ATT Definity Addendum 1 For Ds1, Dmi, Isdn Pri Instructions Manual

							DS1 TRANSMISSION AND CABLING3-7
Direct — Under 1310 Feet
If two DS1s are separated by no more than 1310 feet (or no more than 655 feet to the same DSX-1
cross-connect point), then they may be connected directly without the need of additional equipment.
The cross-connect point is generally not required and the connection may consist of a single continuous
1310 foot cable. Figure 3-2-A, On-Premises Metallic-Cable Configurations, shows this configuration.½
Because ANN11Ds, ANN11Es, TN722Bs, and TN767s contain components that suppress unwanted
emissions from a DS1, standard premises distribution system (PDS) cables may be used to interconnect
these interfaces. The PDS wiring may only be used when connecting directly between System 75 and
System 85 DS1s. Other equipment is not guaranteed to meet FCC emission requirements when used
with unshielded cable. Allowable PDS cables include the following cable types or their electrical
equivalents:½
l
lAll 24-gauge PDS cable
26-gauge PDS cable of types ARTM, BKTA, or AFTW
NOTE: A 26-gauge cable has different distance limitations from 24-gauge cable. ANN11Cs do
not contain components that suppress unwanted emissions. Therefore, when an ANN11C is
used (either at one or both ends of a connection), PDS cables cannot be used. Shielded
twisted-pair cable (DCC-5/24-TSA) is required.
Between 1310 and 4310 Feet
When the distance between DS1s exceeds 1310 feet, repeaters are required to regenerate the signal. If
the total distance is less than 4310 feet, NCTEs containing office repeaters may be used at each end of a
DS1 facility as shown in figure 3-2-B, On-Premises Metallic-Cable Configurations. Generally, the
repeater module is ordered separately from the NCTE. The repeater module circuit is then installed
within the NCTE housing as a part of the installation process.½
Office repeaters only regenerate signals that are received from the transmission line span. NCTEs must
be within 655 feet of their respective DS1 or the distance between the NCTEs should not exceed 3000
feet. Using NCTEs and office repeaters permits a total maximum distance of 4310 feet. NCTEs must
be powered by a DS1 line or an external DC power source. Each NCTE connects to its respective DS1,
DMI, or ISDN-PRI via a 15-pin D-connector on the rear of the NCTE.
NOTE: PDS cabling should not be used for connecting to or between NCTEs. For equipment
cabinet to NCTE connections, use DCC-5/24-TSA cables with appropriate connectors (such as
ED1E434-11, group 181, group 370, group 380, the combination of group 380 and group 506 when
connecting to a universal module, or H600 when connecting to a TN767) and applicable length.½
½
Greater Than 4310 Feet
When distance between DS1s is greater than 4310 feet, line repeaters are required. Line repeaters
regenerate the signal for both the receive and transmit directions. NCTEs and their associated DC
power supplies (if necessary) are also required for this configuration. NCTEs are used to provide power
to the line repeaters over the line.
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4 
						

							3-8DS1 TRANSMISSION AND CABLING
Line repeaters may be placed up to 3000 feet from the NCTEs, and line repeaters may be spaced up to
6000 feet apart. NCTEs must still be within 655 feet of their respective DS1s. When using two line
repeaters, DS1s can be up to 13,310 feet apart. This distance may be extended in increments of 6000
feet by using additional line repeaters. Figure 3-2-C, On-Premises Metallic-Cable Configurations, shows½
this configuration.
DS1DS1
655 FT655 FT
MAXIMUM
MAXIMUM
DSX-1 PHANTOM POINT
A. DIRECT DISTANCE OF 1310 FT OR LESS
NCTENCTE
DSX-1
DSX-1DS1OFFICE
REPEATEROFFICE
REPEATERDS1
655 FT
MAXIMUM655 FT
MAXIMUM 3000 FT OR LESS
B. DISTANCE OF 1311 FT TO 4310 FT
DSX-1
DS1NCTET1 LINE
REPEATER
655 FT
MAXIMUM3000 FT OR LESS
6000 FT OR LESS
DSX-1
DS1
NCTET1 LINE
REPEATER
655 FT
MAXIMUM3000 FT OR LESS
C. DISTANCE OF 4311 FT OR MORE½
Figure 3-2. On-Premises Metallic-Cable Configurations
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4 
						

							DS1 TRANSMISSION AND CABLING3-9
Off-Premises Cabling
When DS1s reside in different locations, they are typically connected via a transmission facility (such as
a metallic cable configuration) that is leased from the LEC. This facility usually consists of a line and
T1 repeater combination. The customer premises equipment interfaces to a DS1 network facility (T1
line) via NCTEs.
The customer is responsibility for maintaining NCTEs. When purchasing service from the LEC, the
customer must specify the DS1-framing and line-coding requirements.
For off-premises cabling, it is also possible to use any of the connection methods described for “On-
Premises Cabling” as long as appropriate lightning and powerline cross-protection is provided.
Echo on voice channels must also be considered when a DS1 facility extends over long distances (that
is, long round trip delays are encountered). Round trip delays of about 16-ms equate to about 100 miles
through the public switched network or 800 miles in a private network. Each digital switch and each
digital multiplexer in a path adds about 3-ms and 2-ms of delay respectively. Therefore, private network
routes with several digital switches and digital multiplexers may need to use echo cancelers in path
distances of less than 100 miles as shown in figure 3-3, On-Premises Metallic-Cable Configurations.½
½
½
For a fee, AT&T Toll Offices can add echo cancelers.
DSX-1
PROTECTION
DS1NCTE(NOTE)
CIRCUIT
655 FT
MAXIMUM
REPEATED
DS1 LINE
DSX-1PROTECTION
DS1
NCTE(NOTE)CIRCUIT
655 FT
MAXIMUM
NOTE: Use of the office repeater is optional depending on the distance to the first T1 repeater
(unless it is needed to supply loop power).½
Figure 3-3. Off-Premises Metallic Cable Configuration
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4 
						

							3-10DS1 TRANSMISSION AND CABLING
NONMETALLIC CABLING OPTIONS
Many alternatives to DS1 metallic transmission facilities exist. Some of these include systems that
transmit a DS1 signal on light-guide fiber, microwaves, infrared, and radio waves. All AT&T network
distribution systems (NDS) products are compatible. Other systems should be compatible with
System 75 and System 85 DS1s as long as the following conditions are met:½
lThe transmission system connects to a DS1 via a DSX-1 cross-connect
lThe transmission system meets any special requirements for the application (for example, the
transmission of bipolar violations if B8ZS line coding must be used)
Figure 3-4, Nonmetallic Cabling Configurations, shows nonmetallic cabling transmission systems.½
DSI/DMIMICROWAVEINTERFACEMICROWAVE
INTERFACE
LIGHT-GUIDE
INTERFACELIGHT-GUIDE
INTERFACE
DSX-1DSX-1
DS1
DS1
INFRARED
INTERFACE
INFRAREDINTERFACE
655 FT
MAXIMUM655 FT
MAXIMUM
ANY DSX-1
INTERFACEANY DSX-1
INTERFACE½
Figure 3-4. Nonmetallic Cabling Configurations
CEM AND CDM CABLING CONFIGURATIONS
Both the CEM and CDM provide a DSX-1 cross-connect to the DS1/DMI-BOS and therefore connect
directly to a DS1/DMI-BOS. Any of the previously described metallic or nonmetallic transmission
media may be used for completing the connection from a DS1/DMI-BOS to CEMs and CDMs. Figure
3-5, CEM and CDM Cable Configurations, shows stand alone and combined CEM and CDM
configurations.½
Refer to Service Manual — Installation and Maintenance — Channel Division Multiplexer (365-165-
101) and to BCM32000 — Description, Installation, and Maintenance — Digital Transmission Systems
(365-287-100) for appropriate distance limitations and switch settings.
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4 
						

							DS1 TRANSMISSION AND CABLING3-11
DS1/DMI
OR D4
CHANNEL
BANKDSX-1
DSX-1DS1/DMI
OR D4
CHANNEL
BANKCEMDSX-1ANY DS1
TRANSMISSION
MEDIADSX-1
CEM
DS1/DMI
OR D4
CHANNEL
BANKDSX-1DSX-1DS1/DMI
OR D4
CHANNEL
BANK
A. CEM ONLY
DS1/DMI
OR D4
CHANNEL
BANKDSX-1
CDM
CDM
DSX-1DS1/DMI
OR D4
CHANNEL
BANK DSX-1
ANY DS1TRANSMISSIONMEDIADSX-1DEDICATED
CHANNEL
APPLICATIONSCHANNEL
UNITSCHANNEL
UNITSDEDICATED
CHANNEL
APPLICATIONS
B. CDM ONLY
DS1/DMI
OR D4
CHANNEL
BANK
DSX-1
ANY DS1
TRANSMISSION
MEDIA
DSX-1DS1/DMI
OR D4
CHANNEL
BANK
CEM
CEM
(NOTE)DSX-1DSX-1
DS1/DMI
OR D4
CHANNEL
BANK
CDM
CDMDSX-1(NOTE)
DSX-1DSX-1DS1/DMI
OR D4
CHANNEL
BANK
DEICATED
CHANNEL
APPLICATIONSCHANNEL
UNITSCHANNEL
UNITSDEDICATED
CHANNEL
APPLICATIONS½
C. COMBINATION CDM AND CEM
NOTE: Requires the bundling signal option.
Figure 3-5. CEM and CDM Cable Configurations
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4 
						

							3-12DS1 TRANSMISSION AND CABLING
LINE EQUALIZER AND COMPENSATION SETTINGS
The Generic 1 and Generic 2 DS1 circuit packs generate a signal that is preequalized. Preequalized
means that the bipolar signal is shaped so that when it reaches the cable end it conforms to the DSX-1
power specification.½
½
System 85 Traditional Modules½
Traditional modules may be equipped with the ANN11 and ANN35 circuit packs. Preequalization is
provided by properly setting the three equalizer switches, on the circuit packs. The three switches must
be set for either half or all of the distance to the far end. The correct equalizer and compensation setting
is determined based on the cable configuration. If a DS1 terminates at a NCTE or DSX-1 cross-connect,
the total distance to the NCTE or DSX-1 should be used. If a DS1 terminates on another DS1, then half
the distance to the other interface should be used. This setting is done in increments of about 133 feet½
½
[see table 3-7, System85 Traditional Module Equalizer Settings (Metallic Cable)].
TABLE 3-7. System 85 Traditional Module Equalizer Settings (Metallic Cable)½
Distance to MidpointANN11, ANN35½
or Endpoint (FT)Switch Settings
22 AWG ABAM & 24 AWG PDS26 AWG PDS
12
3
0 to 133
ONOFF
133 to 266OFF
OFFON
266 to 3990 to 90
90 to 180
180 to 270
270 to 360
360 to 450ON
ONON
OFF
OFF
OFF
399 to 532
ON
ONON532 to 665OFF
NOTE: The ANN11 and ANN35 circuit packs only have three switches.
Off (1) is away from the switch number; on (0) is toward the switch number.½
½
Generic 1 and Generic 2 Universal Modules½
For TN722_ and TN767 circuit packs, preequalization is provided by properly administering the line
compensation field. Compensation adjustments are described in the appropriate Generic 1 and Generic 2
administration manuals.
Pinouts for the cables connecting these circuit packs are given in System85 R2V4 to DEFINITY
Communications System Generic 1.1 via ISDN PRI Access (555-037-233), DEFINITY Communications
System Generic 1.1 to 4ESS via ISDN PRI Access (555-037-234), and DEFINITY Communications
System Generic 2.1 to 4ESS via ISDN PRI Access (555-037-237).½
½
½
½
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4 
						

							SYNCHRONIZATION OF DIGITAL FACILITIES5-29
CONCLUSIONS ON SYNCHRONIZATION
Make no assumptions regarding synchronization. Reverify items such as the availability of a
synchronization source, the clock stratum, and compatibility of every T1 span. The best guarantee is
written confirmation that the local exchange carrier, AT&T Communications, or other vendor will either
synchronize to a System 75, System 85, Generic 1, Generic 2, or provide an appropriate synchronization
reference.½
Develop a diagram showing the network synchronization plan. Make multiple copies of this diagram
and keep a copy at each switch site. This diagram is essential for installing, administering, and tuning
up a DS1 network. Such a diagram can also be used by maintenance personnel to troubleshoot network
problems associated with synchronization.½
A properly designed synchronization plan will improve the quality and reliability of a digital private
network. If designing a synchronization plan becomes too complex or if many applications have a
crucial dependency on the digital facilities, then the AT&T Synchronization Design Service should be
consulted.½
½
½
USE OF GENERIC 2 AS A SYSTEM CLOCK REFERENCE
To provide increased reliability, it is recommended that (for all cases) the primary and secondary system
clock references be placed in different modules. Tips on how best to use a DS1 as a clock reference are
provided next.½
½
ISDN-PRI Trunk Facilities
ISDN-PRI trunks may terminate on a 4ESS toll office, 5ESS digital CO, System 85 R2V4, Generic 1,
Generic 2, or compatible vendor’s switch. Depending on other considerations, any of these terminating
connections may be selected as either a primary or secondary synchronization reference. ISDN-PRI
configurations may be established with an ANN35 or with a TN767 with or without a TN555,
depending upon the D-channel configuration of the TN767. A brief description of these three boards½
½
½
½
½
½
½
and their general use for ISDN-PRI is given next.
The ANN11 is the DS1 board used with all System 85s and with traditional modules in Generic 2. The
ANN35 is the ISDN-PRI board used with System 85, R2V4, and Generic 2 traditional modules. The
TN767 is the DSl/ISDN-PRI board used with System 75, Generic 1, and Generic 2 universal modules.
The TN555 is the packet adjunct used with Generic 2 universal modules. If the TN767 has a D-channel
on it, it needs a TN555 located in the adjacent virtual slot.½
½
½
½
½
Line-Only Mode DS1/DMI-BOS (ANN11 or TN767)½
When using a line-only mode interface for synchronization purposes, the following facts should be
known:
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4 
						

							5-30SYNCHRONIZATION OF DIGITAL FACILITIES
l
lSince the D4-channel bank (or equivalent) at the far end will be timed to the signal received from a
DS1, no slips should occur on a line-only mode DS1 facility. Because of this, slip counts from
line-only mode DS1s should not be used to determine the health of a clock reference (that is, they
would tend to make the reference appear to be in better condition than it may be).½
Line-only mode DS1s should not be used as system clock references unless it is known for certain
that the incoming DS1 is locked to the AT&T reference frequency. Normally, a DS1 facility
terminating directly on a far-end D4-channel bank is not locked to the AT&T reference frequency.½
Line+Trunk Mode DS1/DMI-BOS (ANN35 or TN767 with TN555)
Regarding the use of a line+trunk mode DS1/DMI-BOS for synchronization, the following point should
be noted. Since it would be expected that a line+trunk mode DS1 would terminate at a class-5 or higher
CO or at another switch, the line+trunk interface should be suitable for use as a primary or secondary
clock reference (or to be the timing master for another switch).
The slip count provided by the interface should also be used in the process of choosing a healthy clock
reference. However, when the interface terminates on a D4-channel bank (or equivalent) that is not
locked to the AT&T reference frequency for its timing, then the interface should not be used for
synchronization.½
DMI-MOS (ANN35 or TN767 with TN555)½
System 85 DSl/DMI-MOS (ANN35) will only terminate at a compatible computer. The computer must
always obtain its timing from the switch. The switch should never select the DMI-MOS link as a
timing reference.
Although those circuit packs that support connections to remote modules operate at the DS1s rate, they
are not the same as the DS1/DMI/ISDN-PRI. Remote module connections cannot be used as a clock
synchronization reference.
USE OF GENERIC 1 AS A SYSTEM CLOCK REFERENCE
To provide increased reliability, it is recommended that (for all cases) the primary and secondary system
clock references be placed in different modules. Tips on how best to use DS1s as a clock reference are
provided next.½
Trunk-Mode ISDN-PRI (TN767)
ISDN-PRI trunks may terminate on a 4ESS toll office, 5ESS digital CO, System 85 R2V4, Generic 1,
Generic 2, or compatible vendor’s switch. Depending on other considerations, any of these terminating
connections may be selected as a primary or secondary synchronization reference.½
½
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4 
						

							SYNCHRONIZATION OF DIGITAL FACILITIES5-31
Trunk-Mode Interface (ISDN-PRI + Robbed Bit) (TN767)
Since it is expected that a trunk mode DS1 would terminate at a class-5 or higher CO or at another
switch, the trunk interface should be suitable for use as a primary or secondary clock reference (or to be
the timing master for another switch).*
The slip count provided by the interface should also be used in the process of choosing a healthy clock
reference. However, when the interface terminates on a D4-channel bank (or equivalent) that is not
locked to the AT&T reference frequency for its timing, then the interface should not be used for
synchronization.
Line-Only Mode DS1/DMI-BOS (TN767)
When using a line-only mode interface for synchronization purposes, the following facts should be
known:
l
lSince the far-end D4-channel bank (or equivalent) is timed to the signal received from a DS1/DMI,
no slips should occur on a line-only mode DS1/DMI facility. Because of this, slip counts from line-
only mode DS1/DMI should not be used in the process of determining the health of a clock
reference (that is, they would tend to make the reference appear to be in better condition than it may
be).½
Line-only mode DS1/DMI should not be used as system clock references unless it is known for
certain that the incoming DS1/DMI signal is locked to the AT&T reference frequency. Normally, a
DS1/DMI facility terminating directly on the far-end D4-channel bank is not locked to the AT&T½
reference frequency.
Trunk-Mode DS1/DMI-MOS (TN767)
For Generic 1, DS1/DMI-MOS (TN767) will only terminate at a compatible computer. The computer
must always obtain its timing from the switch. The switch should never select the DMI-MOS link as a
timing reference.
NOTE: For Generic 1, the TN722 may be used instead of the TN767 for non-ISDN applications.½
½
½
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4 
						

							5-32SYNCHRONIZATION OF DIGITAL FACILITIES
ADDENDUM 1 (December 1990) to 555-025-101, Issue 4