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09/03/2006

SNMP

What Is It?

SNMP stands for Simple Network Management Protocol. It is an application layer protocol for managing IP
(Internet Protocol) based systems. SNMP enables system administrators to manage system performance, and to find
and solve system problems. SNMP runs over UDP (User Datagram Protocol), which in turn runs over IP.

Three types of SNMP exist: SNMP version 1 (SNMPv1), SNMP version 2 (SNMPv2) and SNMP version 3
(SNMPv3). It is not the intention here to discuss the differences between various versions, only to bring attention to
the fact that IRT Electronics modules, fitted with SNMP capability, use SNMPv1.

An SNMP managed network consists of three key components: Network Management Systems (

NMS

agents

, and

managed devices

NMS

is the console through which the network administrator performs network management functions, such as

monitoring status (e.g. alarm states) and remote controlling, of a set of managed devices. One or more

NMS

s must

exist on any managed network. Generally the

NMS

is a computer running third party SNMP control software. There

are a number of third party SNMP software applications currently available on the market.

An

NMS

polls, or communicates with, an

agent

. An

agent

is a network management software module that resides in

managed device

. An

agent

has local knowledge of management information and translates that information into a

form compatible with SNMP. The

agent

, therefore, acts as an interface between the

NMS

and the managed devices.

The

NMS

sends a request message, and control commands for the managed devices, to the

agent

, which in turn

sends a response message, containing information about the

managed devices

, back to the

NMS

managed device

contains an SNMP

agent

and resides on a managed network.

Managed devices

collect and store

management information and make this information available to

NMS

s using SNMP.

Managed device

agent

variables are organised in a tree structure known as a Management Information Base (

MIB

Within the

MIB

are parameters pertaining to the

managed device

. An Object Identifier (OID) number within the

MIB

defines the managed device type. This is a unique number specific to the model of

managed device

. Other

information relating to the device is also stored, information such as alarm states, controllable settings, etc. The

MIB

tree is organised in such a way that there will be no two

MIB

files with conflicting placements.

Normally an

NMS

polls an

agent

for information relating to the

MIB

in a managed device to be sent back to the

NMS

. When certain conditions are met within the

MIB

, such as major alarm conditions, for example, the

agent

automatically sends what is known as a

trap

to the

NMS

without any prompting from the

NMS

. This allows

automatic notification of a predetermined event.

NMS

IP
Network

MIB

SNMP Agent
Protocol Engine

SNMP Agent

MIB

SNMP Agent
Protocol Engine

SNMP Agent

MIB

SNMP Agent
Protocol Engine

SNMP Agent

SNMP Block Diagram

IRT

Communications

www.irtcommunications.com

Содержание DDA-3020

Страница 1: ...ustralia IRT can be found on the Internet at http www irtelectronics com I R T Electronics Pty Ltd A B N 35 000 832 575 26 Hotham Parade ARTARMON N S W 2064 AUSTRALIA National Phone 02 9439 3744 Fax 02 9439 7439 International 61 2 9439 3744 61 2 9439 7439 Email sales irtelectronics com Web www irtelectronics com I R T C o m m u n i c a t i o n s w w w i r t c o m m u n i c a t i o n s c o m ...

Страница 2: ...n 17 This instruction book applies to units later than S N 0402001 Operational Safety WARNING Operation of electronic equipment involves the use of voltages and currents that may be dangerous to human life Note that under certain conditions dangerous potentials may exist in some circuits when power controls are in the OFF position Maintenance personnel should observe all safety regulations Do not ...

Страница 3: ... in pairs for redundancy For this configuration the ZDA 3021RH double width rear assembly is needed to link the logic sections of two modules When used as a line equaliser or distribution amplifier the DDA may be housed in any of IRT s standard Eurocard frames When used in pairs for handshake operation only 3 RU chassis types may be used so that the double width rear assembly may be used The DDA 3...

Страница 4: ... DDA SIGNAL PROCESSING JP1 2 JP1 1 JP3 T1 JP2 2 JP2 1 JP3 T2 JP2 3 CHANGE REQUEST JP1 3 O P 1 SK1 O P 4 SK9 O P 3 SK6 O P 5 SK7 GND JP2 4 GND JP1 4 Output Driver FPGA STM1 Generator Change over logic AIS Detector INPUT SK2 RL4 OUTPUTS SK4 Cable EQ PLL MON SK1 Block diagram DDA 3020 Signal path SK6 SK7 Output Driver Output Driver Output Driver Output Driver SK3 RL4 O P 3 O P 4 O P 2 O P 1 RL1 Gener...

Страница 5: ...power has failed General alarm Contact closure to ground if a Data Loss is detected OR b AIS is detected AND the AIS disable link LK 3 is not installed AIS detection is defined as a series of all 1 s in the payload of a frame Data Loss is defined as less than 120 data 1 s in 512 G 703 data rate clock periods Connectors Data BNC Alarm Krone LSA plus Indicators DC power Data loss AIS detect Module i...

Страница 6: ...l of the above cases switching will only occur if companion module is able to provide an output free of the same defects and changeover inhibit switch is not activated on either module Priority logic The priority switching in normal mode follows non reverting logic which dictates In the event of failure of main then standby DDA will assume control and become Main causing the failed path DDA to bec...

Страница 7: ...for successive binary 1s An example is given in Figure A 1 NOTE 1 For binary 0 there is always a positive transition at the midpoint of the binary unit time interval NOTE 2 For binary 1 a there is a positive transition at the start of the binary unit time interval if in the preceding time interval the level was A1 b there is a negative transition at the start of the binary unit time interval if th...

Страница 8: ... pulse after line equalisation and shaping then that pulse is not considered as a valid input to the count In any of these cases the Data Loss LED on the front panel of the module will light and the general alarm relay output will be activated connecting the general alarm output contact to ground AIS detection The data processor will detect an incoming AIS Alarm Indication Signal a series of all 1...

Страница 9: ...te DA selection Handshake mode detection Two data lines are present on the handshake connector to indicate to each module that it is to operate in handshake mode Power on reset When power is applied to the pair the power on reset signal will attempt to reset both modules However as only one module can be Main the logic processor checks for handshake operation and if detected then the module which ...

Страница 10: ...round indicates a loss of input or AIS detection 3 External changeover request connection to ground will make this module Main in handshake mode 4 Ground A third Krone type connector JP3 provides remote status of which unit is In Service Main Pin T1 Connection to ground indicates that module 1 is the In Service Main module T2 Connection to ground indicates that module 2 is the In Service Main modu...

Страница 11: ...tandby on detection of an Alarm Indication Signal AIS OUT Enable switching to Standby on detection of an Alarm Indication Signal AIS Switch settings Sw1 Front panel push button Change request to switch to In Service Main when used with ZDA 3021RH rear assembly Sw2 Front panel slide switch Inhibit Allow request to switch to In Service Main by either Sw1 or loss of signal when used with ZDA 3021RH r...

Страница 12: ... signal earth and chassis earth No attempt should be made to break this connection Installation in frame or chassis See details in separate manual for selected frame type Signal Connections G 703 data connections stand alone operation Connect the input and as many output connections as required Only good quality 75 Ohm connectors and cable should be used The use of 50 Ohm BNC connectors may cause ...

Страница 13: ...information base associated with these devices has the following OIDs Object Identities Alarms In Service or Standby mode State of Change over enable switch State of link that allows or disallows a change to Standby Status on detection of incoming AIS State of link that allows or disallows the transmission of AIS when Input Loss is detected Receive PLL locked input signal present I R T C o m m u n...

Страница 14: ...ANGE DATA LOSS INHIBIT ALLOW MON DDA 3020 DDA 3020 1 2 3 4 JP1 STM1 IN O P 1 O P 4 O P 2 O P 3 BYPASS 1 PWR FAIL 2 GEN ALARM 3 CHANGE REQ 4 GND SK 4 SK 3 SK 7 SK 6 SK 2 ZDA 3021RH T4 T3 T2 T1 JP1 O P 1 O P 2 O P 3 JP3 RL1 JP2 1 PWR FAIL 2 GEN ALARM 3 CHANGE REQ 4 GND T1 R TALLY T2 L TALLY T3 N C T4 GND O P 4 O P 5 4 3 2 1 4 3 2 1 RL2 I P 2 I P 1 SK 8 SK 5 SK 6 SK 7 SK 9 SK 3 SK 4 I R T C o m m u n...

Страница 15: ...e with SNMP The agent therefore acts as an interface between the NMS and the managed devices The NMS sends a request message and control commands for the managed devices to the agent which in turn sends a response message containing information about the managed devices back to the NMS A managed device contains an SNMP agent and resides on a managed network Managed devices collect and store manage...

Страница 16: ...rogram relevant to the module that it is plugged into Depending on the module besides the module identification parameters such as alarm states inputs and controls etc are communicated to the CDM 4000 agent via a data bus on the rear of the frame Thus the CDM 4000 collects information on what is loaded within the frame what positions they occupy and their current status for communication to the NM...

Страница 17: ...ainable from the component supplier Equipment return Before arranging service ensure that the fault is in the unit to be serviced and not in associated equipment If possible confirm this by substitution Before returning equipment contact should be made with IRT or your local agent to determine whether the equipment can be serviced in the field or should be returned for repair The equipment should ...

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