GTE Omni Si Database Technical Practices Issue 1 Manual

							TL-130500-1001
PDN
Telenet\PEC
bus
\LPB
\PCM
bus
Figure 32.2Synchronous Packet Manager Interface
For an X.25 packet to be transmitted to the data system, it must
be broken down into 1 l-byte packets, called mini-packets,
which adhere to the MPP (Mini-Packet Protocol) format. For
transmission from the PABX to the data network, mini-packets
are stored (buffered) until a full X.25 packet is formed and then
transmitted (see Figure 32.2).
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The SPM contains two 8-bit microprocessors, 80K of parity
protected RAM, and 8K of ROM. The SPM contains the mini-packet receiver/transmitter and line driver circuits used to
communicate with the PABX. The ROM in the SPM contains the
programs necessary to boot the SPM from the PABX, a
debugger, and limited hardware self-tests. The RAM in the
SPM is provides the operational code needed to communicate
with the data system, and is used for temporary storage, buffers,
and operational parameters. The SPM performs packet
assembler/disassembler functions and also contains the CRC
(Cyclic Redundant Checking) error detect logic.
The SPM contains the following switches and indicators:
* SWITCH LIKK Indicator.This indicator shows whether the
SPM is in a test condition or is receiving/transmitting 
mini-packets.
0 X.25 TEST ACTIVE Indicator. This indicator is off during
normal operation.When the TEST pushbutton is depressed
and diagnostic software is being downloaded from the system,
this indicator will be on.
l W25 TEST Pushbutton. This pushbutton is not operational for
this version.
r RESET Pushbutton. The RESET pushbutton causes a reset
condition when depressed.
@ DTE/DCE Switch. This two-position switch sets the SPM data
communications mode of operation. When depressed, the
SPM is in the DTE (Data Terminal Equipment) mode, allowing it
to be connected to terminal equipment. When released, the
SPM is in the DCE (Data Communication Equipment) mode,
allowing it to be connected to transmission lines.
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							TL-130500-1001DFP/APM (DIGITAL33.0 The DFP/APM provides voice communication as well as
FEATUREPHONEthe interface between the asynchronous data equipment
WITH APM)(terminals, personal computers, etc.) and the VPLC2 FB-17246
card.
The 
DFP/APM interfaces with the voice system over the PEC and
PCM buses and the data system over the LPB (Figure 33.1).
Connection to the VPLC2 (FB-17246-A) card is over a single
twisted pair. This connection supports both 
IJoice and data
communications. The DFP/APM is either locally or remotely
powered over a separate twisted pair connection.
Connection to the data device is provided by a standard 
RS-232-CN.24 interface, located in the rear of the phone.
Operating speeds of the data device can be 110. 300, 1200,
2400, 4800, 9600 baud, and 19,200 bps.
Contained within the 
DFP/APM are the 8-bit microprocessor,
memory, packet assembler/disassembler, transmit/receive
buffers, the CRC (Cyclic Redundant Check) error detect logic.
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							TL-130500-1001T+R
O-
Figure 33.1DFP/APM Voice and Data Bus Connection
.
7-
T+R
DFP/APM+1 
FB-228[Tl\LPB
’
DFP/APMTransmission33.1 Transmission of 11 -byte voice, data, and control
information is sent as mixed mini-packets. The 11 -byte 
mini-packets are transmitted at 128 Kbps in each direction. The
effective throughput is 64 Kbps voice, 19.2 Kbps data and
overhead= 128 Kbps in each direction.
See Table 33.1 for feature comparisons of the APM, SPM, and
DFP/APM. Tables 33.2 and 33.3 provide CCITTrecommendations and descriptions for the APM, SPM, and
DFP:APM.S-306
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DFPIAPM
mini-packets
dPLC2
Figure 33.2Transmission from the Digital FeaturephonetotheSystem
Simultaneous Voice33.2 The simultaneous voice and data structure is:
Packetizingand Datal Data device log-on
l Data call distinctive or simultaneous with voice call
l Data characters briefly buffered at Digital Featurephone
l Data characters packetized in 8-byte groups at Digital
Featurephone
l Preceded with two address bytes
e Followed with one CRC error-checking byte
l 11 bytes equal one mini-packet
When the mini-packet arrives at the VPLC2 (Voice Packet Line
Card) (Figure 
33.2), it is given two extra bytes providing “from”
information.
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digital bit stream
voice and data packets
CRC
(control)address
(control “to”)
MPP 11 bitsNetwork
Interface Card33.3 The NIC (Network Interface Card) bridges the LPB (Local
Packet Bus) and the PCM (Pulse Code Modulation) bus. This
provides data networking capabilities between systems across a
Tl network interface. HDLC (Higher Data Level Control) conveys
the data to/from the PCM bus while MPP (Mini-Packet Protocol)
conveys data to/from the LPB (Figure 33.3).
The NIC provides an X.25 communication link between a
circuit-switched 
Tl trunk line and a packet-switched
async/sync data line. The card indirectly interfaces to an outside
Tl line via internal circuit-switched connections on the PCM
bus. True intergrated voice and packet-switched data
networking capabilities are provided by this card (see Figure
33.4).The 
NIC’s responsibility is similiar to that of the SPM. However
some major physical differences between the NIC and the SPM
are:l The NIC occupies a complete slot space allowing it an ABI
(Arbitrated Bus Interface) and a PCM interface
l The NIC has 256K bytes of shared memory
l The NIC has DMA (Direct Memory Access) hardware support,
an associated new MPCC (Multiple Protocol Communication
Control) chip, and a new interrupt control mechanism.
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							TL-130500-1001Table 33.1 Feature Comparison
NOTES:* 1. For information on VPLC cards, see section 7.0.
* 2. 
SPMs can interface with an RS-232-C if speeds are below
19.2 Kbps.
* 3. Throughput will vary according to the PAD (Packet
Assembler/Disassembler) parameter settings and data
format.
* 4. For speeds 
> 9.6 Kbps up to 64 Kbps.
axrmum distance from switch-3000 feetat
ITT 
V.35interface
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							TL-130500-1001Table 33.1Feature Comparison (Continued)
s-31 0cket Assembler/
ontains CODECand other associated
I  circuitry
Table 33.2 CCITT Recommendations
FEATURENOTE: X.28 is the language by which an X.3
command is entered, converting 
async. data
into X.25 packets, thereby allowing the user to
enter information through the 
k:?yboard of the
data device attached to the APM
Interfaces externally to X.25 host or X.25
PDNS (Telenet)
8/‘87,
X
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							SW 52108187DEVICE
3FP/APM
EC-221 79-AAPM
L
I
1I
i
c
i
EC-221 78-ASPM
Type A
EC-221 78-BSPM
Type BTL-130500-1001
Table 33.3
DFP/AMP, APM, SPM Description
FEATURE
l Provides interface between asynchronous
data equipment and the system
l Receives and transmits W-232-C
compatible signals, converting them into
mini-packet protocol
lCommunicates with the system over a
single, twisted-wire pair
lSupports speeds up to 19.2 Kbps
l Provides interface between asynchronous
data equipment and the system
l Receives and transmit RS-232-C
compatible signals, converting them into
mini-packet protocol
lCommunicates with the system over a
single, twisted-wire pair
lSupports speeds up to 19.2 Kbps
lUsed for devices needing RS-232-C
interface
lSupports devices operating at speeds up
to 19.2 Kbps
lCommunicates with the system over a
single, twisted-wire pair
*Used for devices needing V.35 interface
lSupports devices operating at speeds up
to 64 Kbps
eCommunicates with the system over a
single, twisted-wire pair
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OMNI-SIPCM BusPD-200LPBCircuit
Switched 
-:;f-Packet
Switched
c-- Tl24 TlChannelst----- PD-200 -----i)Fiaure 33.4NIC Card within the 
OMNI SI Svstem’s Architecture
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-- -, - ---~- -_... -__-_._
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