Telecommunications Industry Association
TR-30.1/02-06-076
(TIA)
Columbia, MD June 12- June 14, 2002
COMMITTEE CONTRIBUTION
Technical Committee TR-30 Meetings
SOURCE:
Conexant Sytems
CONTACT:
Frank Chen
Phone: +1 (949) 579-3296
Fax:
+1 (949) 579-3667
Email: frank.chen@mindspeed.com
TITLE:
Data Type Treatment in MoIP
PROJECT:
N/A
DISTRIBUTION:
Members of TR-30.1
____________________
ABSTRACT
This contribution discusses data type treatment in V.MoIP.
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and conditions for purpose of practicing a TIA Publication incorporates this contribution.
This document has been prepared by the Source Company(s) to assist the TIA Engineering Committee. It is proposed to the
Committee as a basis for discussion and is not to be construed as a binding proposal on the Source Company(s). The Source
Company(s) specifically reserves the right to amend or modify the material contained herein and nothing herein shall be
construed as conferring or offering licenses or rights with respect to any intellectual property of the Source Company(s) other
than provided in the copyright statement above.
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1.
Introduction
In a MoIP session, both PSTN links may establish connections with protocols such as LAPM,
V.14 or others. Depending on what types of connections it establishes, the data transferring across
IP network may have different meaning and need to be handled properly. As a generic protocol,
SPRT[1] should be capable of supporting different types of modem protocols. This contribution
proposes the different types of data that V.MoIP shall support and these data type treatment.
2.
References
[1] "Proposed Draft Text for D-005 version of V.MoIP ", TR-30.1/02-04-033, TIA TR-30.1
Technical Meeting, April 15, 2002, Albuquerque, NM.
[2] "Procedures for Supporting Non-Error Corrected connections in Modem Relay", TR30.1/02-04-052, TIA TR-30.1 Technical Meeting, April 15, 2002, Albuquerque, NM.
3.
Data Types
3.1. Generic Data Type
During a MoIP session, any data type may be sent under the generic data type. Any data sent as
generic data type shall be sent bit-by-bit and end-to-end without modification. This generic data
type shall not contain any local PSTN link control information. The data should be independent
of protocols and data formats.
3.2. LAPM Data Type
When a PSTN link establishes a LAPM connection, the gateway may send data as well as
LAPM specific information, such as address.
3.3. MNP4 Data Type
For gateway that establishes a MNP4 connection with its local modem, it may send MNP4 data.
3.4. V.14 Data Type
For a gateway that establishes an asynchronous non-error correction connection with its local
modem, the data sent to the IP network may fall into this category. SPRT shall support 10-bit
types defined in V.42 annex B as mandatory requirement. Data format of 8N1, 7E1 and 7O1
shall also be supported.
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3.5. Synchronous Data Type
For a gateway that establishes a synchronous non-error correction connection with local
modem, it may transmit data with this type over IP network[2].
3.6. RAW Data Type
When every bit from PSTN physical link is sent over IP link, it is considered as raw data. This
raw data type includes real data as well as local PSTN protocol related information. This raw
data type may be used when local PSTN protocol and data format is unknown.
4.
Data Transfer over SPRT
In order to send the above data types over an IP link and be recognized by the remote gateway,
a mechanism of carrying data with its data type and related information need to be provided. In
the following table a list of SPRT payloads is defined for the purpose of two gateways data
communication.
Table 1
5.
Information Messages in MoIP
SPRT MSG
Description
INFO_GENERIC
Generic data type
INFO_LAPM_DATA
LAPM data, including address field in I frame
INFO_MNP4_DATA
MNP4 data in LT frame
INFO_8N1_DATA
V.14 data, 8N1
INFO_7E1_DATA
V.14 data, 7E1
INFO_7O1_DATA
V.14 data, 7O1
INFO_SYNC_DATA
Synchronous, data
INFO_SYNC_EOF
Synchronous, end of frame
INFO_RAW
Raw data type
Data Type Negotiation
5.1. Data Type capability exchange
The data type support capability shall be exchanged between two gateways. Each gateway shall
advertise the data type it will support. Only data types that both gateways support may be sent
over IP link.
Data type capability exchange shall be included in SPRT INIT message and it shall be
exchanged before data is sent over IP link.
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Here is the proposed content that shall go in to SPRT INIT message: a 16 bits shall be used to
define the capability of data type support.
Bit
15…8
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
reserved
Raw
SYNC
V14
MNP4
LAPM
Generic
The default data type shall be the generic data type.
5.2. Transmit Data Type Negotiation
If both gateways have error correcting connection on PSTN link, the transmitter will decide
which data type it will use to send data over IP, as long as the data type is supported by the
other gateway.
When both gateways have non-error correcting protocol on PSTN link, gateway may send data
in raw type or other non-error correcting data type. A gateway shall negotiate with the other
gateway if it wants to use raw type after the PSTN connection is established and before the data
is sent. To serve this purpose, a “force raw type” flag shall be defined in SPRT CONN. If
either gateway set “force raw type” flag, both gateways shall send data in raw type over IP link,
giving that both gateways have the capability of supporting the raw type. Otherwise, the
gateway shall decide which data type it will use to send data over IP by itself.
When one gateway has error correcting connection on PSTN link and the other gateway has
non-error correcting protocol on PSTN link, each gateway will decide what data type it will use.
The raw type shall not be used.
6.
Data Transmit Channel
When data is sent over IP link, it may be sent over reliable channel 1 or unreliable channel 3 of
SPRT.
When a gateway has error correction connection on PSTN link, by default it shall send data on
SPRT channel 1 over IP link. The data over IP link will be error corrected and the data flow
control will be established on this data path. If both gateways consent the support of channel 3,
the gateway may send data on channel 3; otherwise, it sends data on channel 1. Once the
gateway decides which channel it will use, it shall not change the channel during this MoIP
session.
When a gateway has non-error correction connection on PSTN link, by default it shall send data
on SPRT channel 3 over IP link. If both gateways consent the support of channel 1, the gateway
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may send data on channel 1. The gateway that sends data over IP will decide which channel it
will use. Once the gateway decides which channel it will use, it shall not change the channel
during the MoIP session.
Two flags shall be provided in SPRT INIT for these consent purposes. A gateway may set
OPT_EC_ON_CH3 flag if it is willing to take data from channel 1 or channel 3 when remote
gateway is connected with error correcting protocol. A gateway may set
OPT_NONEC_ON_CH1 flag if it is willing to take data from channel 1 or channel 3 when
remote gateway is connected with non error correcting protocol.
7.
Data Type Determination
For non error correcting data type and data format, how a gateway knows the data type and
format of incoming PSTN data is implementation specific and out of the scope of V.moip
standard.
8.
Summary
It is therefore proposed that the committee agrees to the following;
To add the material presented in this contribution to
V.MoIP.
x.y
Agreed
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