Документация¶
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- Документация
Адресация¶
Livewire channels range from 0 to 32767. Audio streams are mapped into IP and Ethernet multicast addresses using the channel numbers for the lower 15 bits as follows:
IP Addressl Type
239.192.000.0/15 Livestream and Standard Stereo Streams
239.192.128.0/15 4 addresses are our system defaults, the others not used (left for expansion)
239.193.000.0/15 Back Standard Stereo Streams
239.193.128.0/15 not used (left for expansion)
239.194.000.0/15 not used (LW v1.0 used for Ethernet Livestreams)
239.194.128.0/15 not used (left for expansion)
239.195.000.0/15 Back Livestreams
239.195.128.0/15 not used (left for expansion)
239.196.128.0/15 Surround Streams
239.251.000.0/15 not used (left for expansion)
239.251.128.0/15 not used (left for expansion)
The following special addresses are assigned:
IP Addressl Function
*239.192.255.1 *Livestream Clock
*239.192.255.2 *Standard Stream Clock
*239.192.255.3 *Advertisement Channel
*239.192.255.4 *GPIO (UDP port 2060)
These all are within the range specified for "Organization-Local Scope" use by IANA – the Internet Assigned Names and numbers Authority. Routers do not propagate traffic on these addresses to the internet; they stay contained within LANs. (We also set the "link local" bit and TTL=1 in the IP header to further ensure that streams stay local.)
The range supports our 32k channels, with up to 120 stream types per channel. We are only using four types now, but there is plenty of room for growth. Our motivation for mapping each type to a contiguous block rather than having the type in the lower-order bits is to allow configuration of switches and routers on a per-type basis by specifying an address range. This direct mapping of channels to addresses also makes sniffing easier: it is simple to know where to look for a particular audio stream.
IP addresses are mapped into an Ethernet MAC layer multicast, according to a de-facto standard process for this procedure. This process is as follows:
Using the Class D address, identify the low order 23 bits of the class D address. Map those 23 bits into the low order 23 bits of a MAC address with the fixed high order 25 bits of the IEEE multicast addressing space prefixed by 01-00-5E.
Example:
Assume: Channel = 80
Assume: stream type is Standard Stereo Stream
Then: IP address = 239.192.0.80 (dotted decimal)
And then: Ethernet MAC Address = 01-00-5e-00-00-50 (dashed hex)
Ethernet addresses are transmitted most-significant byte first, but least-significant bit first within the byte, so in our example it is the 1 in the leftmost MAC address byte 01 that signifies a multicast address.
Полезный калькулятор для перевода Номера канала в мультикастовый IP
https://support.telosalliance.com/article/ewmogdoltp-calculating-a-multicast-address-from-livewire-channel-number
