Trouble getting udp multicast to send

Question

5.00/5 (1 vote)

See more:

Hi there,

I was wondering if someone wouldn't mind looking at a bit of my code and help me by pointing out what I'm doing wrong. I am trying to send and receive a multicast in the same application. When i was designing the app I got it to send and receive fine on the loopback so the bulk of the programs code works fine, it's just when i tried to change over from sending a loopback to sending it as a multicast.. it fails every time I think i might not be getting the correct ip and port info to the right place.. some insight would be greatly appreciated as I am not the most proficient programmer and I have been struggling to get the app to see another instance of itself on the network with a multicast udp "ping" for lack of a better term, for the last 2 days.. Google has been helpful to a point but not much luck with any successful code on this problem..

<br />
    Public LocalHost As String = System.Net.Dns.GetHostName<br />
    Public MyIP As IPAddress = (System.Net.Dns.Resolve(LocalHost).AddressList(0))<br />
    Public MyIP2 As String = Convert.ToString(MyIP)<br />
    Public MyIP3 As IPAddress = IPAddress.Parse("192.168.1.255")<br />
    Public MyIP4 As IPAddress = IPAddress.Any<br />
    Public Bytes(2000) As Byte<br />
    Public Port1 As Integer = (2001)<br />
    Public Port2 As Integer = (2002)<br />
    Public MyLocal As New IPEndPoint(MyIP3, Port1)<br />
    Public MyRemote As New IPEndPoint(MyIP4, Port2)<br />
    Public Send As New UdpClient(MyLocal)<br />
    Public Receive As New UdpClient(MyRemote)<br />
    Public Socket As New Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp)<br />
    Delegate Sub Delegate1(ByVal SntPulseVar As String)<br />
    Delegate Sub Delegate2(ByVal RePulseVar As String)<br />
    Delegate Sub Delegate3(ByVal DelNodeVar As String)<br />
    Public PulsePacket As String = (NodeNumber & " " & LocalHost & " " & MyIP2)<br />
    Public PulsePacket2 As String = ("1 Shelly 192.168.0.2 Test Packet")<br />
    Public PulseFrequency As Int32<br />
    Public InPulseStr As String<br />
    Public InPulseByt As Object<br />
    Public KillThread As Boolean<br />
    Public T As Int32<br />
    Public NodeNumber As Int32<br />
<br />
    Public Sub FrmMain_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load<br />
<br />
        Socket.Bind(MyLocal)<br />
<br />
        Receive.JoinMulticastGroup(MyIP3, 12)<br />
<br />
        BtnDis.Enabled = False<br />
      <br />
    End Sub<br />

Thanks so much for any help.

Dwayne.

Edit: I am using VS2005 win 7

Posted 16-Mar-12 8:44am

Faultyboy

Updated 16-Mar-12 9:12am

v2

Add a Solution

Comments

TRK3 16-Mar-12 17:16pm

It sounds like you are changing several things at once when you are going from a loopback to a multicast and any one of them might be the problem:

1) You are changing from unicast to multicast.
2) You are changing from a local loopbak to over the network.
3) Are you changing ports as well?

There may be firewall and router issues with send a UDP multi-cast over the network.

First, take the code that works (sending a unicast loopback) and change the target address to the other machine (and nothing else) and see if that gets through. If it doesn't, turn off firewalls on both machines temporarily and try again. If that still doesn't work, try another machine that is physically located next to yours connected via a single hub (not a switch or router or anything that might have some intelligence in it).

Assuming you get that working, then go from the directed unicast to the multicast and see what happens.

When you've got it narrowed down to one change that is breaking the "ping" then you can figure out what's wrong with that one thing, or let us know and ask for more help.

Faultyboy 17-Mar-12 13:02pm

Thank you for the reply, I will do exactly as you say and I will get back to you with the results, so as to eliminate any network related issues. It shouldn't be changing ports, there should be a port for the incoming traffic and one for the outgoing. As far as i can tell this line..

Public MyIP3 As IPAddress = IPAddress.Parse("192.168.1.255")

I don't think it is getting saved properly as an IP address. It displays "Ipaddress.system" if i remember correctly where the ip variable should be.

Anyways I will get back to you in a day or 2.. :) Ta

Peace.

Faultyboy 18-Mar-12 7:55am

I found the sample I originally used to create the app. Is this sample correct?

http://www.java2s.com/Tutorial/VB/0400__Socket-Network/UdpBroadcast.htm

How would I edit this to send and receive on the same multicast group.

P.s. There where no network issues. Problems are in the code.

Faultyboy 18-Mar-12 8:23am

Ive gone a little bit further, could anybody please tell me if this is on the right track to sending and receiving multicast udp pings...


    Public LocalHost As String = System.Net.Dns.GetHostName
    Public MyIP As IPAddress = (System.Net.Dns.Resolve(LocalHost).AddressList(0))
    Public MyIP2 As String = Convert.ToString(MyIP)
    Public GroupIP As IPAddress = IPAddress.Parse("239.255.255.255")
    Public Bytes(2000) As Byte
    Public GroupEP As New IPEndPoint(GroupIP, 1001)
    Public Send As New UdpClient(GroupEP)
    Public Receive As New UdpClient(GroupEP)
    Delegate Sub Delegate1(ByVal SntPulseVar As String)
    Delegate Sub Delegate2(ByVal RePulseVar As String)
    Delegate Sub Delegate3(ByVal DelNodeVar As String)
    Public PulsePacket As String = (NodeNumber & " " & LocalHost & " " & MyIP2)
    Public PulseFrequency As Int32
    Public InPulseStr As String
    Public InPulseByt As Object
    Public KillThread As Boolean
    Public T As Int32
    Public NodeNumber As Int32

    ''Frm Load''

    Public Sub FrmMain_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        Send.JoinMulticastGroup(GroupIP, 1001)
        BtnDis.Enabled = False

    End Sub

next is how i can sending and receiving..


Send.Send(Bytes, Bytes.Length, GroupEP)

 InPulseByt = Receive.Receive(GroupEP)

Thanks again.

Faultyboy 18-Mar-12 8:42am

The error is: The requested address is not valid in its context

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Faultyboy · Accepted Answer · 2012-03-21T05:46:00

Ok I got it... :) For anyone who is interested this is the code to send and receive a UDP broadcast from the same app.. you have to specify the source port and the destination port for sending and receiving..

<br />
Public EndPoint As New IPEndPoint(IPAddress.Parse("255.255.255.255"), 1001) ''Send destination port<br />
Public EndPoint2 As New IPEndPoint(IPAddress.Any, 2001) ''Receive destination port<br />
Public Bytes(2000) As Byte<br />
Public Send As New UdpClient(2001) ''Send source port<br />
Public Receive As New UdpClient(1001) '' Receive source port<br />

to send and receive i used this...

<br />
Send.Send(Bytes, Bytes.Length, EndPoint) <br />
InPulseByt = Receive.Receive(EndPoint2)<br />

Works like a charm... Hope this helps anyone else.

Peace.