Cisco BPX 8650, Installation And Configuration Manual

Page: 495 / 606

28-7
Cisco BPX 8600 Series Installation and Configuration
Release 9.3.30, Part Number 78-12907-01 Rev. E0, May 2005
Chapter 28 Troubleshooting
Troubleshooting the BPX Switch
A remote loopback path (RL) is set up in the remote node also at the Frame Relay card (FRM). 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
Figure 28-1. The local node transmits the appropriate loopback codes out the circuit line towards the
external device and then sets up the appropriate loopback path (see Figure 28-1).
Figure 28-1 Network Loopback Paths
Add Remote Loopback ( addrmtlp )—voice Adds a loopback path for an individual voice channel on a circuit line at
the remote node.
Add External Loopback ( addextlp )—data Activates a near end or far end loopback on an external device, such as a
DSU, connected to a synchronous data port.
Table 28-4 System Loopback Tests (continued)
Command Description
Local node Remote node
U
X
M
F
R
M
B
C
F
R
I
B
C
U
X
M
F
R
I
F
R
M
LL
RL
User
device
User
device
S5193
LL = Local Loopback path RL = Remote Loopback path
Local node
S
D
I
DSU
S
D
P
Loop
code
S5194