Using Timer

Question

Hello Guys please i'm working on my final year project so i'm developing a network tool that will continously ping and ip after some set of intervals, so when ever a network device is down it send and sms alert to the technician, here is what so far plss help

1. Dim Ip As String
2.         Ip = TextBox2.Text
3.         Dim a As String
4.         a = "Device is Up and Runing"
5.         Dim b As String
6.         b = "Ping Request Time Out"
7.         If My.Computer.Network.Ping(Ip) Then
8.  
9.             'MsgBox("Device is Up and Runing")
10.             ListBox1.Items.Add(a)
11.  
12.  
13.         Else
14.  
15.             'MsgBox("Ping request timed out.")
16.              ListBox1.Items.Add(b)