Sync-RrasRoutes.ps1

function Get-RrasRoutes {
    $config = netsh routing dump 
    $config | ? { $_.StartsWith("add persistentroute") } | ForEach-Object {
        $line = $config | ? { $_.StartsWith("add persistentroute") } | Select -First 1
        $line = $_
        $fields = $line -split " "
        $route = @{}
        foreach($item in $fields) {
            #$item = $fields | Select -First 1 -Skip 2
            $f = $item -split "="
            if($f.Length -eq 2) {
                switch ($f[0]) {
                    "dest" {
                        $route["Prefix"] = $f[1]
                    }
                    "mask" {
                        $route["Mask"] = $f[1]
                    }
                    "name" {
                        $route["Interface"] = $f[1].Replace('"', "")
                    }
                    "nhop" {
                        $route["Via"] = $f[1]
                    }
                }
            }
        }
        [PSCustomObject]$route
    }

}

$csvRoutes = Import-Csv -Delimiter ";" -Encoding UTF8 -Path .\routes.csv
$existingRoutes = Get-RrasRoutes
$dryRun = $false

$csvRoute = $csvRoutes | Select -First 1 -Skip 1
foreach($csvRoute in $csvRoutes) {
    $existing = $existingRoutes | Where-Object { $_.Prefix -eq $csvRoute.Prefix -and $_.Mask -eq $csvRoute.Mask }
    if($existing) {
        if($existing.Via -ne $csvRoute.Via -or $existing.Interface -ne $csvRoute.Interface) {
            " [*] Update [dest=$($csvRoute.Prefix) mask=$($csvRoute.Mask) name=`"$($existing.Interface) -> $($csvRoute.Interface)`" nhop=$($existing.Via) -> $($csvRoute.Via)]"
            if(-not $dryRun) {
                $result = & netsh routing ip delete persistentroute dest=$($existing.Prefix) mask=$($existing.Mask) name=`"$($existing.Interface)`" nhop=$($existing.Via)
                if(($result | Select -First 1) -ne "Ok.") {
                    $result
                }

                $result = & netsh routing ip add persistentroute dest=$($csvRoute.Prefix) mask=$($csvRoute.Mask) name=`"$($csvRoute.Interface)`" nhop=$($csvRoute.Via)
                if(($result | Select -First 1) -ne "Ok.") {
                    $result
                }
             }
        } else {
            " [ ] OK [dest=$($csvRoute.Prefix) mask=$($csvRoute.Mask) name=`"$($csvRoute.Interface)`" nhop=$($csvRoute.Via)]"
        } 
    }
    else {
        " [+] Add [dest=$($csvRoute.Prefix) mask=$($csvRoute.Mask) name=`"$($csvRoute.Interface)`" nhop=$($csvRoute.Via)]"
        if(-not $dryRun) {
            $result = & netsh routing ip add persistentroute dest=$($csvRoute.Prefix) mask=$($csvRoute.Mask) name=`"$($csvRoute.Interface)`" nhop=$($csvRoute.Via)
            if(($result | Select -First 1) -ne "Ok.") {
                $result
            }
        }
    }
}

$updatedRoutes = Get-RrasRoutes

$updatedRoutes | ForEach-Object {
    $rrasRoute = $_
    $csvRoute = $csvRoutes | Where-Object { $_.Prefix -eq $rrasRoute.Prefix -and $_.Mask -eq $rrasRoute.Mask -and $_.Interface -eq $rrasRoute.Interface -and $_.Via -eq $rrasRoute.Via }
    if(-not $csvRoute) {
        " [-] Remove [dest=$($rrasRoute.Prefix) mask=$($rrasRoute.Mask) name=`"$($rrasRoute.Interface)`" nhop=$($rrasRoute.Via)]"
        if(-not $dryRun) {
            $result = & netsh routing ip delete persistentroute dest=$($rrasRoute.Prefix) mask=$($rrasRoute.Mask) name=`"$($rrasRoute.Interface)`" nhop=$($rrasRoute.Via)
            if(($result | Select -First 1) -ne "Ok.") {
                $result
            }
        }
    }
}