Telecommunications Industry Association
(TIA)
TR-30.1/1-02-08-111
August 6-9, 2002, Waltham, MA
COMMITTEE CONTRIBUTION
Technical Committee TR-30 Meetings
SOURCE:
The CommWorks Corp., a 3Com company
TITLE:
MoIP modem relay octet and bit raw compressed data message formats
DISTRIBUTION:
Members of TR-30.1
CONTACT:
Jim Renkel
Office: +1.847.262.2539
E-mail: james_renkel@commworks.com
____________________
ABSTRACT
This contribution documents the format of octet and bit compressed raw data messages for use in MoIP
modem relay mode, developed in the TR-30.1 committee meeting August 8, 2002.
COPYRIGHT STATEMENT:
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incorporate text or other copyrightable material contained in this contribution and any modifications thereof in the
creation of a TIA Publication; to copyright and sell in TIA's name any TIA Publication even though it may include all
or portions of this contribution; and at TIA's sole discretion to permit others to reproduce in whole or in part such
contributions or the resulting TIA Publication. This contributor will also be willing to grant licenses under such
copyrights to third parties on reasonable, non-discriminatory terms 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.
Telecommunications Industry Association (TIA)
August 6-9, 2002, Waltham, MA
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Table of Contents
Introduction ............................................................................................................................................ 3
Message common format ...................................................................................................................... 3
Octet compressed data segment ........................................................................................................... 4
Bit compressed data segment ............................................................................................................... 5
Table of Figures
Figure 1 - Octet and bit compressed raw data message common format .................................................... 3
Figure 2 - Octet compressed data segment format ...................................................................................... 4
Figure 3 - Bit compressed data segment format ........................................................................................... 5
3Com / CommWorks
MoIP modem relay octet and bit raw compressed data message formats
TR-30.1/1-02-08-111
Telecommunications Industry Association (TIA)
August 6-9, 2002, Waltham, MA
1
Page 3 of 5
Introduction
On August 8, 2002, in the TR-30.1 committee meeting in Waltham, Massachusetts, the committee
members collaborated in developing octet and bit compressed raw data messages for use in MoIP
modem relay mode. This contribution documents those messages.
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Message common format
The format of these messages is given in the following figure.
r msgID
segment
...
segment
Figure 1 - Octet and bit compressed raw data message common format
In these message:
r
msgID
segment
is a 1 bit field reserved for future use by the ITU-T. Message senders shall set
this field to 0. Message receivers shall ignore the value of this field.
is a 7 bit field whose value identifies the message; unique values are
assigned to the octet compressed raw data message and the bit compressed
raw data message.
is an octet or bit compressed data segment
Each message consists of the reserved field, the message ID field and one or more segments. The
reserved and message ID field together comprise one octet. Each segment contains an integral number
of octets. The length of the message, exclusive of transport protocol headers, is the sum of the lengths of
the segments plus one.
If the message is an octet compressed raw data message or bit compressed raw data message, each
segment in the message shall be an octet compressed data segment or a bit compressed data segment,
respectively.
The data represented by a raw data message shall consist of the concatenation of the data represented
by the compressed data segments of the message, in the order that the segments appear in the
message.
The data represented by an octet compressed raw data message is an integral number of octets. The
data represented by a bit compressed raw data message may not be an integral number of octets.
3Com / CommWorks
MoIP modem relay octet and bit raw compressed data message formats
TR-30.1/1-02-08-111
Telecommunications Industry Association (TIA)
August 6-9, 2002, Waltham, MA
3
Page 4 of 5
Octet compressed data segment
The formats of an octet compressed data segment are given in the following figure.
0
L
octet
...
octet
1
L
N
octet
...
octet
Figure 2 - Octet compressed data segment format
In these segments:
L
N
octet
is a 7 bit field whose value is one less than the number of octets in the
segment
is a 1 octet field whose value is two less than the number of times the octets
of the segment appear in the data represented by the message in which the
segment appears
is an octet of octet compressed data
The data represented by the first format of an octet compressed data segment is the data in the octets
contained in the segment. The represented data is an integral number of octets in length.
The data represented by the second format of an octet compressed data segment is the data in the octets
contained in the segment, repeated the indicated number of times. The represented data is an integral
number of octets in length.
3Com / CommWorks
MoIP modem relay octet and bit raw compressed data message formats
TR-30.1/1-02-08-111
Telecommunications Industry Association (TIA)
August 6-9, 2002, Waltham, MA
4
Page 5 of 5
Bit compressed data segment
The formats of a bit compressed data segment are given in the following figure.
00
L
octet
...
octet
01 L
P
octet
...
octet
1 L
P
N
octet
...
octet
Figure 3 - Bit compressed data segment format
In these segments:
L
P
N
octet
is a 6, 3, or 4 bit field whose value is one less than the number of octets in the
segment
is a 3 bit field whose value is the number of low order bits in the last octet that
are NOT in the data represented by this segment
is a 1 octet field whose value is two less than the number of times the octets
of the segment appear in the data represented by the message in which the
segment appears
is an octet of bit compressed data
The data represented by the first format of a bit compressed data segment is the data in the octets
contained in the segment. The represented data is an integral number of octets in length.
The data represented by the second and third formats of a bit compressed data segment is the data in
the octets contained in the segment, less the indicated number of low order bits in the last octet, repeated
the indicated number of times. The represented data is not necessarily an integral number of octets in
length.
3Com / CommWorks
MoIP modem relay octet and bit raw compressed data message formats
TR-30.1/1-02-08-111