating gateway. Additionally, such a mapping can be suggested by call agents and media gateways prior to this step (i.e. prior to step 6 in the call flow above), but the recipients are not obliged to honor these suggestions. Examples of profile negotiation: The L-list at gateway #1, which is the originating gateway in this example, is: custom 100, itu 7, itu 1, itu 2 The L-list at gateway #2, which is the terminating gateway in this example, is: itu 2, itu 7, 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 7, itu 1, custom 100 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 7, itu 1, custom 100 It sends this result via the SDP remote session descriptor. This 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 7, custom 110, custom 100, itu 2 The policy for 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 7, itu 1 The first profile in this list, itu 7, is to be used for this connection. Gateway 2 indicates this to the call agent through the SDP local connection descriptor. Along with it, is sends the following SDP media attribute lines to indicate the use of the different profile rows [18]: a=vsel:G729 10 10 a=dsel:on PCMU 40 5 R.Kumar Informational 29 ATM MGCP Package October 2000 These lines map voice (vsel) and voiceband data (dsel) to rows in the profile itu 7. The "on" in the dsel line indicates that voiceband data includes fax, otherwise a separate fsel line would be used. If the call agent(s) make(s) this decision, then the originating call agent can send the following LCOs in the modify connection command that has the selected profile in its remote connection descriptor: L: vsel:G729 10 10, dsel: G729 10 10, fsel:G729 10 10 In this case, the terminating call agent can send the vsel, dsel and fsel options in another modify connection command to the terminating gateway. 5.0. 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 connection oriented protocol (SSCOP). R.Kumar Informational 30 ATM MGCP Package October 2000 [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, draft-ietf-mmusic-sdp-atm- 02.txt. [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. 6.0. 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, Mohamed Mostafa, David Auerbach and Robert Biskner of Cisco systems for their contribution. R.Kumar Informational 31 ATM MGCP Package October 2000 7.0. Author's Address Rajesh Kumar Cisco Systems, Inc. M/S SJC01/3 170 West Tasman Drive San Jose, CA 95134-1706 Phone: 1-800-250-4800 Email: rkumar@cisco.com Full Copyright Statement Copyright (C) The Internet Society (March 2, 2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." R.Kumar Informational 32
Datatracker
draft-rajeshkumar-mgcp-atm-package-00
Internet-Draft
