Specifications

90 AR Router
C613-03058-00 REV A
Loopback Plugs for Testing Interfaces
Loopback plugs are used in conjunction with the Test Facility software (see the
Test Facility chapter) to test the router’s physical interfaces. The purpose of a
loopback plug is to connect the output pins on the interface to the input pins so
that any data transmitted over the interface is looped back (hence loopback
plug) and received at the same interface.
On interfaces with control signals, these are also looped back. The data
received on the interface is compared with the data transmitted to determine
whether or not the interface is functioning correctly. In order to produce a
comprehensive test report, most tests performed by the Test Facility require a
loopback plug to be inserted in the interface being tested.
Some interfaces (e.g., the synchronous ports) require a specially built external
testing device (available from your authorised Allied Telesyn distributor or
reseller) to be used in conjunction with the Test Facility.
Table 38 on page 90 lists the loopback plug wiring diagrams for each interface
type.
Figure53: RJ-45 loopback plug for testing asynchronous interfaces.
Table 38: Loopback plug pin wiring diagrams.
Physical Interface Loopback Method/Pin Wiring Diagram
RJ-45 asynchronous interface Figure 53 on page 90
DB9 Male Figure 54 on page 91
DB9 Female Figure 55 on page 91
Ethernet AUI interface Figure 56 on page 91
Ethernet TP interface Figure 57 on page 92
Basic Rate ISDN interface Figure 60 on page 93. Most BRI interfaces are
tested without a loopback plug. See “Loopback
Plugs for BRI Interfaces” on page 92 for
instructions on how to determine if a loopback
plug is required.
Primary Rate 75Ω interface Use a length of terminated cable as a loopback
cable on the interface.
Primary Rate 120Ω interface Figure 58 on page 92
RJ45 Asynchronous Port Loopback Plug (RJ45 connector)
1
2
3
4
5
6
7
8
(RING)
(DCD)
(DTR)
(GND)
(RXD)
(TXD)
(CTS)
(RTS)
12345678
Router end view
of plug
RJ45LOOP