ADTRAN 4200659L2 User Manual
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Chapter 1. Introduction

Unit Timing

The MX2800 STS-1multiplexer allows three timing methods. The first isLOOP timed, in which the multiplexer derives timing from the incomingSTS-1signal. A failure in this signal, such as a loss-of-signal(LOS) or aloss-of-framing(LOF) will cause the unit to enterHOLDOVER (HO) mode for the duration of the receive signal defect. DuringHO, the unit will continue transmitting at the same rate as the receive signal prior to entering its defect condition. Stability of the transmit duringHO is guaranteed to +/- 4.9 ppm over 24 hours. The defect condition must be cleared beforeLOOP time mode can be resumed.

The second mode of operation is FREE-RUNNING (FR) mode. In this mode, an internal oscillator is used to generate transmit timing.FREE-RUNNING mode provides a SONET minimum clock specification of +/- 20 ppm.

The third timing operation mode is EXTERNAL.EXTERNAL timing mode allows the MX2800STS-1to derive its transmit timing from any one of the 28DSX-1/E1physical ports. The ports selected may be data carrying ports. Two sources can be specified to provide external timing: a primary and a secondary source. Failure of the primary source (due to LOS or AIS) will cause the unit to switch to the secondary source, if available. In the event that both the primary and secondary sources are lost, the unit will enterHOLDOVER mode as described previously. Holdover mode will be exited upon recovery of at least one clock source.


The MX2800 STS-1'sembedded SNMP feature allows the unit to be accessed and controlled by a network manager through the 10BaseT local area network (LAN) port. The MX2800STS-1


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supports the MIB-IIstandard, RFC 1213, RFC 1595, and the ADTRAN Enterprise Specific MIB.

MIB files are available at

The term SNMP broadly refers to the message protocols used to exchange information between the network management system (NMS) and the managed devices, as well as to the structure of device management databases. SNMP has three basic components, the network manager, the agent, and the MIB.

Network Manager

The network manager is a set of control programs that collect, control, and present data pertinent to the operation of the network devices. These programs reside on a network management station.


The agent is a control program that resides in every network device. This program responds to queries and commands from the network manager, returns requested information or invokes configuration changes initiated by the manager, and sends unsolicited traps to the manager.


A MIB is an industry standard presentation of all status and configuration parameters supported by a network device.


Telnet provides a password-protected,remote login facility to the MX2800STS-1that allows a remote user to control the MX2800STS-1through the terminal menus. Only one Telnet session may be active at a time.


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Transaction Language 1 (TL1) is an ASCII based language that supports both command-responseand autonomous (NE) message generation. Commonly, TL1 is used over a X.25 packet network but is completely independent of any physical layer protocols. For the MX2800STS-1,TL1 is implemented as a Telnet session running over either Ethernet or PPP. Only one TL1 Telnet connection can be active at a time.


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The following optional equipment is available for use with the MX2800 STS-1.Contact your local distributor or theADTRAN sales department for more information (see front section of this manual for phone number).

Breakout Panel (P/N 1200291L1)

The optional breakout panel connects to the MX2800 STS-1and provides 28 RJ connectors for the individual T1s/E1s. Shipment includes twosix-foot,64-pinto64-pinAmp cables which allow direct cabling to the MX2800STS-1(seeConnecting the Breakout Panel on page 2-6 for more information).

Battery Backup (P/N 4175043L2)

The battery backup system provides power backup in the event of power loss. This system includes the battery, an AC battery charger, and an alarm cable.


MX2800 STS-1User Manual