[p2p-hackers] infinite loops

[Greg Bildson]

The problem isn't infinite loops.  It is a question of total network cost of
a query.  TTL based networks are *not* trying to achieve full network
coverage of a query.  They are trying to give you a defined horizon for a
query that is likely big enough.   The costs of queries in a broadcast or
semi-broadcast network grow exponentially as the horizon increases (based on
TTL and hops).

If you try to ensure that your query will reach the entire network when the
network is 100,000 users then it will become much more expensive to do that
when the network reaches 1,000,000 users.  There has to be a cap on the
horizon and a TTL provides that cap.

You can work out some pretty staggering bandwidth measurements per node if
you assume that 1 in 100 users is sending a full network query every minute.

Thanks
-greg

> -----Original Message-----
> From: p2p-hackers-bounces at zgp.org [mailto:p2p-hackers-bounces at zgp.org]On
> Behalf Of Davide Carboni
> Sent: Friday, June 24, 2005 6:55 AM
> To: Peer-to-peer development.
> Subject: [p2p-hackers] infinite loops
>
>
> I notice that most of p2p protocols use TTL to prevent infinite loops.
> I was wondering why they do not use the following technique:
>
> - each node stores a cache of all message IDs received from neighbors
> -if an incoming message has an ID not in the cache, then the ID is
> added and the message is relayed
> -else if the incoming message has an ID alraedy in the cache it is
> simply ignored.
>
>
>
>
>
> --
> I have made this letter longer than usual because I lack the time to
> make it shorter.
> B. Pascal
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