Hello Hoby,

I  know  about  it, each TCP has an order number that is re-ordered by
the  socket  layer  so it reach ICS well ordered, I never used UDP for
more than one-packet transmission protocol like Radius or NTP.


HS> Hello Dod...

HS> Just to be clear about UDP behavior... This only worked because your
HS> transmission pattern is based on a single packet exchange. That pattern
HS> basically results in a virtual ack/nack process, which orders data by
HS> default.  UDP is not only unreliable, it is also inherently UNORDERED.  So,
HS> it is possible that packets could appear out of order, if you were sending
HS> multi-packet bursts. This requires you to provide for orderly logic as well.
HS> Hence, the queue of some type.

HS> IMHO... If you need orderly, reliable transmissions... use TCP.  The speed
HS> benefit of UDP is only valuable for single packet exchanges.  Otherwise, the
HS> robust TCP overhead is much better than anything I can provide instead.

HS> Regards...

HS> Hoby

HS> -----Original Message-----
HS> Behalf Of Dod
HS> Sent: Wednesday, July 02, 2008 5:35 AM
HS> To: ICS support mailing
HS> Subject: Re: [twsocket] Force UDP source port when sending

HS> Hello Angus,

ARMSL>> No idea how that worked, maybe the client was using a different port
HS> to
ARMSL>> reply.  

HS> Absolutely, my other programs never needed to re-use same src port so
HS> I never got the problem.

ARMSL>> If you have been making use of the TSocketServer client to save
ARMSL>> application data for the reply, you'll need a rethink.  Perhaps a
ARMSL>> queue, I think there's a TList descendent that does that in modern
HS> Delphi
ARMSL>> versions.  With UDP there's always a risk of lost packets, if your
ARMSL>> transmit conflicts with a new received packet, or at least that's my
ARMSL>> minimal understanding of UDP. 

HS> UDP  packet  lost happend as they are sent and without any SYN/ACK
HS> dialog between src and dest so UDP is fast but you have to manage
HS> packet acknowledge yourself to not loose data. For my application I
HS> only receive one packet and send one packet back.

HS> regards.

HS> -- 
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