User Manual

Looping back T1/E1 backhaul links
IP-RN 8000 Installation & Commissioning Guide 161
Looping back T1/E1 backhaul links
This section explains options for installing physical loopbacks when T1 or E1 backhaul link(s) are deployed
at the cell site. Because Airvana does not specify the external T1/E1 equipment used at cell sites, some
details of looping back the T1/E1 cables are site-dependent. Depending on the equipment deployed at the
site at the time of loopback testing, the location of the installed physical loopback will vary. (See also
Understanding backhaul loopback testing
on page 159.) The technique used to create the loopback will also
vary depending on installed third-party equipment.
1. If the backhaul cables that exit the cabinet are connected to a DSX (or an equivalent type of equipment),
the physical loopback should be installed on the IP-RN 8000 side of the DSX (or equivalent of
equipment). Use methods and materials to install the loopback that are appropriate to the third-party
equipment.
2. If the T1/ E1 backhaul cables exiting the cabinet hang free at the far end, build a physical loopback
appropriate to the cable type and install it at the far end of the cable.
This procedure is complete. Go to Entering diagnostic mode and configuring test parameters
on page 163.
NOTE
• Physical loopbacks are created by physically
connecting the positive transmit wire to the positive
receive wire and connecting the negative transmit
wire to the negative receive wire.
• Loopbacks must be installed on each and every T1/
E1 backhaul cable.
NOTE
Maximum cable lengths must be considered when installing
loopbacks. Loopbacks double the length of a cable (the outgoing
leg along the cable and the return leg). Failure to consider this
factor can result in failed loopback tests for cables that are
flawless.
DSX
TX positive
TX negative
RX positive
RX negative
IP-RN 8000 side
Carrier side
Install physical loopbacks
Cross connects
A T1/E1