Nortel Networks 553-3001-211 manual Connection characteristics, Fault detection, Fault isolation

QPC513 Enhanced Serial Data Interface card Page 845 of 894

Fault detection

Firmware on the ESDI card detects hardware faults on the card and link level LAPB protocol faults. It reports the faults to the CPU when predetermined thresholds (downloaded at initialization) have been exceeded.

Fault isolation

The ESDI/Command and Status Link (CSL) maintenance software takes the ESDI card out of service when the out-of-service thresholds are exceeded for the following:

•LAPB error conditions (for example, retransmission, Cyclic Redundancy Check (CRC) errors, overrun/underrun errors)

•Physical or link errors

•Detected hardware errors

Connection characteristics

The two DB-25 connectors on the front panel of the ESDI card provide connections to each of the two I/O ports. The electrical interface of these connectors is a modified version of the RS-422-A standard designed to drive high-speed data over long cable lengths (up to 100 ft). Table 262 shows the interconnection specifications for these ports.

Table 262

QPC513 interconnection specifications

Distance	Interconnection
<15.24 m (<50 ft)	Regular 25-conductor cable
>15.24 m and <30.48 m	Twisted pair for balanced circuits
(>50 ft and <100 ft)
>30.48 m (>100 ft)	Network interface devices such as stand-alone
	modems or DS-1 facilities using
	Asynchronous/Synchronous Interface Module
	(ASIM) and Data Line card (DLC)

Circuit Card Description and Installation