Simulation of real time network scenarios - SNMP Devices
Simulation Toolkit's Behavior Simulation feature offers powerful
built-in SNMP script APIs and RMI client APIs to automate a complete
network environment. For example, you can start and stop individual
devices in the network at runtime, schedule network state that change
SNMP variables, add/delete rows dynamically, update node values,
change interface status, generate SNMP v1,v2c,v3 traps/inform messages,
create error conditions and scenarios, make agents stop responding
to SNMP requests etc.
Common test scenarios that can be setup using the SNMP script
APIs and RMI client APIs
Some of the common test scenarios that can be setup using the
SNMP script API and RMI client APIs are given below. These simulations
can be enabled dynamically without disrupting the simulation process.
To have the node values increased at a certain rate
The script api methods getNodeValue() and updateValue() can
be used to have the node values increased at a certain rate. This
can be achieved by configuring a timer-based script which will
be executed with some predefined time interval (for example, every
10 secs). The method getNodeValue() will get the corresponding
node's value and the method updateValue() will update a new value
to that node.
To send a trap to NMS on the start/stop of the agent
This can be achieved by configuring timer-based scripts to be
executed when the agent starts. The sendTrap() method will send
the required trap at agent startup. Similarly you can send a trap
to the NMS by calling the sendTrap() method before calling the
stopAgent() method.
To add SNMP devices to an existing network
The script api method addSnmpAgent() can be used to add SNMP
agents to an existing network. The new device is added to the
currently selected network using the devices present in the device
tree.
To delete SNMP devices from the existing network
This can be achieved by using the deleteSnmpAgent() method with
the specified IPAddress and Port. The device will be deleted from
the currently selected network .
To configure and send traps in bulk, for thousands of agents
This can be achieved by using the sendTrap() method. This method
takes the agent IPv4 or IPv6 Address and port number as parameters. Using
this method you can write your script file to send traps for any
number of agents.
To send link-up/link-down trap each time there is a get on
the ifAdmiStatus of a particular instance in the IF-MIB table
This can be achieved by configuring a request-based script with
the getNodeValue() and sendTrap() method. The getNodeValue() will
get the current value of the ifAdminStatus node and send a linkup/linkdown
trap based on the value.
To make addition/deletion to SNMP table rows dynamically,
based on other node values
This can be achieved by configuring a request/timer script with
the getNodeValue(), insertRow() and deleteRow() methods. The insertRow()
method is used to add a row to the table and the deleteRow() method
is used to remove an entry from the table. The getRowCount() method
can be used to get the total number of rows in the SNMP table.
To change interface status and send traps
The upInterface() can be used to make an interface active and
downInterface() can be used to down an active interface and sendTrap()
to send traps when the status is changed.
To start/stop agents
Start/stop any agent in the network by configuring scripts with
startAgent() and stopAgent() methods.
To start/stop TFTP Server
Start and stop TFTP server at runtime by configuring with startTFTPServer()
and stopTFTPServer() methods.
To upload/download Files using TFTP
Each device in the network supports TFTP client and server.
You can upload files from the TFTP client to the server or download
files from the TFTP server to the client by using the script methods
uploadFile() and downloadFile().
To delay SNMP responses
To achieve delay in SNMP responses, you can configure a script
with the following content. Here the value of the Thread.sleep()
is in milliseconds and should be greater than the time out value.
from java.lang import Thread
Thread.sleep(1000)
To get the IPaddress of a device
The ipaddress of a device can be retrieved at runtime by using
the getIpaddress() method.
To modify rows in bulk
The following script api methods can be used to modify rows
in bulk for all instances in the SNMP Table by incrementing a
column value. The script can be configured to be executed at agent
startup.
The scriptinterface.getInstances() method can be used to get
the instances of a given table. The scriptinterface.updateValue()
can be used to update the values in the table based on the instances.
To check the valid range for device values
To check the valid range for device values that is SET, the
scriptinterface.getCurrentValue() can be used to get the value
that comes with the 'SET' request. This value can be checked for
the specified range and if not within the range specified the
scriptinterface.terminateOperation() is called to terminate the
SET request.
To add rows to tables
The script method scriptinterface.insertRow() can be used to
add new row to SNMP tables, at runtime. The rows can be added
in bulk by calling the above method inside a loop.
To simulate short downed, medium downed and long downed agents
Simulation of Short Downed, Medium Downed and Long Downed agents
can be achieved by configuring "Behavior Timer scripts"
with the stopAgent() and startAgent() methods. The stopAgent()
will self terminate the agent that is running at a specific IPv4 or IPv6
address for a specific period of time and the start Agent() will
restart the agents after the specific period of time.
