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Cisco ONS 15454 SDH Troubleshooting Guide, R5.0
July 2005
Chapter 1 General Troubleshooting
1.1.2 Terminal Loopbacks
1.1.2.2 ONS 15454 SDH Card Behavior
ONS 15454 SDH port loopbacks can either terminate or bridge the loopback signal. In the
ONS 15454 SDH system, all optical, electrical, Ethernet, MXP, TXP, and FC_MR facility loopbacks are
terminated as shown in Table 1-2. During terminal loopbacks, some ONS 15454 SDH cards bridge the
loopback signal while others terminate it.
If a port terminates a terminal or facility loopback signal, the signal only loops back to the originating
port and is not transmitted downstream. If the port bridges a loopback signal, the signal loops back to
the originating port and is also transmitted downstream.
ONS 15454 SDH card terminal loopback bridging and terminating behaviors are listed in Table 1-2.
Note In Table 1-2, no AIS signal is injected if the signal is bridged. If the signal is terminated, an applicable
AIS is injected downstream for all cards except Ethernet cards.
Bridged E1-N-14 and STM-N terminal loopback examples are shown in Figure 1-7 and Figure 1-8.
Figure 1-7 Terminal Loopback on an E1-N-14 Card with Bridged Signal
Table 1-2 ONS 15454 SDH Card Terminal Loopback Behavior
Card/Port Terminal Loopback Signal
DS3i-N-12 Bridged
E1-N Terminated
G-Series Ethernet Terminated
1
1. G-Series Ethernet terminal loopback is terminated and Ethernet transmission is
disabled. No AIS is inserted for Ethernet, but a TPTFAIL alarm is raised on the
far-end Ethernet port.
MXP, MXPP trunk ports Bridged
MXP, MXPP client ports Terminated
TXP, TXPP trunk ports Bridged
TXP, TXPP client ports Terminated
STM1-E in STM1-E mode Terminated
STM1-E ports 9-12 in E4 mode
2
2. For the STM1-E card, only Ports 9 through 12 can be placed in E4 mode.
Bridged
Source
ONS Node
Destination
ONS Node
XCE1N STM-N E1NXCSTM-N
Test Set
Test Set
120194
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