From: Jim McCoy <mccoy@ccwf.cc.utexas.edu>
Date: Sat, 6 Nov 93 14:58:02 PST
To: Jim_Miller@suite.com
Subject: Re: some newbie DC-net questions
In-Reply-To: <9311062129.AA16194@bilbo.suite.com>
Message-ID: <199311062256.AA00524@tramp.cc.utexas.edu>
MIME-Version: 1.0
Content-Type: text


> 1) What is happening on a DC-net when nobody is sending a message?  Is it  
> simply issuing a stream of zeros?  Are "coins" being continuously
> flipped, even when no messages are being sent?

Yes.  Lots of zeros.  Generally one would probably have a low traffic
"carrier" of zeros and then once traffic starts the system would ramp up to
a higher traffic/fast throughput system.

> 2) What does it look like (from a traffic flow perspective) when the DC-net  
> transitions from no messages being sent to a message being sent?  The
> stream of zeros becomes and bunch of ones-and-zeros?

Generally one would have a signal that when boradcast by someone indicates
that they have the token for speaking and things progress from there.  It
is basically a distributed ring network (because of the lack of true
broadcasting over any distance) and so it will follow the standard methods
and protocols for networks of that type.

> 3) What happens when two members of a "table" attempt to transmit at the
> same time?  How is this case handled?

They will get a collision.  If an even number of members transmit at once
then the bit will be the opposite of what each expects to see, if an odd
number then it will be an undetected collision.  There are fairly standard
protocols for backdown on distributed broadcast networks.


> 4) Are there any DC-net papers available for downloading via FTP?

ftp.cc.utexas.edu:/pub/cypherpunks/dc-nets  there is the chaum paper and
tim mays general outline; both were posted to the list a while back.  Once i
get motivated i will write up an outline of a proposed implementation for
mail passing I am going to try to get running to use to test the concept
and hack out any bugs...

jim