A.6 Terminations

29.3323GPPMedia Gateway Control Function (MGCF) - IM Media GatewayMn interfaceRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

A.6.1 Termination Names

A.6.1.1 General

The Termination ID structure is provisioned in the MGC and MG and is known by the MG and the MGC at or before start up.

With ephemeral ATM/AAL2 and IP endpoint bearer types the internal structure of Termination ID is irrelevant for MGW and MGC and therefore Termination ID is only a numeric identifier for the termination. When bearer type is a physical timeslot within TDM circuit the Termination ID structure shall follow the Termination naming convention for TDM circuit bearer.

Ephemeral terminations are further denoted in the profile by the following:

– BICC (meaning applies to terminations towards BICC)

– BICC ATM (meaning applies to terminations towards BICC with ATM transport)

– BICC IP (meaning applies to terminations towards BICC with IP transport)

– IMS (meaning applies to terminations toward IMS)

– Multiplex (meaning applies to terminations performing multiplexing)

– RTP-CN (meaning applies to terminations towards SIP-I on Nc)

A.6.1.2 ASN.1 Encoding

A.6.1.2.1 General Structure

The following general structure of TerminationID shall be used:

4 octets shall be used for the termination ID. The following defines the general structure for the termination ID:

Termination type

Termination type:

Length 3 bits

Values:

000 Reserved

001 Ephemeral termination

010 TDM termination

011 – 110 Reserved

111 Reserved for ROOT termination Id (ROOT Termination Id = 0xFFFFFFFF)

Length 29 bits.

Usage dependent on Termination type. TDM terminations specified below in subclause 5.2.2. Other usage un-specified.

The use of wildcarding for the Termination Id shall be performed using 1 octet only.

A.6.1.2.2 Termination naming convention for TDM terminations

Table C.6.1.2.2/1 ASN.1 coding

Termination type (=010 )

PCM system

Individual

PCM system:

Length 24 bits

Usage unspecified. Uniquely identifies PCM interface in MGW

Individual:

Length: 5 bits

Max. of 32 individuals (timeslots) per PCM system (max. 24 for a 24 channel system)

A.6.1.3 ABNF coding:

A.6.1.3.1 General Structure

The following general structure of termination ID shall be used:

TerminationID = "ROOT" / pathName / "$" / "*" ; according to ITU-T H.248.1 [9] Annex B.

A.6.1.3.2 Termination Naming Convention for TDM Terminations

A.6.1.3.1.1 Naming Structure

A hierarchical naming structure is recommended for physical Terminations.

The PCMsystem is recommended to follow the following physical and digital signal hierarchy:

PCMsytem = <unit-type1>_<unit #>/<unit-type2>_<unit #>/…

The <unit-type> identifies the particular hierarchy level.

Some example values of <unit-type> are:

"s", "su", "stm4", "stm1", "oc3", "ds3", "e3", "ds2", "e2", "ds1", "e1" where "s" indicates a slot number and "su" indicates a sub-unit within a slot.

Leading zeroes MUST NOT be used in any of the numbers ("#") above.

The <unit #> is a decimal number which is used to reference a particular instance of a <unit-type> at that level of the hierarchy. Value ranges always starting with one.

The number of levels and naming of those levels is based on the physical hierarchy within the Media Gateway.

Here are some examples of the Termination structure:

1. TDM Terminations at SDH STM-1 ports:
tdm/s_<Card ID>/stm1_<STM1 ID>/e1_<E1 ID>/<channel #>

e.g., tdm/s_2/stm1_3/e1_17/25

2. TDM Terminations at PDH E1 ports (e.g., for "PCM system" only applications):
tdm/s_<Card ID>/e1_<E1 ID>/<channel #>

e.g., tdm/s_2/e1_17/25

NOTE 1: This Termination naming convention may be used to align with ASN.1 TDM Termination names as defined in A.6.1.2.2. The alignment must take into account the numbering scheme of "<E1 ID>" with the"PCM system" field, and the upper level(s) are regarded as prefix ("tdm/s-<Card ID>" versus "3-bit codepoint for ‘TDM’ ").

NOTE 2: See also clause 3/H.248.33 concerning "PCM system" definition.

3. TDM Terminations at SONET OC-3 ports:
tdm/s_<Card ID>/oc3_<OC3 ID>/ds1_<DS1 ID>/<channel #>

e.g., tdm/s_2/oc3_3/ds1_17/22

A.6.1.3.1.2 Syntactical Specification

The syntax specification may be used for the population of valid TDM TerminationID structures for.

ABNF (IETF RFC 4234) is used for the syntax specification.

pathName = TDMToken SLASH (PCMsystem / "*")

TDMToken = "tdm"

PCMsystem = 0*(HierarchyLevelHIGHToken SLASH) HierarchyLevelLOWToken

HierarchyLevelHIGHToken = (UnitTypeToken "_" UnitNumber)

HierarchyLevelLOWToken = (UnitTypeToken "_" Wildcard) / Channel / Wildcard

UnitTypeToken = "ChassisToken" / "SDHToken" / "SONETToken" / "PDHToken"

ChassisToken = "s" / "su" ; slot, sub-unit within slot

SDHToken = "stm4" / "stm1" ; relevant is capacity, but not
electrical or optical interface type

SONETToken = "oc12" / "oc3"

PDHToken = "ds3" / "e3" / "ds2" / "e2" /"ds1" / "e1" ; ANSI & ETSI

UnitNumber = 1*DIGIT

Channel = %d0-31 / %d0-23 ; value range E1/T1 system

Wildcard = "*"

A.6.1.3.1.3 Wildcarding

Wildcarding (CHOOSE, ALL) is allowed for number fields ("<unit #>").

Examples for wildcarding:

1. TDM Terminations at SDH STM-1 ports:

e.g., wildcarding on top level: tdm/*

e.g., wildcarding on slot level: tdm/s_3/*

e.g., wildcarding on STM-1 level: tdm/s_3/stm1_4/*

e.g., wildcarding on E1 level: tdm/s_2/stm1_4/e1_49/*

2. TDM Terminations at PDH E1 ports:

e.g., wildcarding on E1 level: tdm/s_1/e1_2/*

A.6.1.3.1.4 Heterogeneous TDM Port Configurations

An homogeneous TDM port configuration relates to a MGW with a single port type for physical Terminations. There is therefore a single TDM Termination name structure in use.

Heterogeneous TDM configurations means different port types, either by different signal hierarchies, like SDH/STM-1 and SDH/STM-4, and/or a mix of SDH and PDH interfaces. The number of port types in use is determining the number of TDM Termination name structures. With heterogeneous configurations the TDM Termination name structure may be aligned, for instance, by using the "highest common digital signal hierarchy" as highest Termination name hierarchical level. There is consequently a single TDM Termination name structure with a "flattened" hierarchy.

Example:

MGW with SDH/STM-1 and PDH/E1 ports. Common denominator is "e1", a selected TDM Termination name might be therefore a common two-level structure with "tdm/e1_<E1 ID>/<channel #>". The unit types "s", "su" or "stm1" are not used here.

NOTE: This concept is followed in A.6.1.2.2, ASN.1 for TDM Terminations.

A.6.1.3.2 Termination Naming Convention for Ephemeral Terminations

A.6.1.3.2.1 Naming Structure

An alphanumeric pathname structure is recommended for Ephemeral terminations:

ephemeral/<string of alphanumeric characters or "/">

e.g., Ephemeral/1/0/40000

A.6.1.3.2.2 Syntactical Specification

The syntax rules may be used for the population of valid ephemeral TerminationID structures for.

ABNF (IETF RFC 4234) is used for the syntax specification.

ABNF coding:

pathName = EphToken SLASH EPHsystem

EphToken = "Ephemeral" ; so called prefix

; The maximum length of ‘pathname’ is defined in Annex B.2/H.248.1.

EPHsystem = 0*(HierarchyLevelHIGHToken SLASH) HierarchyLevelLOWToken

HierarchyLevelHIGHToken = 1*alphanum

HierarchyLevelLOWToken = Individual / Wildcard

alphanum = ALPHA / DIGIT

Individual = 1*DIGIT

Wildcard = "$" / "*"

A.6.2 Multiplexed terminations

Table A.6.2/1: Multiplexed terminations

MultiplexTerminations Supported	Yes (NOTE)
NOTE : Yes for multimedia interworking and No for voice interworking.

Table A.6.2/2: Multiplex Types Supported

Multiplex types supported:	H.223
Maximum number of terminations connected to multiplex:	TBD (NOTE)
NOTE: It is not clear what is the exact purpose of this parameter; further clarification within H.248.1 core protocol is required before this property shall be used.