[linux-dvb] Re: MPE MAC broadcast

[Hamish Moffatt <hamish@cloud.net.au>]

On Fri, Feb 04, 2005 at 04:44:58PM +0100, Evangelos Stergiou wrote:
> >Well, either I don't understand, or I wasn't clear with this.
> >
> >I transmit IP data with a MPE MAC broadcast enveloppe over satellite.
> >I cannot receive my IP data on my DVB-S card unless its MAC is 
> >FF:FF:FF:FF:FF:FF or I put it on promisc mode. I mean "any data", not even 
> >those having destination IP = my card's unicast IP.
> >
> >I am a satellite service provider. Suppose I have a park of a thousand 
> >receiving sites (which I do have).
> >My gateway encapsulates my IP data into a MPE MAC broadcast enveloppe 
> >(much easier than having all my sites configured to the same MAC).

I don't know anything about DVB data transmission. But your description
makes perfect sense for Ethernet, for example.

Each station only receives messages which are addressed to its MAC
address, or sent to the broadcast address. If you want to listen to all
traffic, you use promiscuous mode.

It doesn't matter what the IP address is; the MAC function will discard
any packets without the correct MAC address before the IP address is
checked. So packets with your IP address sent to the wrong MAC address
are not useful.

I think you need to either correctly set the MAC address for each packet
you are sending (based on the IP address to which its sending, eg
through ARP) or send all packets to the broadcast address.


Hamish
-- 
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>