redirect from treeview nodes

<asp:TreeView ID="TreeView1" runat="server"
          onselectednodechanged="TreeView1_SelectedNodeChanged">
      <Nodes>
      <asp:TreeNode Text="1" Value="1"></asp:TreeNode>
      <asp:TreeNode Text="2" Value="2"></asp:TreeNode>
      <asp:TreeNode Text="3" Value="3"></asp:TreeNode>
      </Nodes>
      </asp:TreeView>

protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
    {
        string nodeval = TreeView1.SelectedNode.Value;
        switch (nodeval)
        {
            case "1": { UpdatePanel1.Visible = true;}
                break;
            case "2": UpdatePanel2.Visible = true;
                break;
            case "3": UpdatePanel3.Visible = true;
                break;
            default: break;
        }

    }