parsing variables in Azure ARM template file - json

Question

i am wriiting an Azure ARM Template for deploying VNETs. Therefore i have a deployment file "VNET.json and a parameter file "VNET.parameter.json.
Now i want to hand over ONLY in the paramter File a variable but always got the error:
'The template variable 'IP' is not found. Please see https://aka.ms/arm-template/#variables for usage details.
or is it not "allowd" to use a variable in a parameter?
Here is my json file.
{
"$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"variables": {
"IP": "172.37.0.0/24"
},
"parameters": {
"VNetSettings":{
"value":{
"name":"ManagementNW",
"addressPrefixes": [
{
"name": "VPN",
"addressPrefix": "192.168.0.0/16"
},
{
"name": "Control",
"addressPrefix": "172.37.0.0/16"
},
{
"name": "Service",
"addressPrefix": "172.36.0.0/16"
},
{
"name": "DMZ",
"addressPrefix": "172.35.4.0/24"
}
],
"subnets":[
{
"name": "VPN-subnet",
"addressPrefix": "192.168.1.0/24"
},
{
"name": "Control-subnet",
"addressPrefix": "172.37.0.0/24"
},
{
"name": "Service-subnet",
"addressPrefix": "172.36.0.0/24"
},
{
"name": "DMZ-subnet",
"addressPrefix": "172.35.4.0/24"
},
{
"name": "Gateway-subnet",
"addressPrefix": "192.168.255.0/24"
},
{
"name":"AzureFirewall-subnet",
"addressPrefix":"192.168.254.0/24"
}
]
}
},
"Control-NSG-settings": {
"value": {
"securityRules": [
{
"direction": "Inbound",
"name": "VPNGW_to_Tableau_all",
"sourceAddressPrefix": "192.168.255.0/24",
"sourcePortRange": "*",
"destinationAddressPrefix": "172.37.0.41",
"destinationPortRange": "*",
"protocol": "*",
"access": "Allow",
"priority": 101,
"description": "allow RDP connections"
},
{
"direction": "Inbound",
"name": "VPNGW_to_Control_all",
"sourceAddressPrefix": "192.168.255.0/24",
"sourcePortRange": "*",
"destinationAddressPrefix": "[variables('IP')]",
"destinationPortRange": "*",
"protocol": "*",
"access": "deny",
"priority": 102,
"description": "deny"
},
KR
Marvin

Answer 1

In the template, you reference the value for the parameter by using the variables function.
In the ARM template json file, you use variables to simplify your template. Rather than repeating complicated expressions throughout your template, you define a variable that contains the complicated expression. However, if you only use once you do not need to use variables.
Also, as usrone said, your template looks suspicious. The normal template is as this one you could refer to.
{
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "",
"apiProfile": "",
"parameters": { },
"variables": { },
"functions": [ ],
"resources": [ ],
"outputs": { }
}