AT&T DS1/DMi/ISDN-PRI manual Data, Dmi

						INTRODUCTION	1-21
		TABLE 1-2.Data-Module Capabilities
Data	DMI	User Data	S y n c /	B i t	Protocol	Handshake	Notes
Module	M o d e	R a t e	A s y n c	Invert	Packaging
D T D M	2	300 - 19.2K	both	yes	H D L C	mode 2
MPDM	0	64K	sync	yes	n o	mode 2
	1	56K	sync	no	DDS	mode 2	1, 9
	2	to 19.2K	both	yes	H D L C	yes
MPDM/M1*	1	56K	sync	no	DDS	no	2, 9
	2	to 19.2K	both	yes	HDLC	no
3270 A	2	to 19.2K	both	yes	HDLC	mode 3/2 adapt	3
	3	64K	sync	yes	LAPD	mode 3/2 adapt	4
3270 T	3	6 4 K	sync	yes	LAPD	m o d e 3
PC/PBX	2	to 19.2K	both	yes	HDLC	mode 3/2 adapt	5
w/ASCII	3	64K	sync	yes	LAPD	mode 3/2 adapt
Term Emul
PC/PBX	3	64K	sync	yes	LAPD	mode 3
w/3270
Emulation
7500	0	64K	sync	no	no	no	6
U D M - T
	1	56K	sync	no	DDS	n o
	2	to 19.2K	both	yes	H D L C	mode 2	3
	3	64K	sync	yes	LAPD/X.25	mode 3/2 adapt	7, 8

MPDM — modular processor data module

NOTES:

1.A mode-2 handshake works only on 64K-bps facilities (such as robbed-bit). (Use an MPDM/M1* for mode-1 calls made over robbed-bit facilities.) Since an ISDN-PRI link between a System 85 R2V4 and a Generic 1 uses these facilities, this handshaking will work.

2.You must use the MPDM/M1* when the far end data circuit-terminating equipment (DCE) is not another AT&T data module (does not do a mode-2 handshake).

3.“Mode 3/2 adaptive” means that a mode-3 handshake is attempted first. An algorithm is then followed to determine the far-end's mode and either switch to mode 2 or continue in mode 3.

4.Mode-3 data can only be circuit switched in System 85 R2V4 and Generic 1.

5.Mode 2 on the PC/PBX Connection is supported under the ASCII terminal emulation package.

6.It is expected that an option switch will be added to the 7500 to invert or not invert.

7.On outgoing mode-3 calls, the 7500 does not invert bits. On incoming calls, the 7500 checks the low-layer compatibility IE and either inverts or does not invert depending on the contents of the IE.

8.The algorithm for the mode 3/mode 2 handshake is different for DCP data modules and BRI data modules, which could cause DCP/BRl interworking problems.

9.Bit inversion is administrable; “no” is the default value.

Some applications where DCP and DMI formatted data are not used include the following:

a. When 64K-bps data is transmitted across DS1/DMI/ISDN-PRI facilities (via a dedicated switch connection or DSC) to an endpoint such as a channel bank channel unit.

b.When a point-to-point data application is done with CDMs to drop and insert DS0 channels. Here, it is up to the user endpoints to ensure that the 1s-density requirement is met.