Patton electronic Network Router 2720 I Series User Manual

USER  
MANUAL  
MODEL 2720/I Series  
NetLink-T1™  
T1/Fractional T1 CSU/DSU  
Part# 07M2720I-UM  
Doc#08618U2-001,  
Rev. B  
SALES OFFICE  
(301) 975-1000  
TECHNICAL SUPPORT  
(301) 975-1007  
Revised 10/26/06  
Copyright © 2006  
Patton Electronics Company  
All Rights Reserved  
An ISO-9001  
Certified Company  
 
1.3 INDUSTRY CANADA NOTICE  
RJ48. The Facility Interface Codes (FIC) are 04DU9-BN, 04DU9-DN,  
04DU9-1KN, and 04DU9-1SN. The Service Order Code (SOC) is 6.0N.  
The Canadian Department of Communications label identifies cer-  
tified equipment. This certification means that the equipment meets  
certain telecommunications network protective, operational and safety  
requirements. The Department does not guarantee the equipment will  
operate to the user's satisfaction. Before installing this equipment,  
users should ensure that it is permissible to be connected to the facili-  
ties of the local telecommunications company. The equipment must  
also be installed using an acceptable method of connection. In some  
cases, the company’s inside wiring associated with a single line individ-  
ual service may be extended by means of a certified connector assem-  
bly (telephone extension cord). The customer should be aware that  
compliance with the above condition may not prevent degradation of  
service in some situations. Repairs to some certified equipment should  
be made by an authorized maintenance facility designated by the sup-  
plier. Any repairs or alterations made by the user to this equipment, or  
equipment malfunctions, may give the telecommunications company  
cause to request the user to disconnect the equipment. Users should  
ensure for their own protection that the ground connections of the  
power utility, telephone lines and internal metallic water pipe system,  
are connected together. This protection may be particularly important  
in rural areas.  
1.5 SERVICE INFORMATION  
All warranty and non-warranty repairs must be returned freight  
prepaid and insured to Patton Electronics. All returns must have a  
Return Materials Authorization number on the outside of the shipping  
container. This number may be obtained from Patton Electronics  
Technical Support at: tel: (301) 975-1007 email:  
Packages received without an RMA number will not be accepted.  
Patton Electronics' technical staff is also available to answer any ques-  
tions that might arise concerning the installation or use of your Patton  
Model 2710RC. Technical Support hours: 8AM to 5PM EST, Monday  
through Friday.  
1.6 CE NOTICE  
The CE symbol on your Patton Electronics equipment indicates  
that it is in compliance with the Electromagnetic Compatibility (EMC)  
directive and the Low Voltage Directive (LVD) of the European Union  
(EU). A Certificate of Compliance is available by contacting Technical  
Support.  
1.4 FCC INFORMATION  
CAUTION: Users should not attempt to make such connections  
themselves, but should contact the appropriate electric inspection  
authority, or electrician, as appropriate.  
The Model 2720 Series has been tested and registered in compli-  
ance with the specifications in Part 68 of the FCC rules. A label on the  
equipment bears the FCC registration number. You may be requested  
to provide this information to your telephone company. Your telephone  
company may make changes in its facilities, equipment, operations or  
procedures that could affect the proper operation of the Model 2720  
Series. If this happens, the telephone company should give you  
advance notice to prevent the interruption of your service. The tele-  
phone company may decide to temporarily discontinue your service if  
they believe your Model 2720 Series may cause harm to the telephone  
network. Whenever possible, they will contact you in advance. If you  
elect to do so, you have the right to file a complaint with the FCC. If  
you have any trouble operating the Model 2720 Series, please contact  
Patton Electronics Technical Support 301-975-1000. The telephone  
company may ask you to disconnect the equipment from the telephone  
network until the problem has been corrected or until you are certain  
that the Model 2720 Series is not malfunctioning. In accordance with  
FCC rules and regulation CFR 47 68.218(b)(6), you must notify the  
telephone company prior to disconnection. The following information  
may be required when applying to your local telephone company for  
leased line facilities. The Universal Service Order Code (USOC) is  
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2.0 GENERAL INFORMATION  
3.0 PPP Operational Background  
Thank you for your purchase of this Patton Electronics product. This  
product has been thoroughly inspected and tested and is warranted for One  
Year parts and labor. If any questions arise during installation or use of the  
unit, contact Patton Electronics Technical Services at (301) 975-1007.  
PPP is a protocol used for multi-plexed transport over a point-to-point  
link. PPP operates on all full duplex media, and is a symmetric peer-to-peer  
protocol, which can be broken into three main components: 1. A standard  
method to encapsulate datagrams over serial links; 2. A Link Control  
Protocol (LCP) to establish, configure, and test the data-link connection; 3. A  
family of Network Control Protocols (NCPs) to establish and configure dif-  
ferent network layer protocols.  
In order to establish communications over a point-to-point link, each end  
of the PPP link must first announce its capabilities and agree on the param-  
eters of the link’s operation. This exchange is facilitated through LCP  
Configure-Request packets.  
Once the link has been established and optional facilities have been  
negotiated, PPP will attempt to establish a network protocol. PPP will use  
Network Control Protocol (NCP) to choose and configure one or more net-  
work layer protocols. Once each of the network layer protocols have been  
configured, datagrams from the established network layer protocol can be  
sent over the link. The link will remain configured for these communications  
until explicit LCP or NCP packets close the link down, or until some external  
event occurs.  
2.1 FEATURES  
Terminates T1/FT1 Circuits over a 4-Wire RJ-48C interface  
• 10Base-T Ethernet bridge  
• PPP (Point to Point Protocol, RFC 1661) with Bridge Control  
Protocol (RFC 1638)  
• Unstructured Rates at 1.544 Mbps  
• D4 or ESF Framing Modes  
• Supports AMI or B8ZS/B7ZS Line Coding  
• Configuration via Software Control Port or Internal DIP Switches  
• Six Easy-to-Read LED Indicators Monitor Data & Diagnostics  
• Internal, External or Receive Recover Clocking  
• Also Operates as a High-Speed Point-to-Point Modem  
• Made in USA  
The PPP Bridging Control Protocol (BCP), defined in RFC 1638,  
configures and enables/disables the bridge protocol on both ends of  
the point-to-point link. BCP uses the same packet exchange mecha-  
nism as the Link Control Protocol (LCP). BCP is a Network Control  
Protocol of PPP, bridge packets may not be exchanged until PPP has  
reached the network layer protocol phase.  
2.2 GENERAL PRODUCT DESCRIPTION  
The NetLink-T1™ Model 2720 Series are single port T1/FT1  
CSU/DSUs that provide high-speed WAN connectivity. Plugging directly into  
the serial WAN port of a switch, router or multiplexer, the NetLink-T1™ pro-  
vides T1 or FT1 access at connection data rates of 1.544 Mbps, nx64, and  
nx56 (n=1 to 24 channels). The Netlink-T1™ is an excellent choice when  
terminating leased line services, Frame Relay backbones, internet access  
as well as LAN-to-LAN services.  
3.1 APPLICATIONS  
In situations where a routed network requires connectivity to a  
remote Ethernet network, the interface on a router can be configured  
as a PPP IP Half Bridge. The serial line to the remote bridge functions  
as a Virtual Ethernet interface, effectively extending the routers serial  
port connection to the remote network. The bridge device sends bridge  
packets (BPDU's) to the router's serial interface. The router will receive  
the layer three address information and will forward these packets  
based on its IP address.  
Figure 1 shows a typical Cisco router with a serial interface configured  
as a PPP Half Bridge. The router serial interface uses a remote device that  
supports PPP bridging to function as a node on the remote Ethernet net-  
work. The serial interface on the Cisco will have an IP address on the  
same Ethernet subnet as the bridge.  
The Netlink-T1™ provides digital access to a local WAN service  
provider or directly between two facilities over a dedicated 4-Wire circuit.  
WAN bandwidth, framing and coding options are programmed via externally  
accessible DIP switches or via a VT-100 type terminal using the rear-  
mounted EIA-232 Control Port. Netlink-T1™ supports D4/ESF framing  
options and AMI/B8ZS/B7ZS line coding. Netlink-T1™ also supports a full  
range of system and diagnostic features that make system setup easy.  
The NetLink-T1™ provides T1 terminations over a modular RJ-48C jack  
and comply with jitter tolerance capabilities as specified in ANSI T1.403 and  
AT&T TR62411. External power options include 120VAC and universal  
interface 100-240VAC. 48VDC and rack card versions are also available.  
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Patton  
2701/I  
Bridge  
3.1.1 Switch S2  
The table below shows the default configurations for Switch S2. A  
Router  
description of all S2 options follows this table.  
Ethernet LAN  
S2 SUMMARY TABLE  
PEC Device w/ Serial I/F  
Position  
S2-1  
S2-2  
S2-3  
S2-4  
S2-5  
S2-6  
S2-7  
S2-8  
Function  
Data Rate  
Factory Default Selected Option  
Figure 1. Cisco router with serial interface, configured as PPP Half Bridge.  
On  
1.536 Mbps  
(DTE Rate)  
For example, the customer site is assigned the addresses  
192.168.1.0/24 through 192.168.1.1/24. The address 192.168.1.1/24 is  
also the default gateway for the remote network. The above settings  
remove any routing/forwarding intelligence from the CPE. The associ-  
ated Cisco configuration will set serial interface (s0) to accommodate  
half bridging for the above example.  
Authentication is optional under PPP. In a point-to-point leased-  
line link, incoming customer facilities are usually fixed in nature, there-  
fore authentication is generally not required. If the foreign device  
requires authentication via PAP or CHAP, the PPP software will  
respond with default Peer-ID consisting of the units Ethernet MAC  
address and a password which consists of the unit’s Ethernet MAC  
address.  
Some networking systems do not define network numbers in pack-  
ets sent out over a network. If a packet does not have a specific desti-  
nation network number, a router will assume that the packet is set up  
for the local segment and will not forward it to any other sub-network.  
However, in cases where two devices need to communicate over the  
wide-area, bridging can be used to transport non-routable protocols.  
Figure 2 illustrates transparent bridging between two routers over  
a serial interface (s0). Bridging will occur between the two Ethernet  
Interfaces on Router A (e0 and e1) and the two Ethernet Interfaces on  
Router B (e0 and e1).  
Data Rate  
On  
Data Rate  
On  
ESF/B8ZS  
64 kbps  
Framing & Coding  
DS Zero Rate  
Clock Mode  
Clock Mode  
Reserved  
Off  
On  
Off  
Off  
Off  
Network  
Network  
Reserved  
Switches S2-1, S2-2, and S2-3  
Use Switches S2-1, S2-2 and S2-3 to set the DTE data rate.  
Each setting represents an nx56/nx64 setting. Individual channel set-  
tings can be configured through the software control port.  
S2-1  
Off  
On  
Off  
On  
Off  
On  
Off  
On  
S2-2  
Off  
Off  
On  
On  
Off  
Off  
On  
On  
S2-3  
Off  
Off  
Off  
Off  
On  
On  
On  
On  
Speed  
Clear Channel (Unframed)  
112kbps/128kbps  
224kbps/256kbps  
336kbps/384kbps  
448kbps/512kbps  
672kbps/768kbps  
896kbps/1024kbps  
1344kbps/1536kbps  
2701/I  
!
Serial Interface  
E1/FE1 Link  
no ip routing  
!
Router A  
interface Ethernet0  
ip address 1.1.1.1 255.255.255.0  
bridge-group 1  
!
interface Serial0  
ip address 1.1.1.1 255.255.255.0  
encapsulation PPP  
bridge-group 1  
S0  
e0  
Switch S2-4: Line Framing and Coding  
LAN  
Use Switch S2-4 to control the Network Line Framing and Coding  
Options. Set these options to be the same as the Line Framing and  
Coding Options given to you by your Service Provider. If you are using  
two Model 2720s together as short range modems, set both units iden-  
tically.  
S1  
Using Bridge-Groups, multi-  
ple remote LANs can be  
bridged over the wide-area.  
LAN  
Router B  
S1  
!
S0  
interface Serial1  
ip address 2.2.2.2 255.255.255.0  
bridge-group 1  
!
bridge 1 protocol ieee  
!
e0  
e1  
LAN  
S2-4  
Off  
Line Framing & Coding  
ESF/B8ZS  
LAN  
LAN  
2701/I  
Serial Interface  
On  
D4/AMI  
E1/FE1 Link  
Figure 2. Transparent bridging between two routers over a serial interface.  
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Line Framing Options:  
Switch S2-6 and S2-7: Clock Mode  
D4/Superframe: The D4 framing format, as specified in AT&T  
TR62411 is the standard in which twelve frames make up a  
superframe. All signaling and synchronization are done in-  
band.  
Set Switch S2-6 and S2-7 to determine the 2720’s transmitter tim-  
ing.  
S2-6  
Off  
S2-7  
Off  
Clock Mode  
Network Clock. Transmitter timing is  
derived from the received line signal.  
Internal Clock. Transmitter clock is  
derived from an internal oscillator.  
Extended Superframe (ESF): Extended Superframe, as speci-  
fied in AT&T TR 54016, consists of twenty-four (24) T1  
frames. The framing bits are now used for framing, CRC and  
the Facility Data Link (FDL). The FDL allows maintenance  
messages and information to be passed between the 2720  
and the Central Office.  
On  
Off  
NOTE 1: When using the Model 2720 as a high-speed short  
range modem, one unit of the link must be configured in Internal  
Clock mode, and the opposite end unit must be configured for  
Network Clock mode.  
Line Coding Options:  
Alternate Mark Inversion (AMI): This mode does not inherently  
account for ones density. To meet this requirement, each time  
slot can be reduced to 56 kbps and the Least Significant Bit  
(LSB) of each time slot set to one.  
If the ERR LED on the front of the unit is flashing (or on) it could  
be an indication of a clocking problem. Double check your clock  
mode settings and Tx Clock Invert S1-3 settings.  
Switch S2-8 Reserved  
Bipolar 8 Zero Substitution (B8ZS): This mode assures proper  
bit density in the data stream. In this mode any data pattern  
can be transmitted without causing ones density errors. This  
mode allows for 64 kbps clear channel timeslots.  
Switch S2-5: DS0 Channel Rate  
Use Switch S2-5 to set the DS0 rate.  
SW2-5  
Off  
On  
Setting  
56 kbps  
64 kbps  
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3.1.2 Switch S1  
Switch S1-3: Tx Clock Invert  
The chart below shows the default configurations for Switch S1. A  
description of all S1 options follows this table.  
Switch S1-3 allows the user to invert the transmit clock originating  
in the 2720. When S1-2 is set for transmit clock, it may be necessary  
to invert the transmit clock to allow for delays due to long cables.  
S1 SUMMARY TABE  
Position  
S1-1  
Function  
RDL Type  
Factory Default Selected Option  
V.54 RDL  
On  
S1-3  
On  
Off  
Tx Clock Invert  
Transmit clock is inverted  
Transmit clock is normal  
S1-2  
Reserved  
On  
Normal  
S1-3  
Tx Clock Invert  
Line Build Out  
Off  
Switches S1-4 and S1-5: Line Build Out  
S1-4  
Off  
0dB  
S1-5  
Off  
Off  
Use Switches S1-4 and S1-5 to set the Line Build Out (LBO). The  
Line Build Out varies the pulse shape and attenuation of the signal  
sent to the network. The amount of Line Build Out depends on  
NetLink™ T1’s distance to the last repeater. The telephone company  
providing the service will advise on the amount of LBO necessary. In  
most cases the default setting will suffice.  
S1-6  
Reserved  
S1-7  
S1-8  
Reserved  
Reserved  
Off  
Off  
Switch S1-1: RDL Type  
SW1-4  
Off  
On  
Off  
On  
SW1-5  
Off  
Off  
On  
On  
Function  
-(0dB)  
-7.5dB  
-15.0dB  
-22.5dB  
Switch S1-1 selects the type of Remote Digital Loopback that the  
2720 will initiate when the RDL is initiated from this unit. The 2720 will  
respond to both the V54 and the CSU loopback regardless of the set-  
ting of S1-1  
S1-1  
On  
Off  
RDL Type  
Initiate a V.54 RDL loop when selected  
Initiate a CSU loopback when selected  
Switch S1-6 Through S1-8: Reserved  
Switch S1-2: Reserved  
11  
12  
 
4) When the unit is first turned on, the terminal screen may  
appear blank. Press the [Enter] key. If your serial connection  
is good, the unit will immediately display a password prompt.  
The following message will appear in the middle of the  
screen:  
3.2 SOFTWARE CONFIGURATION  
The Model 2720 features a menu-driven command system that  
allows you to monitor/configure its operating parameters. Follow the  
instructions below to configure the Model 2720 using the software  
selections:  
1) Plug the 9-pin male end of the cable to your terminal or com-  
puter’s DB-9 serial port and start up the terminal emulator  
software if necessary. Plug the miniature stereo plug into the  
rear of the unit. The small recessed jack on the left side of  
the unit is the control port jack.  
Patton Electronics  
Menu Management  
NOTE: If your terminal uses a DB-25 connector, please use a  
DB-9 to DB-25 Adapter to connect to the cable.  
Enter Password: _  
2) Power up the terminal and set its RS-232 port as follows:  
9600 Baud  
8 data bits, 1 stop bit, no parity  
Local echo off  
ANSI or VT-100 emulation  
5) Type in the password and press [Enter]. The factory default  
password for the unit is (password is case sensitive):  
3) Here is an example of a terminal emulator setup session. In  
normal font are the various parameter types. In bold type are  
the values that should be used for best results. Your terminal  
program’s setup screen may differ from this one:  
patton  
NOTE: If the entry is incorrect, the password screen will clear  
and prompt you again for the correct password. The password  
you enter will not be shown. For security, asterisks will be dis-  
played for each letter you type. The maximum length of the  
password, which can include any character the terminal can  
generate, is 16 characters.  
Baud rate: 9600  
Parity: None  
Data Length: 8  
Stop Bits: 1  
Default terminal type:  
Local Echo:  
VT100  
Off  
6) The Model 2720 will then display the Main Menu screen.  
Add Line Feeds after CRs:  
Received Backspace Destructive:  
Backspace key sends:  
Off  
On  
BS  
XON/XOFF software flow control:  
CTS/RTS hardware flow control:  
DSR/DTR hardware flow control:  
On  
Off  
Off  
13  
14  
 
3.2.1 Introduction to Main Menu  
The Main Menu options are briefly described below.  
a
After entering the password, you may access all of the system’s  
functions and parameters. The Main Menu looks like this:  
System Configuration options allow you to change various  
aspects of the Model 2720’s operation, e.g., framing, line cod-  
ing, and aggregate bandwidth.  
System Diagnostics/Statistics options allow you to monitor  
the network performance, initiate V.54 loops, local loops, and  
send test patterns. Network performance parameters are  
updated once a second, giving you the ability to quickly deter-  
mine if there is a problem.  
b
Unit Options allow you to customize the Model 2720 for your  
location. You can change the default header names to give  
each unit a unique name and password. Also, you can reset  
the unit to its default settings without the manual. It also has a  
Service Information screen in case you need technical assis-  
tance from Patton Electronics.  
c
Save Changes. Once you have configured the unit to your  
satisfaction, you can save the changes permanently by exe-  
cuting the Save Changes command. This will update the unit’s  
configuration and save all the parameters to permanent mem-  
ory.  
d
e
HELPFUL HINTS  
Logoff. For security, log off the control menu by executing  
the Logoff command. This will blank the screen until an  
[Enter] key is pressed.  
1. To make a selection, key the highlighted letter that corre-  
sponds to a menu selection.  
2. To execute the selection, type [Enter/CR]  
3. To toggle between options on a highlighted selection, Press  
[space].  
d
4. Select  
Save Changes from Main Menu after making modi-  
fications to any Model 2720 parameter. Otherwise, changes  
will be lost when the Model 2720 is turned off.  
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16  
 
3.2.2 System Configuration  
ESF: This stands for Extended Superframe Format, a line format  
developed by AT&T. AT&T Technical Reference 54016 (TR  
54016) defines the ESF, a format which is commonly used to  
allow monitoring of the network interface performance over  
the Facility Data Link (FDL). AT&T TR 62411 says, “the  
Extended Superframe Format “extends” the DS1 superframe  
structure from 12 to 24 frames…for a total of 4632 bits. It  
redefines the 8 kb/s channel previously used exclusively for  
terminal and robbed bit signaling synchronization.” The ESF  
provides a 4 kb/s data link, called the FDL, which allows for  
in-service monitoring and fast troubleshooting. Certain net-  
work services require the ESF.  
The default System Configuration menu looks like this:  
UNFRAMED:This is a special mode that allows you to achieve the  
maximum possible data rate of 1.544 Mb/s (million bits per  
second) by using the framing bits for data transmission. There  
is no signaling or FDL. This is commonly used for campus  
connections, and by the Federal government and the military.  
This format is not to be used when connecting to a public car-  
rier’s network without its permission. This provides one chan-  
nel at a rate of 1.544 Mb/s. In addition, this format can be  
used with external clocking.  
The System Configuration options are described below:  
b
Line Coding: B8ZS (default)  
Options: AMI, B8ZS, B7ZS.  
a
Line Format: ESF (default)  
AMI: Alternate Mark Inversion defines a pulse as a “mark”, a  
binary one, as opposed to a zero. In a T1 (DS1) network con-  
nection, signals are transmitted as a sequence of ones and  
zeros. Ones are sent as pulses, and zeros are sent as  
spaces, i.e., no pulse. Every other pulse is inverted from the  
previous pulse in polarity, so that the signal can be effectively  
transmitted. This means, however, that a long sequence of  
zeros in the data stream will cause problems, since the  
CSU/DSU receiving the signal relies on the signal to recover  
the 1.544 Mb/s clock. To get around this problem, one method  
is to limit the data rate per channel (known as a DS0,  
because it is a 64 kb/s portion of the DS1 frame or super-  
frame) to 56 kb/s and forcing a pulse in the last data bit to  
ensure a minimum pulse density in the signal. If you must use  
AMI with a DS0 data rate of 64 kb/s, you should ensure that  
the data terminal equipment connected to the unit provides a  
minimally acceptable pulse density. For this reason, there are  
advantages to using B8ZS instead.  
Options: ESF, D4, UNFRAMED  
D4: This is an older, but widely used, line format that does not  
provide FDL, so network interface performance cannot be  
monitored so easily. AT&T TR 62411 contains the specifica-  
tions for this format and the ESF. D4 is also known as  
Superframe format. According to TR 62411, “The Superframe  
format…consists of 12 frames of 193 bits each for a total of  
2316 bits. Each 193 bit frame consists of 192 bits preceded  
by one framing bit….the framing bit is time shared to both  
synchronize the terminal equipment and to identify the signal-  
ing frames.” (Sec. 4.1.1)  
17  
18  
 
d
Clocking: Network (default)  
B8ZS: Bipolar violations occur when consecutive pulses are of  
the same polarity. In B8ZS, or Bipolar Eight Zero Substitution,  
bipolar violations are introduced deliberately to indicate that  
eight zeros have been transmitted. This special encoding is  
recognized by the receiver and decoded correctly. See AT&T  
TR62411 Section 4.2.2 for a detailed description of B8ZS.  
This enables information to be sent over a T1 connection  
without any constraints on the data’s pulse density. This is the  
most acceptable way to accomplish 64 kb/s on each DS0  
channel.  
Options:  
Network, Internal, External  
Network: This is the most commonly used setting when connect  
ing to a carrier’s network. In this mode, the unit recovers the  
clock from the received signal and uses it to transmit data. In  
this way the unit remains synchronized to a master clock. In  
campus applications, one of the units must be set to Internal  
clock, and the other end is set to Network clock. At all times,  
there must be only one clock source. Otherwise, clock slips  
and framing errors and bit errors may occur.  
B7ZS: This stands for Bipolar Seven Zero Substitution. Instead of  
introducing bipolar violations, this method substitutes a one  
for a zero in bit 7 (out of 8) of a DS0 channel when the data in  
that channel are all zeros. This is a special form of AMI and is  
compatible only with special equipment. For most applica-  
tions, AMI or B8ZS will suffice.  
Internal: This is commonly used in campus applications, where  
the unit is not connected to the public telephone network  
directly. In this mode, the unit uses the on-board oscillator as  
the transmit clock source.  
External: This is a special mode that should only be used with  
the Unframed format. In this mode, the unit requires a 1.544  
Mhz clock signal from the DTE via the external clock pin on  
the DTE interface connector. Most applications will use  
Network or Internal clock modes.  
DS0 Line Rate: 64kbps (default)  
c
Options: 64kbps, 56kbps  
64kbps: Also known as Clear Channel, this takes full advantage  
of the available bandwidth in a DS0 channel. Implementing it  
usually requires B8ZS line coding. In certain cases, special  
equipment may implement Clear Channel using AMI or B7ZS.  
Consult the equipment manual for compatibility. Your carrier  
will advise you on whether to use 64 or 56 kb/s. Campus  
applications may not have such restrictions, enabling you to  
use 64kbps. In Unframed format, the 24 DS0s and the fram-  
ing bits are combined to provide 1.544Mb/s for your use.  
e
Line Build Out (dB): 0 – 133 feet, 0 dB (default)  
Options:  
0 – 133 feet, 0 dB  
133 – 266 feet  
266 – 399 feet  
399 – 533 feet  
533 - 655 feet  
-7.5 dB  
-15.0 dB  
-22.5 dB  
56kbps: This uses only the first seven bits of the DS0, limiting the  
data rate per DS0 channel to 56 kb/s. Your carrier will advise  
you on whether to use 64 or 56 kb/s. This is not available  
when using the Unframed format.  
This controls the transmitter signal strength and pulse shape. For  
most applications, the default setting will suffice. When connecting to a  
carrier connection, the carrier will determine what LBO is necessary. 0  
dB provides the highest signal strength and therefore the longest dis-  
tance, while –15.0 dB provides the lowest usable signal strength. The  
last setting, –22.5 dB, is usually only used to test the line and should  
not be used in normal applications.  
19  
20  
 
ESF Data Link: ANSI T1.403 (default)  
Remote In-band Loops: Enabled (default)  
Options: Enabled, Disabled  
f
h
Options: ANSI T1.403, AT&T TR54016  
ANSI T1.403: This ANSI developed standard (see ANSI T1.403-  
1995: Network-to-Customer Installation—DS1 Metallic  
Interface) uses the FDL to send and receive one second  
Performance Report Messages (PRMs). The messages con-  
tain the NI performance over the last four seconds. Thus, up  
to three consecutive messages may be lost without loss of  
information. It is available only with ESF. When ANSI T1.403  
is selected, requests to send AT&T performance reports (ref.  
AT&T TR 54016) are ignored.  
In ESF, D4 and Unframed formats, the unit can respond to special  
repeating codes in the data stream that represent loopback com-  
mands. The command to loop up (go into loopback) is a repeating pat-  
tern of 00001s. This pattern overwrites the normal data. When this  
code is detected for 5 seconds, the unit will go into loopback if the  
Remote In-band Loopback is Enabled. When a repeating code of 001s  
is received for 5 seconds, the unit loops down (goes out of loopback).  
The delayed recognition guards against false starts, since the code  
must be present for a long time continuously. When Disabled, the unit  
will recognize the codes but will not respond to them. The loopback  
timeout also applies to this feature.  
AT&T TR54016: Developed by AT&T, this FDL method differs  
principally from the ANSI method in two ways: First, the ANSI  
method transmits messages continuously, whereas the AT&T  
method transmits a performance report only upon a request  
from the remote end for a report. Second, the AT&T method  
provides a historical summary, up to the last 24 hours, of NI  
performance. Only the service provider or special test equip-  
ment can send these requests. When AT&T TR54016 is  
selected, ANSI PRMs are still transmitted by the unit, but only  
PRMs sent by the carrier will be recognized. To receive PRMs  
from another customer unit (i.e., in a campus application),  
select ANSI T1.403. When the frame is not ESF, the FDL is  
disabled.  
i
V.54 Loops (RDL Only): Enabled (default)  
Options: Enabled, Disabled  
This is a special in-band loopback facility that sends a special  
pseudo-random pattern over the data stream. This is the only remote  
loopback that the unit can initiate. This is useful for campus applica-  
tions when you need to put a remote unit in loopback. The remote unit  
responds to the V.54 loopback command, and the whole process takes  
only a few seconds to complete. This setting will enable/disable RDL  
from being initiated from either the control port or the DTE interface. It  
will also enable/disable the unit to respond to the V.54 command if  
received over the line. The duration of the loopback is limited by the  
loopback timeout setting. (See Unit Operations, paragraph 3.2.4, on  
pages 32 and 33.)  
ESF Carrier Loops: Enabled (default)  
g
Options: Enabled, Disabled  
The ESF format provides the CO the ability to put the customer  
j
installation’s Model 2720 into loopback mode. The Model 2720 recog-  
nizes these special messages that are sent over the FDL. When  
enabled, the unit will respond to these loopback commands and go into  
or out of loopback mode. When disabled, the unit will not respond,  
although it still recognizes the loopback commands. When in loopback,  
the unit will remain in loopback until a loopback exit command is  
received or when the loopback timer times out. See Unit Options  
(Section 3.2.4) to make Loop Timeout choices. This feature allows the  
remote user to regain control should one be locked out after a loop-  
back is initiated.  
Default Config Source: Switch (default)  
Option: EEPROM, Switch  
The Model 2720 can be initialized via the configuration in the on-  
board permanent memory (EEPROM) or via the internal DIP switches  
(Switch). Once the unit is powered up, you may change the settings  
through the control port or the DIP switches.  
If you do not have a terminal, you may force the unit to use the  
DIP switches as the default configuration source by turning off the unit,  
setting all the DIP switches to the ON position, then powering on the  
22  
21  
 
unit. This will cause the unit to enter a special mode. Then turn off the  
unit and change the switch settings to the desired settings. When you  
turn the unit on again, the unit will be set up with the selected switch  
settings.  
3.2.3 System Diagnostics  
The System Diagnostics/Statistics screen looks like this:  
DS0 Channel Configuration Menu: [ Bandwidth/# Channels =  
1,536/24 ] (default)  
n
The DS0 Channel Configuration Menu has a sub-menu that looks  
like this:  
NOTE: This screen is updated once per second.  
The System Diagnostics/Statistics options and functions are  
described below.  
a
Local Loop: Idle (default)  
The Local Loop is a bi-lateral loopback in which the data from the  
You may configure the Model 2720 to operate with any combina-  
local DTE and the data from the remote unit are looped back to their  
respective sources (See Section 5.3). Activate this loop to test the  
each of the DTE’s connection to the Model 2720.  
tion of active and inactive DS0 channels in this screen. When you exe-  
cute the Save Changes command, the selected settings will be saved  
to permanent memory, and the system will be updated to operate with  
the new channel settings.  
The Local Loop test has four states:  
NOTE: In Unframed format, the Bandwidth Selected will display  
“1,544k,” and the Total Channels will display “n/a.” When the DS0  
Channel Rate is 56kbps, the Bandwidth Selected will be a multiple  
of 56k, not of 64k. When using the DIP switches to set the band-  
width, the starting channel is always channel 1.  
Idle  
LL  
No user-controlled loopbacks are active.  
The Model 2720 is in local loopback mode.  
Off  
The Model 2720 is in remote or CO initiated loopback  
mode or sending a pattern. Local loopback is disabled.  
LocP  
The Model 2720 is in Local Loopback mode, and is send-  
ing a test pattern.  
23  
24  
 
Remote Loop Idle (default)  
The Model 2720 receiving a RL can be in one of the following states:  
b
The Remote Digital Loopback (RDL) test checks the performance  
RxPr  
Sack  
The Model 2720 is receiving a preparatory pattern.  
of both the local and remote Model 2720s, as well as the communica-  
tion link between them. Data from the local DTE is sent across the  
entire communication circuit and looped back to the local DTE.  
The Model 2720, upon receiving a preparatory pattern,  
sends an acknowledgement message.  
The Model 2720 Initiating a RL can be in one of the following  
states:  
RL  
The Model 2720 is in remote loopback mode.  
RxTr  
The Model 2720 is receiving a terminate loopback mes-  
sage.  
Idle  
No user-controlled loopbacks are active.  
TxPr  
The Model 2720 is sending the preparatory phase pattern  
lasting for approximately 2 -5 seconds.  
Wt1s  
The Model 2720 is waiting for a sequence of all ones and  
will time out if it does not receive it.  
WtAk The Model 2720 is waiting for an acknowledgement from  
the remote unit. If the remote unit does not respond, the  
WtAk message will remain on the screen.  
IdleP  
Off  
The Model 2720 is sending a QRSS, 511 or 2047 pattern.  
The Model 2720 is in local loopback.  
RxAk The Model 2720 has received an acknowledgement from  
the remote unit.  
Test Pattern Idle (default)  
c
Tout  
TM  
The Model 2720 is waiting before entering the Remote  
Loopback test mode.  
Options: Idle or Sending  
To send a pattern, press the ‘c’ key and press <spacebar> to send  
The Model 2720 has successfully negotiated the Remote  
Loopback test and is in control of the remote unit. You  
may send a test pattern at this point by pressing:  
the test pattern. The “OK” message indicates the received test pattern  
is error-free. The “BE” message indicates errors in the received pat-  
tern.  
c <spacebar>  
Idle  
Indicates that Model 2720 is not sending a pattern.  
TxTr  
Tx1s  
The Model 2720 is sending a Terminate Loopback mes-  
sage to the remote unit. If the remote unit does not  
respond, the local unit will return to the Idle state.  
Sending Indicates that 2720 is sending a pattern.  
Error Insertion Off (default)  
d
If the remote Model 2720 responds to the local NetLink-  
T1™’s terminate loopback request, the local unit then  
sends an all ones pattern before returning to the Idle  
state  
Options: On, Off  
You may inject intentional errors into the test pattern by turning  
Error Insertion ON. The Error (ERR) LED will blink once per second.  
TxP  
IdlP  
The Model 2720 is sending a test pattern while in Test  
Mode  
Selected Pattern  
e
Options: QRSS, 511, or 2047  
The Model 2720 is sending a test pattern in place of data.  
The Model 2720 is not in test mode.  
Use this option to select the test pattern used to test the link.  
25  
26  
 
NI STATUS  
Receive Alarm Indication [RAI] indicates that the local unit is receiv-  
ing a Yellow Alarm. This alarm is sent by the remote unit or the central  
office when it loses the received signal. This indicates the local unit’s  
transmitted signal is not reaching the remote unit.  
The Network interface (NI) status is shown in  
the middle of the Diagnostics/Statistics screen.  
The brackets are empty when the link is operat-  
ing normally. In this example, various two or  
three-letter messages are displayed within the  
brackets, illustrating what you may see if the  
Model 2720 is not connected at all or is in a loss  
of signal condition. Here are the eight status mes-  
sages.  
Rx Level The Model 2720 displays the current received signal  
strength in dB. There are four level ranges detected:  
+2 to –7.5  
-7.5 to –15  
-15 to –22.5  
< -22.5  
Excessive zeros [EXZ], i.e., lack of pulses, detected. This condition  
may occur if the unit is not connected to the network, in which case the  
EXZ is displayed continuously. If EXZ comes on intermittently, there  
may be a frame, line code or data rate mismatch between the near and  
far-end units.  
Valid Interval Count & Current Interval Time  
The Valid Interval Count and Current Interval Time display the  
number of valid 15 minute intervals in the last 24 hours and the num-  
ber of seconds which have elapsed in the current interval, respectively.  
The Valid Interval Count saturates at the count of 96 (96 * 15min = 24  
hours), while the Current Interval Time rolls over after 900 counts.  
When the counter rolls over, it is reset to zero, and the Interval Counter  
is incremented by one if the count is less than 96.  
Receiver Carrier Loss [RCL] occurs when 192 consecutive zeros  
have been detected at the network interface. RCL clears when a pulse  
is detected.  
Frame Bit Error [FE] occurs when there is an error in the framing bit  
sequence. This may happen due to a disconnected line, mismatched  
framing formats or severe errors in the data stream. This error may  
indicate a noisy line or cable condition. This error may indicate a noisy  
line or cable connection if the frames appear to be set correctly.  
Valid Interval Count: [96]  
Current Interval Time: [899]  
Error Counters  
Severe Frame Error [SE] occurs when the framing error exceeds a  
certain threshold of errors. This may happen due to a disconnected  
line, an extremely noisy connection, or mismatched framing.  
These error counters give a second-by-second snapshot of the  
link performance. To clear all counters, press the [Backspace] key. If  
your keyboard does not have this key, you can press a two-key combi-  
nation to affect the same result: Hold down the [Ctrl] key and then  
press the [H] key. This will send to the unit the Ctrl-H character, which  
is the same as pressing the [Backspace] key.  
Loss of Sync [LOS] occurs when the T1 framer in the unit cannot  
synchronize itself to the received data stream. This may happen due to  
a disconnected line.  
ERR SEC:  
UAS SEC:  
SE SEC:  
0
557  
0
0
209  
0
Errored Seconds in Current Interval....  
Unavailable Seconds  
Severely Errored Seconds  
Bursty Errored Seconds  
Out of Frame [OOF] occurs when no valid frame structure can be  
found. This may happen due to a disconnected line or mismatched  
framing or mismatched framing.  
BE SEC:  
0
0
LOF SEC:  
0
0
Loss of Frame Error Seconds  
Alarm Indication Signal [AIS] indicates that the remote unit or the  
central office is sending a Blue Alarm, because it is not receiving a sig-  
nal; the alarm is an unframed all-ones signal, mainly used to keep the  
line alive and to indicate that it is not receiving any signal. This may  
indicate that the local unit is receiving a good signal, but that the trans-  
mit link may be broken.  
28  
27  
 
Rx PRM  
The NetLink-T1™ transmits ANSI performance report messages  
3.3.6 Unit Information  
The Unit Options screen looks like this (factory default):  
once a second when the framing mode is ESF. When the ESF Data  
Link is set to ANSI T1.403, the unit recognizes PRMs with addresses  
of 38h or 3Ah. The address 3Ah indicates the PRM is coming from a  
Carrier, whereas the address 38h indicates the PRM is coming from a  
Customer. When the ESF Data Link is set to AT&T TR54016, the unit  
recognizes Carrier-originated PRMs, which have an address of 3Ah.  
Rx PRM: 00010000000300023289  
Current DIP Switch Settings  
The Switch settings are displayed here to  
facilitate troubleshooting your unit without  
opening up the unit first.  
Header Line 1 & Header Line 2  
Headers 1 and 2 are provided for easy identification of your unit  
after installation. You may want to give each unit a unique name via  
the header lines to help distinguish one unit from another. You can  
enter a header up to 40 letters long. Two lines provide 80 letters for  
your use. That’s a lot of flexibility!  
Password  
The Password facility provides security by allowing only those who  
know the correct password to configure the unit via the control port.  
You can still configure the unit via the DIP switches. The password can  
be up to 16 characters long, with no restriction on the combination of  
characters you can use, so be sure to remember the password. If you  
lose your password, you will lose the ability to access the unit via the  
control port.  
29  
30  
 
4.0 INSTALLATION  
Loop Timeout  
The Loop Timeout setting can be set to one of the following:  
The Model 2720 is equipped with DTE, network, and power inter-  
faces. This section briefly describes connection to each.  
00:05 =  
00:10 =  
00:15 =  
00:30 =  
00:45 =  
01:00 =  
01:30 =  
02:00 =  
03:00 =  
NEVER =  
five minutes  
ten minutes  
fifteen minutes  
thirty minutes (default setting)  
forty-five minutes  
one hour  
90 minutes  
two hours  
4.1 DTE INTERFACE CONNECTION  
The DTE interface is a V.35 DCE presented as an M/34 male con-  
nector. This interface is designed to plug directly into a DTE interface  
(See Appendix D for V.35 interface pin assignments).  
4.2 NETWORK INTERFACE CONNECTION  
three hours  
forever—the unit will remain in loopback without user  
intervention.  
The Network Line Interface is an eight position keyed modular jack  
configured as a RJ-48C. This interface will need to be configured to  
match the line parameters (i.e. framing, line coding, etc.) supplied by  
the central office.  
Tx Data Clock  
1 RX Data (TIP)  
1
}
}
From Network  
To network  
2 RX Data (RING)  
3 (no connection)  
4 TX Data (TIP)  
5 TX Data (RING)  
6 (no connection)  
7 (no connection)  
8 (no connection)  
This option selects the clock that is used to accept the Transmit  
Data from the DTE interface. Standard DTE interfaces will transmit  
data with respect to the External Clock. In some cases a DTE interface  
will transmit with respect to the Transmit clock sent out from the 2720.  
Please review the information provided with your DTE equipment for  
more information on its' operation. In most cases when there are errors  
on the line only in the direction of the transmit data either Tx Data  
Clock or Tx Clock Invert can be changed to solve the problem.  
2
3
4
5
6
7
8
Figure 2. Model 2720 twisted pair line interface.  
Tx Clock Invert  
NOTE:  
If the Model 2720 is being used for private short range  
modem applications, the twisted pair cable connected to  
its port will need to be a crossover cable. See Appendix  
D for Interface pin assignments.  
This option allows the user to invert the transmit clock originating  
in the 2720. When Tx Data Clock is set for transmit clock, it may be  
necessary to invert the transmit clock to allow for cable delays.  
4.3 DC POWER SUPPLY  
Set to Default Configuration  
The 36-60 VDC DC to DC adapter is supplied with the DC version of  
the Model 2720. The black and red leads plug into a DC source (nomi-  
nal 48VDC) and the barrel power connector plugs into the barrel power  
supply jack on the 2720.  
You may set the NetLink-T1™ to its factory default configuration,  
except for the header lines and the password, by executing the Set to  
Default Configuration command.  
To Power  
To -48VDC  
Supply Jack  
Source  
-Vin  
Black lead (-V)  
Red lead (+V)  
+Vin  
Barrel power connector  
31  
32  
 
5.0 OPERATION  
Once the NetLink-T1™ is installed and configured properly it is  
ready to place into operation. This section describes the function of  
the LED indicators, and the use of the loopback and pattern test  
modes.  
ER  
The error LED indicates various error condi-  
tions, including framing bit errors, excessive  
zeros, controlled slips, severe errors, or bit  
errors (when sending V.52 test patterns).  
When sending a test pattern, the LED will  
remain lit if the unit does not receive the  
identical pattern. When it receives the cor-  
rect pattern, the LED will turn off. If error  
insertion is on, the LED will blink once a  
second if everything is operating properly.  
5.1 LED DESCRIPTIONS  
The NetLink-T1™ is equipped with six LED indicators that monitor  
the status of communication. Figure 12 (below) shows the location of  
the LEDs on the NetLink-T1™ Series front panel.  
TM  
The test indicator LED blinks with a specific  
pattern depending on the type of test mode.  
When the unit is in local analog loop, the  
LED will blink on briefly. When the unit is in  
remote loop, the TM LED will blink off  
briefly. When the unit is sending a test pat-  
tern or is putting the remote unit into  
V.54/CSU loopback, the TM LED will stay  
on. These are the test modes:  
Figure 3: 2720/C Front Panel  
T1 Link  
TD  
Solid green indicates that the end to end TI  
link is up. Signifying that the link is active.  
The TI link LED is off when the link is down  
V.54/CSU Loopback & V.52 Patterns  
• D4 Line Loop (CO initiated)  
• ESF Line Loop (CO Initiated)  
• ESF Payload Loop (CO Initiated)  
When the unit sends a one, the TD LED is  
green. When it sends a zero, the TD LED is  
orange. Moreover, the TD LED is active  
only in active DS0 channels. In inactive  
channels, the TD LED is off.  
RD  
When the unit receives a one, the RD LED  
is green. When it receives a zero, the RD  
LED is orange. Moreover, the RD LED is  
active only in active DS0 channels. In inac-  
tive channels, the RD LED is off.  
ALM  
The alarm LED indicates the presence of a  
Blue or Yellow Alarm, or Out of Frame con-  
dition. The ALM LED will blink on every half-  
second. Alarms may occur due to:  
Loss of Synchronization  
• Loss of Frame  
• AIS (Blue Alarm)  
• RAI (Yellow Alarm)  
33  
34  
 
To perform an RDL test, follow these steps:  
5.2 LOOP (V.54 & TELCO) DIAGNOSTICS  
1. Activate RDL. This may be done in three ways:  
The NetLink-T1™ offers three V.54 loop diagnostics and is com-  
patible with two Telco loop diagnostics. Use these diagnostics to test  
the CSU/DSU and any communication links. These tests can be acti-  
vated via the software control port (See Section 3.2.3 System  
Diagnostics), via signals on the serial port interface or the front panel  
switch.  
b
a. Enter  
Diagnostics/Statistics menu and toggle the <Spacebar>  
until “RL” appears next to the Remote Loop option.;  
Remote Loop from the System  
b
b. Activate the “RL” signal on the DTE. If you are not sure  
which lead is the “RL” signal, please refer to Appendix D.  
5.2.1 Operating Local Loopback (LL)  
c. Set the front panel switch to ‘Remote’.  
The Local Loopback (LL) test checks the operation of the local  
NetLink-T1™, and is performed separately on each unit. Any data sent  
to the local NetLink-T1™ in this test mode will be echoed (returned)  
back to the user device (i.e., characters typed on the keyboard of a ter-  
minal will appear on the terminal screen).  
2. Perform a bit error rate test (BERT) using the internal V.52  
generator (as described in Section 5.3), or using a separate  
BER Tester. If the BER test indicates a fault, and the Local  
Line Loopback test was successful for both NetLink™s, you  
may have a problem with the twisted pair line connection.  
To perform a LL test, follow these steps:  
5.2.3 CSU Loop  
1. Activate LL. This may be done in one of three ways:  
The NetLink-T1™ also responds to central office initiated loop com-  
mands. The NetLink-T1™ will implement the “loop up” command when  
it recognizes the pattern “10000” in the data stream for a minimum of 5  
seconds. The “loop down” command is implemented by the pattern  
“100” in the data stream for a minimum of 5 seconds.  
a
a. Enter  
Diagnostics/Statistics menu and toggle the <Spacebar>  
until “LL” appears next to the Local Loop option.  
Local Loop from the System  
a
b. Activate the “LL” signal on the DTE. If you are not sure  
which lead is the “LL” signal, please refer to Appendix D.  
When operating in ESF framing mode, loopback commands are  
issued via the Facility Data Link (FDL). The line loop message will  
cause a loop back before data enters the framer portion of the CSU.  
The payload loop message will cause the NetLink-T1™ to loop data  
after the framer portion of the CSU.  
c. Toggle the front panel switch to the “Local” position.  
2. Verify that the data terminal equipment is operating properly  
and can be used for a test.  
The NetLink-T1™ will respond to Universal Loopback De-activate  
to clear all central office loops.  
3. Perform a V.52 BER (bit error rate) test as described in  
Section 5.3. If the BER test equipment indicates no faults,  
but the data terminal indicates a fault, follow the manufactur-  
er’s checkout procedures for the data terminal. Also, check  
the interface cable between the terminal and the NetLink-T1.  
5.2.2 Operating Remote Digital Loopback (RL)  
The Remote Digital Loopback (RL) test checks the performance of  
both the local and remote NetLink-T1™, as well as the communication  
link between them. Any characters sent to the remote NetLink-T1™ in  
this test mode will be returned back to the originating device (i.e, char-  
acters typed on the keyboard of the local terminal will appear on the  
local terminal screen after having been passed to the remote NetLink-  
T1™ and looped back).  
35  
36  
 
5.3 BIT ERROR RATE (V.52) DIAGNOSTICS  
APPENDIX A  
PATTON NETLINK-T1 MODEL 2720  
SPECIFICATIONS  
The NetLink-T1™ offers three V.52 Bit Error Rate (BER) test pat-  
terns. These test patterns may be invoked along with the LAL and  
RDL tests to evaluate the unit(s) and the communication links.  
WAN Speed:  
1.544 Mbps  
When a 511, 2047, or QRSS test is invoked, the NetLink-T1™  
generates a pseudo-random bit pattern of 511 bits, 2047 bits or 220  
bits, respectively, using a mathematical polynomial. The receiving  
NetLink- T1™ then decodes the received bits using the same polyno-  
mial. If the received bits match the agreed upon pseudo-random pat-  
tern, then the NetLink-T1™(s) and the communication link(s) are func-  
tioning properly.  
WAN Connection:  
Nominal Impedance:  
DTE Interface:  
Line Coding:  
RJ-48C  
100 Ohms  
EIA-530, ITU/T V.35, M/34 female, or  
EIA-530, DB25 female  
AMI/B8ZS  
511  
Initiates a built-in 511 bit pseudo-random  
pattern generator and detector.  
Line Framing  
D4/ESF/Unframed  
Automatic  
2047  
QRSS  
Initiates a built-in 2047 bit pseudo-random  
pattern generator and detector.  
Receive LBO:  
Initiates a built-in 220 bit pseudo-random  
pattern generator and detector.  
Transmit LBO:  
Selectable - 0, 7.5,  
15, or 22.5 dB, plus DSX-1  
Clock Options:  
Diagnostics:  
Internal, external or network clock  
To perform a V.52 test, follow these steps:  
Responds to CO-initiated D4 loopup  
and loopdown codes, ESF line loop  
and payload loop FDL messages,  
Universal Loopback De-activate mes-  
sage  
1. Activate the local loopback or remote loopback diagnostic.  
2. Activate the test pattern. This may be done in one of two  
ways:  
Standards:  
AT&T TR62411, TR54016, ANSI T1.403  
e
a. Enter  
Selected Pattern from the System  
Diagnostics/Statistics menu and toggle the <Spacebar>  
until the desired test pattern appears.  
Power Supply:  
120VAC, 60 Hz to 5VDC 300mA wall-  
mount transformer or UI 100-240VAC,  
50-60 Hz to 5 VDC, 2A desktop trans-  
former  
c
b. Enter  
Test Pattern and toggle the [Spacebar] to send  
the selected pattern.  
Dimensions:  
3.5”L x 2.1”W x 0.78”H (9.0 x 5.3 x 1.9  
cm)  
5.0’’ L x 42’’ W x 1.5’’ H  
c. One of two result codes will appear to the right of the  
Test Pattern listing:  
c
OK Indicates that the received test pattern is error-free.  
BE Indicates that there are errors in the test pattern (to  
deliberately insert errors in the pattern, toggle  
Error Insertion to ON).  
d
37  
38  
 
APPENDIX B  
APPENDIX C  
PATTON NETLINK-T1™ MODEL 2720  
CABLE RECOMMENDATIONS  
PATTON NETLINK-T1™ MODEL 2720  
FACTORY REPLACEMENT PARTS  
AND ACCESSORIES  
Patton Model #  
Description  
10 - 09F............................6 Foot Control Port Cable, 25mm to  
DB9F  
The Patton Model 2720 Series has been performance tested by  
Patton technicians using twisted-pair cable with the following charac-  
teristics:  
07M2720..........................User Manual  
2720/C/VI.........................T1 N x 64 CSU/DSU(M/34 female, UI)  
2720/B/VI.........................T1 N x 64 CSU/DSU(DB25 female,UI)  
2720/I/VI..........................T1 N x 64CSU/DSU(10BaseTEthernet,VI)  
Wire Gauge  
Capacitance  
Resistance  
19 AWG  
22 AWG  
24 AWG  
83nf/mi or 15.72 pf/ft.  
83nf/mi or 15.72 pf/ft.  
83nf/mi or 15.72 pf/ft.  
.0163 Ohms/ft.  
.0326 Ohms/ft.  
.05165 Ohms/ft.  
To gain optimum performance from the Model 2720 Series, please  
keep the following guidelines in mind:  
Always use twisted pair wire—this is not an option.  
• Use twisted pair wire with a capacitance of 20pf/ft or less.  
• Avoid twisted pair wire thinner than 26 AWG (i.e. avoid AWG  
numbers higher than 26)  
• Use of twisted pair with a resistance greater than the above  
specifications may cause a reduction in maximum distance obtain-  
able. Functionality should not be affected.  
• Many environmental factors can affect the maximum distance  
obtainable at a particular site.  
39  
40  
 
APPENDIX D  
APPENDIX D (continued)  
PATTON NETLINK-T1™ MODEL 2720  
INTERFACE PIN ASSIGNMENT  
PATTON ELECTRONICS MODEL 2720  
INTERFACE PIN ASSIGNMENT  
M/34 Connector, Terminal Interface  
RJ-48C T1 (DS0) Network Interface  
(Female Modular Jack)  
Pin #  
A
Signal  
GND (Earth Ground/Shield)  
Pin #  
Signal  
B
SGND (Signal Ground)  
1
2
4
5
RX Data (TIP 1)  
RX Data (RING1)  
TX Data (TIP)  
TX Data (RING)  
D
CTS (DCE Source)  
E
DSR (DCE Source, Always On)  
CD (DCE Source)  
F
L
LL (Local Loop, DTE Source)  
TM (Test Mode Indicator, DCE Source)  
RL (Remote Loop, DTE Source)  
TD (Transmit Data +, DTE Source)  
RD (Receive Data +, DCE Source)  
TD/ (Transmit Data -, DTE Source)  
RD/ (Receive Data -, DCE Source)  
XTC (Transmit Clock +, DTE Source)  
RC (Receiver Clock +, DCE Source)  
XTC/ (Transmit Clock -, DCE Source)  
RC/ (Receiver Clock -, DCE Source)  
TC (Transmitter Clock +, DTE Source)  
TC/ (Transmitter Clock -, DTE Source)  
Aux. Power Input (+5VDC @ 300mA)  
TRS Jack (RS-232 Control Port)  
M
N
Pin #  
Signal Source  
From Model 2720  
To Model 2720  
N/A  
Tx Data  
Rx Data  
Sleeve  
P
R
S
T
RS-232 Control Port (Signals at DB-25 Connector)  
U
Pin#  
Signal  
Receive  
Transmit Data  
Ground  
Signal Direction  
From 2720  
To 2720  
V
3
2
7
W
X
Y
RS-232 Control Port (Signals at DB-9 Connecter)  
AA  
KK  
Pin#  
Signal  
Receive  
Transmit Data  
Ground  
Signal Direction  
From 2720  
To 2720  
3
2
7
41  
42  
 
APPENDIX E  
APPENDIX E  
PATTON NETLINK-T1™ MODEL 2720  
EIA-530 INTERFACE PIN ASSIGNMENT  
DB-25 Female Connector, Terminal Interface  
(continued)  
PATTON ELECTRONICS MODEL 2720  
INTERFACE PIN ASSIGNMENT  
X.21 Interface  
(DB-15 Female Connector)  
(DTE /DCE Configuration)  
Pin #  
1
Signal  
FG (FrameGround)  
2
TD (Transmit Data-A, DTE Source)  
RD (Receive Data-A, DCE Source)  
RTS (Request to Send-A, DTE Source)  
CTS (Clear to Send-A, DCE Source)  
DSR (Data Set Ready-A, DCE Source)  
SGND (Signal Ground)  
Pin #  
Signal  
3
1. . . . . . . . . . . . Frame Ground  
2. . . . . . . . . . . . T (Transmit Data-A)  
3. . . . . . . . . . . . C (Control-A)  
4. . . . . . . . . . . . R (Receive Data-A)  
5. . . . . . . . . . . . I (Indication-A)  
4
5
6
7
6. . . . . . . . . . . . S (Signal Element Timing-A)  
7 . . . . . . . . . . . BT (Byte Timing-A)  
8 . . . . . . . . . . . SGND (Signal Ground)  
9 . . . . . . . . . . . T/ (Transmit Data-B)  
10 . . . . . . . . . . . C/ (Control-B)  
11 . . . . . . . . . . . R/ (Receive Data-B)  
12 . . . . . . . . . . . I/ (Indication-B)  
13........................S/ (Signal Element Timing-B)  
8
CD (Carrier Detect-A, DCE Source)  
RC/ (Receiver Clock-B, DCE Source)  
CD/ (Carrier Detect-B, DCE Source)  
XTC/(External Transmitter Clock-B, DTE Source)  
TC/(Transmitter Clock-B, DTE Source)  
CTS/(Clear to Send-B, DCE Source)  
TD/(Transmit Data-A, DTE Source)  
TC(Transmitter Clock-B, DCE Source)  
RD (Receive Data-A, DCE Source)  
RC (Receiver Clock-A, DCE Source)  
LL (Local LIne Loop)  
9
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
22  
23  
24  
25  
14 .......................BT/ (Byte Timing-B)  
RTS/(Request to Send-B, DTE Source)  
DTR (Data Terminal Ready-A, DTE Source)  
DSR/ (Data Set Ready-B, DCE Source)  
DTR/(Data Terminal Ready-B, DTE Source)  
XTC (External Transmitter Clock-A, DTE Source)  
TM (Test Mode)  
44  
43  
 

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