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4550-mem.ib.rev0.doc 

Page 10 of 13

 27/07/2006

 

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

 
An 

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 

 

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 

Содержание Eurocard MEM-4550

Страница 1: ...nufactured in Australia 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...

Страница 2: ...vice 13 Equipment return 13 This instruction book applies to units later than S N 0411001 Operational Safety WARNING Operation of electronic equipment involves the use of voltages and currents that ma...

Страница 3: ...and half full duplex data modes The ASI port is switch selectable to operate at a payload data rate of either 10 8 Mb s or 108 Mb s The Ethernet port has automatic MDI MDI X detection This detects whe...

Страница 4: ...ex Half Duplex ASI SW 1 4 Program Number 4550 Program Number 4551 SW 1 5 ASI Payload Rate 108 Mb s 10 8Mb s SW 1 8 Enable SNMP if fitted Front Panel Indicators Ethernet LINK Ethernet link connected Gr...

Страница 5: ...N 100 Base T SW1 3 OFF Half Duplex Operation ON Full Duplex Operation Note SW1 2 and SW1 3 switch settings only work with SW1 1 set to off position ASI Parameters SW1 4 OFF ASI Program Number set to 4...

Страница 6: ...is made between 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 Ethernet Conn...

Страница 7: ...up with the three sets of multipin sockets on the main PCB module Align all pins and then gently press the SMU 4000 all the way down into place If the SMU 4000 is not already programmed with the corr...

Страница 8: ...OR 4 GND ASI OUTPUT 1 2 3 4 Front rear panel connector diagrams The following front panel and rear assembly drawings are not to scale and are intended to show connection order and approximate layout o...

Страница 9: ...s Green FDX Full Duplex Mode Green ACT LAN Activity Green ASI LINK Ethernet link connected Green 10 100 Rate 10 8 Mb s Orange 108 Mb s Green ERR Error in ASI input Red 188 Input ASI 188 byte Green Ea...

Страница 10: ...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...

Страница 11: ...tible need a plug in SMU 4000 module with a program relevant to the module that it is plugged into Depending on the module besides the module identification parameters such as alarm states inputs and...

Страница 12: ...ng received on the ASI input An indication that a link has been established on the Ethernet port An indication of which of the two available speeds that the Ethernet port is operating 10 or 100 An ind...

Страница 13: ...extended by IRT only to the extent obtainable 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...

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