Loopback Tests; Table 29-4 System Loopback Tests - Cisco BPX-BXM-155-8DX Installation And Configuration Manual

Troubleshooting the BPX Switch
Table 29-3 System Troubleshooting Commands Available (continued)
Command
Display Slot Alarms (dspslotalms)
Display Trunk Errors (dsptrkerrs)

Loopback Tests

Various loopback paths can be set up to help diagnose transmission problems. These rely on using
external test equipment to provide the source of a test signal.
The available loopback commands are listed in Table 29-4.
You set up a local loopback path (LL) in the local node at the PAD card (FRP) associated with the port
or connection to be tested. You then apply a test signal to the input. This passes through the associated
Interface Card (FRI), is sent to the Frame Relay PAD card (FRP) over the system bus where it is looped
back towards the input. This tests the cabling and the local node processing of the signal.

Table 29-4 System Loopback Tests

Command
Add Local Loopback
(addloclp)—frame relay port
Add Local Loopback
(addloclp)—frame relay connection
Add Local Loopback (addloclp)—data Adds a loopback path at the synchronous data port from the transmit side back to
Add Local Loopback
(addloclp)—voice
Add Remote Loopback
(addrmtlp)—frame relay port
Add Remote Loopback
(addrmtlp)—frame relay connection
Add Remote Loopback
(addrmtlp)—data
Add Remote Loopback
(addrmtlp)—voice
Add External Loopback
(addextlp)—data
A remote loopback path (RL) is set up in the remote node also at the PAD card (FRP). But, in this case,
the signal travels over the network and through the remote node processing equipment but does not
include the remote node Interface Card (FRI) or associated cabling. These components would be tested
using another local loopback at the remote node.
The external loopback command finds limited use in data applications where an external data interface
unit (DSU or CSU) is attached to the local node data interface card, illustrated by the SDI card in . The
local node transmits the appropriate loopback codes out the circuit line towards the external device and
then sets up the appropriate loopback path.
Cisco BPX 8600 Series Installation and Configuration
29-6
Description
Displays any alarms associated with the slots in a BPX node.
Displays any data errors associated with the network trunks connected to a node.
Description
Adds a loopback path at the frame relay port from the transmit side back to the
receive side at the local node.
Does the same as above only for an individual frame relay connection.
the receive side at the local node.
Adds a loopback path for an individual voice channel on a circuit line at the local
node.
Adds a loopback path at the frame relay port from the transmit side back to the
receive side at the remote node.
Does the same as above only for an individual frame relay connection.
Adds a loopback path at the synchronous data port from the transmit side back to
the receive side at the remote node.
Adds a loopback path for an individual voice channel on a circuit line at the remote
node.
Activates a near end or far end loopback on an external device, such as a DSU,
connected to a synchronous data port.
Chapter 29
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
Troubleshooting