Re: Multicasting addresses

Hi xtof and all,

> For the rulebook on address assigment, see
> http://www.iana.org/assignments/multicast-addresses.
Hmmm,
"Addresses within the 232.0.1.0-232.255.255.255 are dynamically 
allocated by hosts when needed [RFC4607]"

Does this mean that 232.144.144.X
with X=0 to 255 could be a good choice for Linrad?
(easy management of an integer 0-255 in a par file)

> Regarding the use of fixed address and port numbers. The question
> is, do we want to keep compatibility with the existing multicast
> capable network MBONE that is an overlay on the current IPv4 net.
> If you want to retain compatibility with that net you need to
> dynamically request a session address/port and advertise is in
> the "multicast directory" that has by itself a group address,
> using the service annoucement protocol.
> (for those interested in the current MBONE, see Mantra
> http://www.caida.org/tools/measurement/Mantra/topology/topology.html)
Sorry, I do not understand anything of this

> My feelings is with current state of Linrad technology and
> the bandwidth required we will exclusively use this on the
> LAN, or within locally closed user environments. In that case
> it is good practice to use locally scoped multicast address
> space as per RFC2365 (just like our local 192.168. IPv4 addresses).
> This range is 239.255.0.0/16.
So you say Linrad should use 239.255.0.X with X=0 to 16.

I can do this. Should I?

> I think there will be novel uses of Linrad that could do
> with a global multicast address for example, decoded audio or
> so, with lower bandwidth requirements.
Yes, absolutely. It might be a good idea to plan for this 
already now. Linrad will listen somewhere (at some IP addr/port)
for requests. Currently the response would only be to send
calibration data, but it would be a good idea to make a
network interface that could allow the response to be to send 
narrowband data back to the IP address that issued a command
OR to start multicasting of data according to the given
command. (perhaps for a limited time)

> This information
> can be globally distributed without blowing up the MBONE,
> and for example for educational purpose would allow many
> people to "tune" into the action (like NASA-TV aso). But
> for now, I think the above is sufficient.
Hmmm, I do not understand.

> For the rulebook on port assignment, see
> http://www.iana.org/assignments/port-numbers
> Dynamic - private port numbers are 49152 to 65535.
So Linrad can use the ports 49152 to 65535 for multicasting?

What about streaming audio? If linrad outputs 6kHz 16 bit
audio, can I multicast it on my local network in a way that
makes my gateway propagate it out on the Internet so anyone
(who logged in on my site to find out IP address and port number)
can receive it with some standard application for streaming 
audio?

It seems reasonable to me that my Internet provider will not
allow anything like that.....

> Thanks for considering an implementation, I think the separation
> of acquiring and processing is very exiting. I think it will
> not be long, before we see hardware boxes similar to
> SDR-14 or IQ multicasting the data directly on the local net
> for Linrad consumption without any "PC help". Maybe we
> need a structured Linrad Data Distribution Protocol (LDDP).

The hardware I would like to see most of all is a box with a
glass fibre 100 megabit ethernet connection and with a 
d-sub sync connection by which any number of such units can
be synchronized to each other. One could then use any number
of such boxes connected to individual antennas. With glass
fibre connections we can avoid sending computer spurs into the
antennas. We may even place antennas relatively far apart and
connect the (several) sync signals on the d-sub from a master
unit to all the slaves via fibre or microwave.

We can build very high gain HF antennas this way. If the distance 
to the box is large we would use WLAN to transmit the information.

All sorts of very interestinf possibillities will arise.

I can see only one major problem. Nothing would (perhaps) prevent
me from making say a 50kHz segment of the 40 m band available
on the Internet. This could become really bad if someone in say
Japan would hear a weak SM station, SM5XXX, that my antenna picks 
up and answer on 40m to be picked up locally in Japan by someone 
who makes a wideband 40m segment available to SM5XXX......

In contrast it could be perfectly OK that I an my friends in
the local club share a couple of antennas that each one of us
uses cleverly (to linear combine the outputs) to form narrow 
beams pointing in the direction that each one of us independently 
has choosen.

Bringing network and multicasting into SDRs could have dramatic
consequences in the long run.

What do you think?

Leif / SM5BSZ

#############################################################
This message is sent to you because you are subscribed to
  the mailing list <linrad@...>.
To unsubscribe, E-mail to: <linrad-off@...>
To switch to the DIGEST mode, E-mail to <linrad-digest@...>
To switch to the INDEX mode, E-mail to <linrad-index@...>
Send administrative queries to  <linrad-request@...>