Re: [Mldonkey-users] Investigation: No download for some, fulldownloads for the other

[René Gallati]

Hello,

hope you had a nice xmas :)

> >  server it knows, then I can see there is a problem. If I remember
correctly,
> >  the official eDonkey clients asks every 15 min or so a batch of servers
to
> >  obtain sources.
> The problem is that UDP queries are not always replied by servers for
> different reasons:
> - the packet has been dropped
> - the server has decided to drop the request because of the load
> - the server never accepts UDP request

I know. However if a server is dropping excessivly UDP packets then its
overloaded. This either means a shortage of bandwith or cpu times. In any
case, its the fault of the server operator. Would mldonkey try to connect to
this server using tcp, it would most likely timeout or return in a low id
(+probably subsequent kick). That's simply a "junk" server.

Most servers answer UDPs fine. So all you do is minimize the risk by asking,
say 30 servers per iteration and do an iteration every 5 min or so. My
serverlist in mldonkey was usually around 500 servers, so that's plenty to
ask. More sources come in via source-exchange. Even more when mldonkey can
request eMule style source-exchange.

> The last one seems to be more and more frequent, because servers
> cannot accept 100000 clients sending each 20 queries for their files
> every hour.

Then these servers are not doing their job. The network was designed such as
UDP works. No wonder the old client gets problems, it relies almost
exclusively on UDP. Servers which do not process UDPs are hurting the
network. Also, blocking UDP does not make sense, the packet is still sent,
it just gets discarded / ignored, but it still takes incoming bandwith at
the servers.

> >  Also remember that all german T-DSL users lose their IP after 24 hours.
So
> >  the chances are high that you continue to pester entirely other
people's
> >  machines. (My IP is fixed, therefor I see them over days trying to
reach me)
> Yes, but trying to connect you every 6 hours is not big. If 20 000
> clients do that(you have popular files), you have 1 connection per
> second. Not a big deal, and this is probably by far the worst case.

I don't mind the bandwith, I have 1024kbits and the size of SYN packets
don't make a difference. What I mind is the rude network behaviour. Getting
three consecutive "there's nothing here" messages, each after 6 hours or
so - should make it clear once and for all that this peer should stop trying
to reach me. But I see them coming and coming and coming again. For days.
Again: I cannot say that these are mldonkey clients, they may be, they may
be something different. All I'm saying is that mldonkey should react
sensibly upon this information.

> Let's say we can try to connect every 6 hours, that was the old behavior
> in fact. It should not hurt that much, and drop the source after 3 days...

Drop it after 3 tries resulting in port closed (each try at least 6 hrs
later) - that spans 18 hrs. After 24 hrs a german T-DSL user has another IP
and won't be found again there. A port closed message is a "No", not a "try
again later" message. If the connection attempt times out, that's something
different. But for an explicit port closed sending 12 * 3 connection
attempts in 3 days is inappropriate.

--

C U

     - -- ---- ----- -----/\/  René Gallati  \/\---- ----- --- -- -