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Octal DS3/STS-1 I/O Front Module
Plexus 9000 Planning and Engineering Guide
Issue 4, March 26, 2004
Section 130-120-600
5-156
Telica,
Inc.
5.13.3.9
DS3/STS-1 Protection Module
I/O-5 (physical slot 5) and I/O-13 (physical slot 17) are the slots for the
DS-3/STS-1 protection module in the 85-3004 or 85-3007chassis. The T3
protection bus allows the front protection module to transmit/receive eight
T3 signal pairs from rear IOMs. I/O-5 provides protection for I/O-1 to
I/O- 4 and I/O-6 to I/O-8; I/O-13 provides protection for I/O-9 to I/O-12
and I/O-14 to I/O-17. This provides N:1 redundancy for electrical
interfaces. The rear DS3/STS-1 modules contain relays that pass the
DS3/STS-1s either to the front module or to the protection bus. The rear
protection module obtains the DS-3/STS-1 from the protection bus and
passes it to the front protection module.
5.13.3.10
DS3 and STS-1 Loopbacks
DS-3 or STS-1 loopbacks can be used as diagnostics to test line integrity.
Loopbacks are always line loopbacks which loop the entire DS3
(44.736 Mb/s) or STS-1 (51.84 Mb/s)
signal. Loopbacks can occur at the
near or far end facility. The Plexus 9000 can respond to as well as initiate
loopbacks. The Plexus 9000 only responds to remote loopback requests
when operating in C-Bit mode. Likewise, FEND loopbacks on a DS3 port
can only be issued when operating in DS3 C-Bit mode. See
for DS3 line loopbacks and
for STS-1 line loopbacks of the
near-end. Loopbacks are initiated or cleared using TL1 commands.
DS3
Receive
DS3
Transmit
DS3 LOOPBACK
SUPER
MAPPER
LIU
To/From
TSU/FSU
P249-AA
03-06-01
Figure 5.13-3. DS-3 Near-end Loopback
STS-1
Receive
STS-1
Transmit
STS-1 LOOPBACK
SUPER
MAPPER
LIU
To/From
TSU/FSU
P474-AA
05-10-01
Figure 5.13-4. STS-1 Near-end Loopback