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Supported device types and versions
Communication line configuration
Communication station configuration
I/O tags configuration
Messages of Trap type receiving and processing
Browsing and reading the tree of values from the script
Literature
Changes and modifications
Document revisions
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Protocol SNMP (Simple Network Management Protocol) is used for monitoring and administration of network components. It allows to detect detection of the status of network devices' status and change changing of their settings. In an application, it is possible to monitor the functionality of e.g. routers, switches, computers, etc.
To create a station equipped with SNMP protocol, it is necessary to have a UDP line (link type line of TCP/IP-UDP type). Its It is worth mentioning here that a TCP/IP-UDP line in the perception of the D2000 system is actually a UDP socket which is a logical device to support communication of individual stations. As the use of these sockets differs from each other in various D2000 system implementations, it It is not possible to use multiple D2000 UDP protocols on one linestations with a different protocol on a line where stations with SNMP protocol exist!
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- Communication line category: TCP/IP-UDP.
- UDP parameters:
- Host: There are three ways:
- The IP address of the particular network interface – datagrams will be transmitted and received only via this interface.
Example: 192.168.1.10 - Symbolic The symbolic name of a particular network interface.
Example: D2SRV_PRIMARY - ANY or ALL -the configured UDP port is opened on all available network interfaces. Optimal An optimal network interface should be used for communication based on routing tables. All The reception of messages will be performed on all network interfaces will receive the messages.
- The IP address of the particular network interface – datagrams will be transmitted and received only via this interface.
- Port: UDP port number (0 through 65535) from which the D2000 KOM process sends calls requests and receives the repliesresponses. If the value is 0, the port number is determined assigned automatically by OS.
Note: Ports 161 and 162 are the standard UDP ports used in SNMP but they are often reserved for SNMP agent agents - that is why it is recommended to choose different ports. There Problems can occur problems with value 0 (zero) if the network uses firewalls and other security measures. Then the particular a specific port needs to be configured on firewalls so that the packets from this port are passed via firewalls.
- Host: There are three ways:
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- firewalls.
Note:
If SNMP protocol needs to run in a redundant system, where two instances of the D2000 KOM process are running concurrently on two different computers and the IP address cannot be positively determined in the line configuration, it is suitable appropriate to choose „ANY“ or „ALL“ configuration option or to name the network addresses identically as e.g. SNMP_LAN and assign them a correct IP address in the host hosts file of each computer. See example:
| on PC1Computer 1: | 192.168.0.1 | PC1, SNMP_LAN |
| on PC2Computer 2: | 192.168.0.11 | PC2, SNMP_LAN |
Protocol parameters on the line
Following The following parameters of the protocol can be set on the line:
| Key wordKeyword | Full name | Description | Unit | Default value | ||||||||||||||||||||
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| Trace Level |
| - | 1 | ||||||||||||||||||||
| Trap Enable | Enables to receive the messages of the Trap type. | Boolean | False | ||||||||||||||||||||
| Trap IP Address | The IP address for receiving the Trap messages. | - | ANY | ||||||||||||||||||||
| Trap Port | UDP port for receiving the Trap messages. | - | 162 |
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IP_address may be set in decimal dotted notation (e.g. 192.168.0.1) or as a namename (e.g. SrvMoxa1), which assumes address translation by means of DNS or HOSTa hosts file. Address1 and Address2 concern the existence of primary and backup line lines/ routeroutes. Address 2 is usable for example for a server containing two network interface cards, which is connected to two different network segments available from via two different linesnetwork paths.
Port is a number in range 1..65535 on which an SNMP agent expects communication to take place. As the default (if not stated, or set to 0) port the standard port 161 will be used.
Note:
- IF If the line has only a primary IP address configured (numerical or symbolic), UDP packets are sent from this socket address to both IP addresses of the station. One numerical primary IP address of line + two IP addresses of the station are valid for network topology where the local network is non redundant but the remote network (where the station is located) is accessible via two redundant communication paths.
- If the line has both IP addresses configured, UDP packets to IP_address1 leave from the primary IP address of the line and UDP packets to IP_address2 leave from the backup IP address of the line.
The situation when e.g. IP_address1 is not configured conforms to the topology when the station is connected to a backup communication path only.
Protocol
Employed The employed version of SNMP protocol – one of the options can be selected:
- SNMP_V1 – the oldest version – does not support any secured access to the SNMP agent. It only distinguishes only object the objects that are freely accessible (public) and those belonging to a restricted group (private).
- SNMP_V2 – a version that supports authentication to access individual data types - an agent might (not) provide a particular set of data for an anonymous user (a manager,...) and different data for a user whose identity has been verified by entering a correct name and password.
- SNMP_V2C – the same as SNMP_V2 – the D2000 system does not distinguish these variants.
- SNMP_V3 – so far the latest protocol version – besides functions provided by SNMP_V2C, supports functions for authentication and encryption. It requires entering the name of an authentication server and authentication keys, to authenticate prior to communication with an agent, and keys for encrypting communication.
SNMP_V2, SNMP_V2C, and SNMP_V3 are not supported yet. Neither the writing into SNMP agent nor reading MIB branches as a table (structured I/O tags or directly entered structure entries) are supported.
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The following station protocol parameters can be set:
Table no. 2
| Key wordKeyword | Full name | Description | Unit | Default value | ||||||
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| Wait Timeout | Timeout period for the response to the read request. | ms | |||||||
| Retry Count | Number of re-sent read requests before the read is considered to be unsuccessful and another I/O tag will be queried. | - | |||||||
| Max Error Count | Maximum count of unsuccessful read requests, until the station changes value to StCOMERR state. A successful value delivery nullifies all counters and puts the station back into StON state. | - | |||||||
| Trace Level | The same meaning as parameter Trace Level on a line, but this setting is valid for the particular station. However, the higher value of a line parameter Trace level takes precedence. Note: Debugging of incoming packets is influenced by the line parameter Trace Level because at the time of reception it is still unknown which station the packet belongs to. | - |
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User must ensure so that the lines will not use the same network interface on the same UDP port. A line with IP address configuration as ANY basically causes blocking (restricting) UDP port on all network interfaces, which may collide with another TCP-UDP line.
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the script
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The version D2000 7.02.006 and higher supports the dynamic address change of I/O tag by TELL command SETPTADDR. This address together with I/O tag address GETNEXT_OID allow to browse and read the whole tree of values by SNMP request GetNext.
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