Re: Difference between INRIA and WIDE idea

[Emmanuel Duros <Emmanuel.Duros@sophia.inria.fr>]

From: izu@jcsat.co.jp

> From: Emmanuel Duros <Emmanuel.Duros@sophia.inria.fr>
> Subject: Re: Difference between INRIA and WIDE idea
> 
> >1. The tunnel among the feeds
> > I would like to go back to the definition of a feed: A router connected
> > to an unidirectional link through a send-only interface. 
> > 
> > If the UDL is a broadcast satelite link, a feed is capable of receiving
> > data from the link. The up-link (dish + transmission equipment) also
> > allows the reception of data from the link via the same dish, it can
> > behave as a receiver.
> > 
> > I am wondering if a sat link is a particular case of UDL with feeds
> > beeing capable of receiving data ?
> 
> I don't think so.
> 
> Some satellite transmitter have only Send Only Interface(SOI).
> They do not have receiver capability.
> 
> Feeds can send the packet to UDL but can not receive the
> packet from UDL.
> 
> Izu @ WIDE project

I believe it is not a big deal to make a feed capable of receiving data
from the sat link. I am not currently doing it because I only have one
feed and I don't communicate with other feeds!

Here follows the equipment we have for our experimentations:

Transmission side:

A PC running FreeBSD has several communication interfaces. One is the
Send-Only interface, the others are simple Ethernet cards.

				     VSAT station
               <--------------------------------------------------------->
   PC
    +								   1.8 m
   SOI ------------> Modulator ------------> Amplifier ---------> sat dish

The PC is connected to our local net and routes packets from the local
net to the sat link.


Reception side:

It is another PC also connected to a local network with a receive-only
interface (ROI). The reception equipment is composed of low cost
hardware: a sat dish (about 60-80 cm diameter) directly connected to the
receive-only interface.

   60 cm                     PC +
  sat dish   ------------>   ROI


The sat dish of the VSAT can be used for transmission/reception. 

Why wouldn't we plug a ROI in a feed ? 

   PC
    +								   1.8 m
   SOI ------------> Modulator ------------> Amplifier ---------> sat dish
    +                                                                |
   ROI <-------------------------------------------------------------/


A driver could support both SOI and ROI, and we then get a bidirectional
communication. Feeds can communicate with each other without the need of
tunnels or AFM group.

Maybe other transmission/reception equipment is not that easy to handle ?

Emmanuel