Verilink HDM 2180 (880-503048-001) Product Manual - Manual (Page 12)

HDM 2180 DS3 DSU Overview
1-2 Verilink HDM 2180 User Manual
Local ASCII
Interface Port
The Local port provides the Craft interface for configuration,
control, and monitoring. A secondary function of this interface is
to provide a debug monitor port for troubleshooting.
This interface uses a 19.2 kbit/s rate and is asynchronous without
hardware flow control. The HDM 2180 Local port is RS-232
compliant for a front-panel RJ-11 connector.
SNMP Port The front panel of the HDM 2180 provides an RJ-45 SNMP port for
direct Ethernet twisted-pair communication via Telnet. The HDM
2180 embedded SNMP supports SNMPv1 and is 10BaseT compliant.
Front Panel LEDs Tri-color Network, Data Port, and System LEDs.
High-Speed Serial
Interface (HSSI)
Port
HSSI data port interface (DCE) for connection to DTE.
DS3 Network
Ports
75 Ω coaxial TX and RX DS3 network ports.
Timing Options The hardware supports three modes of system timing:
• Internal—Reference timing derived from the free-running
internal oscillator
• Network—Reference timing derived from the incoming DS3
data stream
• External—75 Ω female BNC connector accepts external timing.
The reference timing input accepts a TTL level DS3 rate clock.
Inband
Management
Channel
Specialized support is provided for the inband management
channel in C-bit parity applications. The three C-bits in M-subframe
5 of the DS3 frame are assigned as a 28.2 kbit/s terminal-to-
terminal path maintenance data link. The signal format used on
this data link consists of messages using the Link Access Procedure
on the D-channel (LAPD) protocol. A dedicated HDLC controller is
built into the hardware for this 28.2 kbit/s LAPD data link. The
controller supports polled, interrupt-driven operation.