--- title: Multicast network in a hotel url: https://doc2.pstreamer.tv/en/manual/planning/hotels/network.html lang: en product: Perfect Streamer version: 2.0.2.423 --- # Multicast network in a hotel Channels reach the room TVs over UDP multicast: the node sends each channel once to its group, and the network delivers it only to the TVs that have joined the group by IGMP. Most hotel TV problems come from multicast misconfigured in the switches, not from the stream itself. ## A separate IPTV network - Set aside a separate VLAN for TV: the room TVs and set-top boxes, and the node’s network interface from which it sends the channels. Guest Wi-Fi, the office network and cameras go in other VLANs. - Do not let channel multicast into the guest Wi-Fi: a wireless network transmits multicast at a low rate and gets overloaded. Guests’ phones and tablets receive channels over HLS ([A single hotel](setups.md#planning-hotels-setup-single)). - On each output, set “Multicast egress interface” — the interface in the IPTV VLAN ([Output](../../webui/io/network.md#webui-io-udp-output)). On a node with several networks, without this field the system picks the interface from the routing table, and the channels may go into the wrong network. ## IGMP snooping and querier - Switch on **IGMP snooping** on all switches of the IPTV VLAN. Without it the switch floods every channel to all ports: with dozens of channels the TV port overflows, and the picture breaks up on all TVs at once. - **IGMP querier** — exactly one in the IPTV VLAN: on the router or on one of the switches. The querier periodically polls the memberships, and snooping maintains the group table from the replies. If there is no querier, snooping stops forwarding the group after a few minutes: the channel disappears for no visible reason and briefly comes back after a channel change. This is the most common mistake in hotel networks. - Switch on **Fast leave** (immediate leave from the group) on ports with a single TV or set-top box connected: channel changes get faster, and the port does not carry both channels for a while. - Switch off flooding of unknown multicast to all ports, if the switch allows it. If over time the switch forgets the node’s own membership of a multicast input channel, set “Multicast rejoin (s)” on the input — the period for rejoining the group ([Input](../../webui/io/network.md#webui-io-udp-input)). ## ASM and SSM - **ASM** (Any-Source Multicast, IGMPv2) — the TV joins a group and receives it from any sender. This is the default mode on most TVs and set-top boxes, and it is enough for a single hotel with a single node. - **SSM** (Source-Specific Multicast, IGMPv3) — the TV joins a group from a specific sender, and a second sender on the same group will not spoil the stream. SSM requires IGMPv3 on the TVs or set-top boxes and on the switches. On the input, the node receives SSM through the “SSM source address” field ([Input](../../webui/io/network.md#webui-io-udp-input)). Nothing needs to be set on the output: the SSM sender is the address of the interface from which the node sends the group. ## Addresses and TTL - Choose a group range that your TVs and set-top boxes accept: vendors can have their own rules. For example, Samsung’s guide for hospitality TVs forbids the addresses 224.x.x.x and 239.x.x.x for multicast streams and recommends 234.0.0.0–238.255.255.255 ([Samsung Developers, Multicast address rules](https://developer.samsung.com/smarttv/develop/guides/multimedia/rtp-udp-streaming.html?device=htv)). Check the vendor’s documentation and test the chosen range on a sample unit. - Take one group per channel, with the same port for all, for example 1234. - Do not use the control groups 224.0.0.x, nor groups of the form N.0.0.x and N.128.0.x with any first number: at the Ethernet level they coincide with the addresses of the control groups, and switches flood them to all ports. - Write down the address plan: group, port, channel. In a Meshwork network, the addresses and ports in use on all nodes are visible in the shared catalogue ([Shared resource catalogue](../../meshwork/map.md#meshwork-catalog)). - The output’s “IP multicast TTL” defaults to 4. Within a single VLAN even 1 is enough; if the channels pass through routers (PIM), the TTL must be greater than the number of routers on the path ([Output](../../webui/io/network.md#webui-io-udp-output)). ## Bandwidth per channel The node sends a channel at the bitrate at which it receives it, without transcoding. Guideline figures for network planning: | Channel | Codec | Bitrate, Mbit/s | | --- | --- | --- | | SD | H.264 | 2–4 | | HD (1080i/1080p) | H.264 | 6–10 | | HD (1080p) | HEVC | 3–6 | | UHD (2160p) | HEVC | 15–25 | Satellite channels often have a variable bitrate, and the peaks are noticeably higher than the average. The real bitrate of each channel is shown by the stream statistics ([Stream statistics](../../webui/streams.md#webui-stream-stats)). - **A TV port** carries only the channel being watched: 10–25 Mbit/s with headroom. - **The node port and the backbone between switches** carry all channels that are being watched in at least one room. Plan for the sum of the bitrates of all channels with 20–30 % headroom: 60 HD channels at 8 Mbit/s come to about 500 Mbit/s, which is already half of a 1 Gbit/s port ([Server sizing](sizing.md#planning-hotels-sizing)). ## What to check on the switches - IGMP snooping is on in the IPTV VLAN on every switch along the path. - There is exactly one IGMP querier in the IPTV VLAN, and it is working. - Fast leave is on for the TV ports. - Unknown multicast is not flooded to all ports. - The switch’s group table holds all channels with room to spare. - The backbone ports and the node port are rated for the sum of the bitrates of all channels. - IPTV multicast does not get into the guest Wi-Fi or other VLANs. A check from a TV: change several channels and leave one on for 10 minutes. If the channel disappears after a few minutes, check the querier; if the picture breaks up on all TVs, check snooping.