2009年5月28日 · If several independent instances of my application are in use on the same network, they could each use their own multicast address - but if they don't, they will be able to coexist anyway, they'll just have a small amount of overhead ignoring each others' packets. My packets already contain a "magic number" to avoid problems

2010年11月17日 · I was given an application that listens to a multicast address which works fine on one computer, but throws SocketExceptions on another. I apologise for the vagueness and stupidity of this question but any advice is greatly appreciated.

2012年5月22日 · The "join multicast group" operation (IP_ADD_MEMBERSHIP) is needed because it basically tells your network adapter to listen not only for ethernet frames where the destination MAC address is your own, it also tells the ethernet adapter to listen for IP multicast traffic as well for the corresponding multicast ethernet address. Each multicast IP ...

So if you have the MIS sending it to the a multicast addresses with a Source of 127.0.0.1, and the Receiver also listening for that address on the same computer is should just work. There really isn't anything magic, save for once you join a multicast group, your TCP Stack indicates that it is interested in packets to that address and it gets ...

2014年7月1日 · Multicast sends packets only to devices that are "subscribed" to the multicast group. Each multicast group normally has its own MAC address based on the IP address of the multicast group. A multicast packet can therefore be determined by looking at the multicast address. A broadcast goes out to every device on the network.

2017年6月24日 · A multicast address includes a specific I.P. address as well as the port number. And this is not what we traditionally think of the i.p. address of the machine (either client or server), which is part of the unicast protocol. Multicast addresses, in IPV4 terms, are 224.n.n.n to 239.n.n.n. Basically the first 4 bits of the adress are 1110

This option can be used to modify the delivery policy of multicast messages to sockets bound to the wildcard INADDR_ANY address. The argument is a boolean integer (defaults to 1). If set to 1, the socket will receive messages from all the groups that …

2013年4月9日 · These will only receive traffic for this multicast group. But: In practice UDP sockets which are used to receive multicast traffic are usually bound to address 0.0.0.0. These can receive UDP packets for all unicast and multicast addresses, and the server usually does some additional filtering based on the source-IP-address.

Since a multicast address begins "1110" (128+64+32+0 = 224), a packet sent to a an IP address beginning 1110 is destined for a multicast address. Therefor, a packet matching the mask 224.0.0.0/4 is destined for a multicast address. This display filter should therefor filter packets to multicast addresses only: ip.dst==224.0.0.0/4

2012年2月24日 · A multicast group is a special IP address. You join it via setsockopt() using the socket option IP_ADD_MEMBERSHIP, or e.g. in Java via MulticastSocket.joinGroup(). No port number here. If you want to join via a specific local address, use the overload that specifies a local address, or call setNetworkInterface() first.