363-206-305
Circuit Pack Descriptions
Issue 3 June 2000
7-41
Control Circuitry
7
The T1EXT circuit pack interfaces with the SYSCTL over the intrashelf control
bus. Redundancy in the intrashelf control bus assures the level of control required
to perform protection switching and alarming of a faulty circuit pack. The T1EXT
provides maintenance elements for reporting the status of the circuit pack and the
incoming VT1.5 and DS1 signals, as well as the circuit pack inventory information
(
CLEI
code, date of manufacture, etc.). These maintenance elements are used by
the SYSCTL for fault detection and isolation. The T1EXT responds to control
signals from the SYSCTL for functions including protection switching. The framer
circuit acquires frame information (either SF or ESF) from the DS1 signal and
sends the information to the PM processor. The PM processor collects information
from the framing circuitry and generates near-end and far-end (ESF only) DS1 PM
parameters. When provisioned for DS1 clear channel, no PM path parameters are
generated.
Protection Circuitry
7
Optional revertive T1EXT circuit pack protection is provided with on-board relays
on the T1 line side and with logic selectors at the VT-G level on the OLIU circuit
packs. The SYSCTL controls these relays through two serial interfaces so that a
failure of one serial interface to the T1EXT does not prevent control of the relays. If
+5 V power on the T1EXT fails, the relays default to the protection state. If the
SYSCTL is removed, the relays remain in their current state.
For a mixed modem, 1X1 protection is required in a FiberReach shelf. Protection
can only be 1X1. 1X7 protection is not permitted.
Shorting contacts are provided in the backplane connectors so that when the
circuit pack is removed, the T1 line cable pairs short through to the protection bus.
To Next Page
Loading...
Need help?
General
