怎么做multicast?

我想建立一个UDP服务器（在PIC32 MZ上），多个大（~8KB）缓冲区至少4x/s。可以有5个客户端读取多播数据报。我使用的是和声V2.05，XC1.44。我已经搜索了和声“帮助”文件，还有UDP和IGMP的部分，这表明这是可以做到的。但是，没有示例程序或代码片段显示如何做到这一点。我发现了一个旧的论坛线程，建议使用UDP（这是在IGMP添加到和声之前）。在该线程中，@ Runad建议查看MNS模块，但我找不到一个MNS模块，DNS模块没有提及多播。从HTTP//www. McCHIP.COM/FUMMS/M88401.ASPX（2015年5月7日），TCP/IP栈中没有IGMP支持（允许）加入/离开等。使用UDP来结束和接收多播消息是相当简单的。作为一个例子，您可以在这样做的MNS模块中查看一下。例如，您可以这样做：静态UppSosichAppSkt＝无效ID套接字；//应用程序SoCostatic静态Car AppIPv4ReMeST（20）＝“224.0.0.251”；//IPv4；多播地址静态UDPX端口AppRealPoT＝5353；//IPv4远程PotoStutuDPixPotoCalPalt＝5353；//IPv4客户端本地PosiStudio BoOL UDPyMcASTASOPEN（空隙）{IPa多地址AppEnter地址；TCPPIpHelPielStrugtoIP地址（AppIPv4ReMead，and AppMealth.V4Add）；AppSkt= TCPIpU-UdpclicliopPooporn（IpAdAddiSsSype IPv4，AppExpRead，AppLimeAdvor）；If（AppStt=＝SimuldIdSocket）{返回false；} TCPIpU.UppBIN（AppSKT，IpAddiSrSype Type IPv4，Apple CalPoT，0）；返回true；}在调用UdpMcAsTestOPEN（）之后，可以使用常规套接字函数到TX和Rx:TCPPIpUDPU-PUTISEADE，TCPIPSUDPYARADYPUT，TC，TCPIPUDUPFLUSCHPTPIPUDPGGETSIGREST，TCPPIPUDPARARYGETSO，我有2个问题：1。我应该使用UDP还是IGMP？2。我如何使用和谐API来做推荐的操作呢？



      以下为原文

    I would like to setup a UDP server (on a PIC32MZ) that multicasts a large (~8KB) buffer at least 4x/sec. There can be <5 clients that read the multicast datagrams.  I am using HARMony v2.05, XC1.44.

I have searched the Harmony "help" files and there are sections on UDP and IGMP that suggest this can be done. However, there are no example programs or code snippets showing how to do this. I did find an old forum thread that suggests using UDP (this was before IGMP was added to Harmony). In that thread, @rainad suggests looking at the mDNS module, but I cannot find an mDNS module and the DNS module does not mention multicasting.

from http://www.microchip.com/forums/m858401.aspx (May 7, 2015)

There is no IGMP support (yet) in the TCP/IP stack to allow for join/leave, etc.
However, to send and receive multicast messages using UDP is fairly simple.
As an example you can take a look in the mDNS module that does just that.
For example you could do something like this:

static UDP_SOCKET appSkt = INVALID_SOCKET; // application socket
static char appIpv4RemHost[20] = "224.0.0.251"; // IPv4 multicast address
static UDP_PORT appRemPort = 5353; // IPv4 remote port
static UDP_PORT appLocalPort = 5353; // IPv4 client local port

static bool UDP_mcast_open(void)
{
    IP_MULTI_ADDRESS appRemAddress;
    TCPIP_Helper_StringToIPAddress(appIpv4RemHost, &appRemAddress.v4Add);
    appSkt = TCPIP_UDP_ClientOpen(IP_ADDRESS_TYPE_IPV4, appRemPort, &appRemAddress);
    if(appSkt == INVALID_SOCKET)
    {
        return false;
    }
    TCPIP_UDP_Bind(appSkt, IP_ADDRESS_TYPE_IPV4, appLocalPort, 0);
    return true;
}
After calling UDP_mcast_open() you can use regular socket functions to TX and RX:
TCPIP_UDP_PutIsReady, TCPIP_UDP_ArrayPut, TCPIP_UDP_Flush
TCPIP_UDP_GetIsReady, TCPIP_UDP_ArrayGet

So, I have 2 questions:
1. Should I use UDP or IGMP?
2. How do I use the Harmony APIs to do whichever is recommended?