IGMP is the protocol for managing multicast group “subscriptions”. Internet Group Management Protocol (IGMP) # How does a client tell a router which multicast group it is interested in? With When the router receives multicast data, it forwards (andĭuplicates, if necessary) the data to the clients it knows about. Clients that should be reachable by a specific address form a Multicast-aware router that they are interested in data for a specificĪddress. What’s nice about this is that the server doesn’t have to know the actualĭestinations for the data stream. Many IP multicastĪre routable in internal networks, including the one used by SSDP (routable It’s also different from broadcast, which is link-local This is opposed to unicast where the source host sends data to a singleĭestination (1:1). IP multicast is a way to send a single data stream to multiple destinations Listens on port 3401, the Android app listens on port 3500. NOTE: The port number is different for different platforms. Thus, we need to allow speakers to access port 3400 on every controllers. This tells the speaker that whenever a related event happens, it should send a When a controllerĪpp starts, it sends the following message (. SSDP messages use the same format as HTTP 1.1 header fields. I will explainįor now we know that packets to address 239.255.255.250 (or to portġ900) and packets from speakers to controllers to port 1901 must be IP multicast address reserved for SSDP, which can be routed. The controller periodically sends the same search request to find speakers to For our purposes we only need to look at the packages sent by This step is performed by the Simple Service Discovery Protocol UPnP discovery protocol allows that control point to search for devices Similarly, when a control point is added to the network, the That device to advertise its services to control points on the When a device is added to the network, the UPnP discovery protocol allows The UPnP specification describes this step as These steps will let us know which ports need to be configured on our Looking at the messages exchanged between controller and speakers related to It groups the protocols into a series of steps. UPnP defines protocols for devices to communicate with each other Sonos uses Universal Plug and Play (UPnP) to announce and find In the following examples, host 192.168.0.5 is running the Sonos controller Have not tested yet which configuration is necessary to add a new speaker how IP multicast works, which allows us to discover Sonos speakers acrossĭisclaimer: I have only tested with an already configured Sonos system.how Sonos communicates over UPnP, which tells us which ports need to be open.Here I’m providing more detail and will explain This before, but the answers are either wrong (“it’s not possible”), buried in There are many reasons why one might want to have a Sonos speaker on a Sonos speakers on a dedicated subnet/VLAN Felix KlingįebruSonos speakers on a dedicated subnet/VLAN
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