363-206-305
Maintenance Description
9-14
Issue 3 June 2000
until a fault condition has been clear for at least as long as the alarm clear delay.
Incoming signal failure conditions, AIS, and FERF signals are subject to the
provisionable holdoff delay and a fixed 15-second clear delay. Yellow signals are
not subject to holdoff or clear delays. Circuit pack failures (except control circuit
pack failures) are subject to the provisionable holdoff and clear delays. Refer to
the
set-attr-alm
and
rtrv-attr-alm
commands in Chapter 11,
"Commands and Reports."
Protection Switching
9
The DDM-2000 FiberReach Multiplexer provides equipment protection switching
of all transmission and synchronization circuit packs, and SONET standard line
protection switching for OC-1/OC-3/OC-12 lines. Installation of some protection
equipment is optional. Protection switches are caused by automatically detected
faults in the circuit packs or OC-1/OC-3/OC-12 lines and by external commands
from a CIT or TL1/X.25 interface. Refer to the
switch-fn
,
switch-ls
, and
switch-sync
commands in Section 11, "Commands and Reports." For path
switched rings, path protection switching is used. Refer to "Path Protection
Switching (Path Switched Rings)" paragraphs in this section and the
switch-
path-vt1
or
switch-path-sts1
commands in Section 11, "Commands and
Reports."
Path Protection Switching (Path Switched Rings)
9
The path switched ring application is based on the Telcordia Technologies TR-
TSY-000496/GR-1400 path protection switching scheme.
The path protection switched ring has two single-fiber counter-rotating rings as
shown in Figure 9-5. Each node on the ring terminates four fibers: a transmit and
receive fiber in each direction. The architecture of the ring is designed to protect
against any single point of failure, including a node failure, single fiber cut, or dual
fiber cut. A node failure in a ring affects only traffic dropped at the failed node.
To Next Page
Loading...
Need help?
General
