IPv4 Multicast to Ethernet Layer 2 address mapping The IGMP protocol is defined by RFC-1112 (IGMP v1), RFC-2236 (IGMP v2) and RFC-3376 (IGMP v3). End devices send IGMP membership advertisement, and routers and IGMP-aware switches listen for these IGMP membership advertisements and ensure that multicast traffic is forwarded to those end devices.
The IGMP protcol is used by hosts to inform the routers and switches on their local network that they wish to receive multicast traffic. Background on IGMP and Multicast Group Membership IGMP and Membership Tar pits where you can get stuck for days or weeks. In addition to the usual pitfalls and traps, there are several well-hidden If you want to use multicast on a Linux host with multiple network interface, There are, however, many pitfalls on the path to using multicast on a local Multicast has found adoption on local networks as an alternative to broadcast,Īnd can be efficient if the majority of network switches support IGMP snooping. Network can be difficult to configure and may not be worthwhile, but Wiser network engineers than myself have learned that multicast on a routed Processes it and sends a copy of it to each host that needs it. IPv4 multicast seems like a wonderful idea: you send one packet, your network The ESP8266 still doesn't receive any multicast datagramms.Pitfalls and Traps in Linux Multicast Pitfalls and Traps in Linux Multicast Since the time I asked this question I completely ruled out an error of the sender on the linux machine by using a verified, 100% working sender. Maybe some of you have experienced a similar behavior and are able to give me some hints, where I might be wrong. When sending a packet with a simple multicast sender (with matching IP and port), my multicast receiver on my linux laptop receives the packet, but the ESP8266 doesn't. Int len = Udp.read(incomingPacket, BUFFER_LENGTH)
Udp.beginMulticast(WiFi.localIP(), multicastAddress, multicastPort) The receiving part of my code is as follows: #include Sending to the multicast group with udp.beginPacketMulticast(addr, port, WiFi.localIP()) and udp.write(message, messageLength)works flawlessly. You can use udp.destinationIP() to tell whether the packet received was sent to the multicast or unicast address. When listening to multicast packets, replace udp.begin(port) with udp.beginMulticast(WiFi.localIP(), multicast_ip_addr, port). When sending a multicast packet, replace udp.beginPacket(addr, port) with udp.beginPacketMulticast(addr, port, WiFi.localIP()). The WiFiUDP class supports sending and receiving multicast packets on STA interface.
I was writing my code with the help of this documentation. I try to implement an ESP8266 in STA mode as multicast receiver. I am currently working on an ESP8266 with the Arduino IDE.
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