Mitel Voice Processing Solutions Installation And Service Manual

							Dual Tl Digital Trunk Connectivity
Channel Associated Signaling (CAS)Release 6.0 digital trunk connectivity for 
Tl supports only channel-associated
signaling for ground start, loop start E 
& M, and DID trunks. Neither facility data
link (sometimes used with ESF) nor remote 
loopback requests are supported.
Note:
VoiceMemo Release 6.OA does not support common channel
signaling (CCS)
with Tl trunk connectivity. CCS is a method
where signaling for all channels is handled using a link that is
common to all channels (for example, SS7).
Signaling is channel associated (CAS)
where the signaling is handled individuallyinside each channel. Signaling information is carried in every sixth frame in a SF;
the ‘A’ and ‘B’ bits alternating every twelfth frame by borrowing (“robbing”) the least
significant bit from each channel. The “A” and “B” signaling bits each appear in
alternating superframes (that is, every twelfth frame). ESF signaling uses four
signaling bits, A, B, C, and D. These bits each repeat every twenty-fourth frame.
(In networks where ESF is not fully implemented, the C and D bits are not used and
the A and B are simply repeated.) Through the use of these two bits, four signaling
states can be transmitted (loop start, ground start, E 
& M, and DID).
Line CodingWhen transmitted, digital signals shift 
bemeen two voltages, typically some negative
voltage for one logic condition (-Vdc for “0” for example) and typically some
positive voltage for the other logical condition (+Vdc for “1” for example,). This
shift, known as a “bipolar shift.” where the signal shift does not linger at the zero
volts baseline is known as non-return to zero or 
NRZ. Transmission for long
distances over wire-based media of bipolar signals has a problem where the
transmission cable, which appears as a resonant circuit, integrates the DC voltage
(Figure 2-2) of the signal. This is especially true if the voltage remains at positive or
negative level for any length of time (as would be the case for a digital signal with a
series of 
“1” or “0” conditions in it). This charging of the transmission cable causes a
progressively smaller and smaller differential between logic 0 and 1 voltage
conditions. This then results in the inability of a receiving circuit to distinguish
between the logic conditions-a distinction that is imperative for recovering the
network clock.
To counteract this problem, several coding techniques have been developed to
balance plus 
(+) and minus (-) voltages (that is, prevent long strings of “l’s” or
“O’s”). The Series 6 server digital trunk interface can be configured to use one of
three of the more common coding techniques: alternate mark inversion 
(AMI), Ah41with zero code suppression (ZCS),and binary with 8 zeros suppression (BSZS).
2
2-4 
						

							Dud Tl Digital Trunk Connectivity
4-v--
ov
-v
-
Bit Stream Waveformof l’sof O’sx1686vm6Figure 2-2DC Voltage Shift in Digital Signal Transmission
AMIAM1 (alternate mark inversion) is a simple technique which 
conyerts a unipolar
signal into a bipolar signal. It also inverts the second (and the fourth, sixth, and so
forth) of a long string of 1 
‘s (Figure 2-3).
101010011000111001
a. Bit Stream Code
b. Binary Signal (Unipolar)Logic 1
Logic 0
II1In Logic 11 
I- Logic 0
c. Polar (NRZ)d. Bipolar 
(AMI-Alternate Mark Inversion)
Figure 2-3
AMI Line Coding
2-5 
						

							Dual T1 Digital Trunk Connectivity
AMI with ZCS
AM1 with zero code suppression is coding technique is similar to basic AM1 except
that the eighth 0 bit in a string of O’s is converted to a 
1 bit. This technique
interferes with the data when all zeros are transmitted. However, this is not a
significant problem when the data represents a voice signal and an occasional reversal
of a bit is not apparent in the overall voice signal quality.Of course, AM1 with ZCS
is a problem when transmitting data that requires a high degree of fidelity (for
example, video), but which is not a concern with voice messaging equipment.
B8ZS
B8ZS (bipolar with 8 zeros suppression) introduces a code, recognizable to a data
receiver, that a bit has been changed from a 0 to a 1. This technique deliberately
introduces a known bipolar violation 
(BPV) into a data stream.(A bipolar violation
occurs where a pulse is of the same polarity as the previous 
p&e.B8ZS deliberately
reverses the 
fifth and the seventh 0 in a series of eight 0 bits. The receiver recognizes
this known bipolar violation and substitutes the proper-data in its place. Because of
the predictable nature of 
B8ZS encoding, this encoding technique does not interfere
with the transmitted data. In the example shown in Figure 2-4, 
AM1 is used to code
1 
‘s; O’S are represented by a return to the baseline (that is, 0 volts).
Data ,
Sent10 0 0 0 0 0 0 0 0 1
BPVBPV
Line
-J-
Signal
-
x1867vm6I4Substituted Byte
c
Figure 2-4B8ZS line Coding
eThe Series 6 Server and TV-ApplicationsDigital trunk connectivity in a Series 6 server is available as a standard feature where
the system connects to the local switch through 
Tl digital trunks. A Series 6 server
module with digital connectivity has one or more 
Tl digital trunk interface cards
with one or more voice service cards (DSP24 cards, 
FaxMemo cards, and so forth).
Digital and analog trunks can coexist in the same Series 6 server. Such a mix could
be implemented in a Model 
I201 N-port configuration where the maximum
number of digital circuits allowed is 24 (that is, one 
Tl trunk) and the balance of
ports are analog trunks. 
						

							Dual Tl Digital Trunk Connectivity
Tl Connectivity FeaturesSeries 6 servers Model 
120s and Model 640 can support a total capacity of 60 KMvoice-application channels per module.
Note:“Port” as used elsewhere in Centigram Series 6 documentation,
when used in the context of digital trunk connectivity, equates
directly to “PCM channel,” “channel,” and “circuit.”
Series 6 server Model 640 and Model 
120s modules can support up to two Dual Tl
Digital Trunk Interface cards with two trunks per module for Series 6 
server-to-network connections (for example, for incoming-to-help line connections). A Model
1201 and a Model 70 can each support a single trunk. For redundancy, incoming
ports can be divided between two trunk interface cards, so long as the total port
capacity is not exceeded.
I
Tip:To optimize fault tolerance on your system, configure your trunks
with the voice application circuits evenly divided between each
trunk. Thus, in a module with four trunks, a single trunk going
out of service results in the loss of only one-fourth of your total
available circuits.For example, for a Model 640 equipped with four digital trunks (that is, two
Dual 
Tl Digital Trunk Interface cards), configure lines groups to
use only 15 ports (PCM channels) on each trunk.
The user can set line coding for AM1 (alternate mark inversion), 
AM1 with ZCS
(zero code suppression), or 
B8ZS (binary eighth 0 suppression). The trunk can be
disabled using the standard all-ones (AK) signal. By default, the clock is slaved to
the incoming PCM signal from the network on trunk 0.
Tl Connectivity Functional Operation
-,.From the standpoint of implementation, the 
Tl trunk is expected to be the primary
trunk interface to the local switch. The 
Tl Trunk Interface Card handles Tl frame
multiplexing and demultiplexing, clock extraction, and so forth. The 
Tl digital
trunk connectivity feature supports from one to four 
Tl trunks (with up to 60 ports)
per module to a single PBX or to a single CO.
On the receive side of the trunk (relative to the Series 6 server, the 
Tl Trunk
Interface Card demultiplexes the voice, overhead, and signaling time slots to recover
traffic data (voice information), framing bits, and signaling data.
For connectionsto differing 
PBXs, COs, or a mix of PBXs and COs with Tls, the
trunks should be connected to different modules.
2-7 
						

							Dual Tl Digital Trunk Connectivity
Dual Tl Trunk Interface CardThe Series 6 server uses a Model MB89 110 Dual 
Tl Trunk Interface Card. This
card is the interface for up to two (per card) 
Tl digital trunks. The interface card, an
AT bus-compatible adapter card, plugs into the server backplane in Series 6 Model
70, Model 1201 and Model 
12OS, and Model 640. The interface card supports
balanced (standard 
8-pin RJ-48C) trunk connections.
The 
Tl Digital Trunk Interface and the DSP24 line cards interconnect through the
MVIP bus (Figure 2-5). Configuration and line group assignments for both are
handled through the Configuration Manager (refer to TR 1903 in the Technical
Reference Manual for configuration information).
On the receive side of the trunk, the Dual 
Tl trunk interface card demultiplexes the
voice, overhead, and signaling time slots to recover traffic 
data*,(voice information),
framing and error checking bits, and signaling data. It passes the PCM bearer
channels with voice information and signaling (CAS) data to the Digital Signal
Processing line card. The line card connected to the Dual 
Tl trunk interface card by
way of the 
MVIP bus separates the voice data and CAS information from the PCM
data. The line card then forwards them to the 
VoiceMemo application running on
the CPU.
The Digital Signal Processing line card can be DSP24 or a 
DSPS. A DSP24 has 24
channels available to process the voice signal information from a full 
Tl trunk. The
DSP 8 cards, with 8 channels available to process the voice signal information, are
used to support fractional 
Tl configurations. Refer to TRlYOl for DSP8 line card
information and to TR1903 for DSP24 line card information in the 
Centigrdm
Series G Technical Reference Manual.On the transmit side of the trunk, for outgoing calls the DSP 24 line card formats
the outgoing voice data voice and signaling data from the CPU for the Dual 
TlTrunk Interface card.
MVIP Bus
PCM Channels 1-24Tl Trunks
Interface CardFax Card
Voice ChannelsFax Data
- tocpu 2Figure 2-5
Tl Digital Trunk Interface Connectivity
ij2-8 
						

							Dual Tl Digital Trunk Connectivity
Integration With Analog Trunk InterfacesThe 
Tl Digital Trunk Connectivity feature can coexist with analog trunks in the
same Series 6 server module. In such configurations, the voice channel cards will be
a mix of DSP24 or DSP8 line cards used in conjunction with a Dual 
Tl Trunk
Interface card), and LC8 line cards used in conjunction with the analog trunks.
Clock SynchronizationThe 
Tl clock can be synchronized either to a clock recovered from the network RxDsignal of one of the incoming trunks or to an internal clock reference (free-running
master clock source on the Dual 
Tl card). Both Tl carrier interfaces on the Dual
Tl card recover a 1.544 Mb/set clock and 8 kHz frame clock from the network Tlreceived signal (Rx). These recovered frame signals go to the on-card clock source
for use to synchronize the 
MVII? clock and frame clock to the TJ F&D from the
nenvork.An MVIP master clock is the actual source of the clock signals used by all cards
common to the MVIP bus.Only one master for each 
MVIP bus and only one active
8 
kHz frame reference are allowed. The Tl clock default source is the MVIP master
on digital trunk interface card number 0, derived from the trunk 0 
Tl Rx signal
(that is, the only digital trunk interface card present in the Model 70 and Model
1201). (Trunk numbering is 0 through 
3, starting with “0” on the first trunk card.)
Through the configuration manager, the reference source to the master clock is
selected offline. Sources include a free-running oscillator on the digital trunk
interface card and the network Rx signals (that is, from trunk 0 and trunk 1). 
Whenconnected either to a PBX or to a CO, the network clock is always the clock
reference.
Clock reference switching switchover is “hitless,”that is, the clock reference can be
manually or automatically switched over to a second source without affecting 
traffic.For digital trunk connectivity implementations where both trunks terminate in a
single Dual 
Tl Trunk Interface card, the Series 6 server provides automatic clock
source switchover in the event of trunk failure.On detecting a failure of the trunk
from which the clock source is derived, the Dual Trunk Interface card automatically
switches over to the second digital trunk (if the trunk in operation) on the card.
When connecting to channel banks, the Series 6 server module is the clock reference.
In this case, all 
Tl links to a particular channel bank come from the same Series 6
server module.Because clock references are independent for each Series 6 server module, the server
can connect to different COs, a CO/PBX combination, or different PBXs. These
different connections, however, must go to different Series 6 server modules and
must be the primary clock reference within their respective modules.
2-9 
						

							Dual Tl Digital Trunk Connectivity
Tl Digital Carrier Events
.When the Dual 
Tl digital trunk interface card detects failures on the trunk receive
data 
(RxD). When ar ures persists for more than 2.5 seconds, the VoiceMemof ‘1carrier alarm function automatically generates a remote alarm to the far end. For
such failures, the carrier alarm functionality informs the signaling function that ports
on a failed digital trunk are unavailable and terminates in-process calls. Only after a
trunk is restored for 10 seconds are the trunk ports again made available to the
VoiceMemo application. The server maintains these carrier events for each trunk:
lLoss of frame (LOS)
eFrame slips
lBit errors
lRemote Alarms
lAll one’s signal (AK)
lLocal carrier alarm
aRemote carrier alarm
lErrored seconds
lFailed secondsWhen the equipment is online, service personnel can monitor several digital trunk
conditions and control several functions. These include:
lDisplaying event counters, current trunk state, current clock source, and
trunk configuration for a single trunk or all trunks in a module.
eSetting the module clock reference.
lConnecting or disconnect a digital loopback toward the facility.
ePlacing a digital trunk out-of-service. This action returns an AIS to the
switch.
lRestoring a digital trunk to service.
Alarm Handling and Reporting
-The Tl digital trunk function in the Series 6 server recognizes and responds to out-
of-frame (OOF) 1
a arms,yellow alarms (D4 and ESF) red alarms, and blue alarms.
These alarm conditions are all recorded in the system event log. A 
VoiceMemomaintenance utility presents a Digital Carrier Status screen that shows event counters
where trunk error activity can be reviewed.
22-10 
						

							Dual Tl Digital Trunk ConnectivityOut-Of-Frame (OOF) Alarm
When the Dual Tl trunk interface card detects a loss of frame synchronizationit
immediately attempts to reframe. A loss of frame is determined to have occurred
when the received data framing bits are in error two bits out of four. When the loss
of frame occurs, the digital trunk interface driver (the interface control software)
tracks the length of time the framing is lost and notifies all affected applications of
the OOF condition.
Note:A Blue Alarm (an AIS) from the far end results in an OOF
condition.
Yellow Alarm
The Yellow Alarm signal indicates that a 
DSl connection has lost frame
synchronization.When the Dual Tl Digital Trunk Interface d$tects an incoming
Yellow Alarm, the affected 
Tl carrier goes into a Carrier Group Alarm state. The
Series 6 server module sends the alarm when the OOF condition has been detected
for a set minimum time threshold. The form of the yellow Alarm depends on the
framing format in use.For D4 framing, a Yellow Alarm consists of setting bit 2 in
every channel to zero. An ESF Yellow Alarm consists of the repeating 16-bit pattern:
0000 0000 1111 1111. The Dual 
Tl digital trunk interface card generates this
pattern on the command of the driver software.
These are the timing conventions associated with a Yellow Alarm signal:
1.The Dual Tl digital trunk interface detects an incoming out-of-frame
within 335 to 1000 milliseconds.
2.The out-of-frame persists for 2.5 seconds, after which a Yellow Alarm is
asserted.3.The Yellow Alarm is not cleared until the 
DSl signal has been reframed for
155 seconds.
4.The minimum time interval between the end of one Yellow Alarm and the
start of another is 1 second.
Blue Alarm
The Blue Alarm is an alarm indication signal 
(AIS) and consists of a continuous
string of unframed one’s (hence the derivative: “all l’s” or 
AIS). This signal is
typically used to indicate to the far end that some kind alarm condition exists. This
condition could be nothing more than the circuit removed from service for testing or
it could mean an equipment failure on the network. The transmission of all ones
permits the 
Tl clock to continue to be recovered from the network Rx signal in the
absence of traffic while still communicating the alarm condition.
When the 
Tl driver is advised of the AIS by the hardware, the affected Tl carrier
goes into an OOF condition. The 
VoiceMemo digital trunk connectivity software
treats the condition like any other OOF except for setting the user-accessible status
bits and an entry in the system error log that the alarm is a Remote Blue Alarm.
2-11 
						

							Dual Tl Digital Trunk ConnectivityRed Alarm
A Red Alarm is asserted and the affected 
Tl carrier goes to a Carrier Group Alarm
state when the 
Tl interface detects that an OOF has persisted for more than 230.5seconds. A Yellow Alarm is also asserted as long as the 
TI remains in a Red Alarm
condition.
Carrier Group Alarm (CGA)
The CGA consists of the local node either being in a Red Alarm state or of receiving
a Yellow Alarm from the far end.(The Yellow Alarm from the far end indicates that
the far end cannot frame on the near end signal.) The CGA is canceled when the
Red Alarm condition is removed or when the Remote Yellow Alarm is removed for
100 to 1000 milliseconds.
When then CGA state has been entered, the 
Tl digital trunk interface software logs
an error message in the system error 
logfile to indicating the CGA. It also sends
notice of the CGA to all applications affected by the T-l carrier.
Digital Trunk Status
The 
VoiceMemo digital trunk status maintenance utility presents a display of
summary counters that shows the occurrences of the following events:
Errored seconds where any event with at least one code violation within one
second.Out 
offame where ~0 or more framing bit errors out of 16 or fewer
consecutive framing “F” bits are detected within a 
$millisecond period.
Frame slips where the digital trunk interface looses frame synchronization.Also where the transmission facility or switch drops or repeats a frame
without loosing frame synchronization.
Alarm indication signals 
(AK) the transmission facility or switch sends to
indicate that a trunk has been put out-of-service from the network end.
Errored seconds where an errored second is any second with at least oneimpairment.
Failed second where an impairment lasted for an entire second.Bit 
emorf where the count represents the number of bits incorrectly
interpreted by the 
Tl line receiver in the digital trunk interface.
Local alarms is the count of the local alarms that have occurred during the
count period.
Remote alarms is the count of the remote alarms that have received during
the count period.
ConfigurationDigital trunk connectivity configuration is done off-line through the Physical
Resource Configuration Manager. After you have planned the system and the
i/2-12 
						

							Dual Tl Digital Trunk Connectivitymodule and physically installed the telephony card, configuration for adding a’ Dual
Tl card and for a digital trunk connection consists of the following:
lSelecting the physical slot assignment for the card.
lSetting the number of the module in which the card is installed.
lConfiguring the I/O port address of the card
lSetting the signaling used by the trunk.
lSetting the sequence number of the trunk.
lConfiguring the framing format (D4 or ESF).
lConfiguring the coding format for the 
KM bit stream (AMI, AMI with
ZCS, or BSZS).
Note:Its architecture being based on an AT bus, the server does sense in
which slot a card is installed. The 
VoiceMemo application
therefore must be “told” where the cards are in terms of a (logical)
slot assignment.Their slot assignments can be any unused slot
number (within the range of total possible physical slots). By
convention however, these 
logicalslot assignments map directly to
the 
physicalslot into which the cards reside.
In addition to this configuration, the trunk channels are assigned as ports in line
groups in the 
same manner as for a server equipped with analog trunks.
Procedure 
Cl? 3150 lists the steps for configuring a Dual Tl digital trunk interface
card.
Slot AssignmentThe Dual 
Tl Digital Trunk Interface card(s) are assigned (and factory-installed in)
specific physical slots in the Series 6 server backplane. The system software requires
these slot assignments to identify the hardware resources present in the backplane.
The configuration process for installing the digital trunk interface cards includes the
following:
1.2.
3.Configure the cards (refer to TR 1905 in this volume).
In the Physical Configuration Menu, configure the slots assigned to the
cards.In the Offline Menus, continue the configuration needed by the
applications.The factory installs the digital trunk interface card in these slots in Model 70, Model
120, and Model 640:
CardModel 70Model 1201Model 120sModel 640
Number Slot Number Slot Number Slot Number Slot Number
0
366
9
2-13