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From "Benoit Hudzia" <benoit.hud...@gmail.com>
Subject RE: large messages over datagram socket
Date Fri, 01 Sep 2006 15:11:13 GMT
 
The only thing you can know is the maximum size of the datagram packet that
your network interface support. The MTU (Maximum Transmission Unit), the
largest physical packet size, measured in bytes, that a network can
transmit. Any messages larger than the MTU are divided into smaller packets
before being sent (you can normally tweak that value manually).
If you need to transmit large packet over a private network (controlled
environment) try enabling jumbo frame support at the network interface level
of every devices on the network. But in general case jumbo frame and general
equipment (switch etc..)  do not mix well. 
 
The problem is as soon as your packet go through another network device with
a smaller MTU it will be fragmented in smaller packet and like it often
happen for udp over the internet it will  just simply be discarded. 
 
Benoit Hudzia
Parallel Computing Research Group
School of Computer Science & Informatics
University College Dublin
Ireland
 
Tel: +353 1 716 2403
Fax: +353 1 269 7262
E-mail: benoit [dot] hudzia [at] ucd [dot] ie
Web: <http://benoit.hudzia.googlepages.com/>  Personnal Web Page,
<http://voidreflections.blogspot.com> Blog
 
 
-----Original Message-----
From: Newcomb, Michael-P57487 [mailto:Michael.Newcomb@gdc4s.com] 
Sent: 01 September 2006 15:48
To: mina-dev@directory.apache.org
Subject: RE: large messages over datagram socket
 
I just want to do packet spanning, I don't need the guaranteed part of
TCP.
 
Also, how would I tell what the maximum size is for transmitting over a
DatagramConnector?
 
Thanks,
Michael
 
-----Original Message-----
From: Mike Grundvig [mailto:mike@electrotank.com] 
Sent: Friday, September 01, 2006 10:28 AM
To: mina-dev@directory.apache.org
Subject: Re: large messages over datagram socket
 
As soon as you start implementing guaranteed delivery and packet
spanning with UDP, you might want to take a serious look at TCP again.
It's a great deal of work to implement and if a re-delivery is required,
it will often be slower then TCP. Basically, the advantages of UDP are
lost quickly once the packets get loaded down with extras needed for
custom protocols. This is why most UDP systems are based on a
fire-and-forget mentality (like video streaming or FPS games).
 
If you have to use UDP for some other reason, completely ignore me :). 
Sadly, I'm still getting my head around MINA and so I don't have any
specific implementation advice. Good luck!
 
Michael Grundvig
Electrotank, Inc
http://www.electrotank.com
 
 
----- Original Message -----
From: "Newcomb, Michael-P57487" <Michael.Newcomb@gdc4s.com>
To: <mina-dev@directory.apache.org>
Sent: Friday, September 01, 2006 9:15 AM
Subject: large messages over datagram socket
 
 
Can you give me some clues as to how to implement this? I realize that
portions of messages could get lost, so, how would you recommend
implementing a 'best effort' type of service where large messages are
split and sent, then reassembled if all of them make it, and dropped
after some time if all of them don't...
 
Would this be a candidate for an IoFilter?
 
Also, Niklas mentioned MINA 0.9, is that a release somewhere or is that
what is in HEAD?
 
Thanks,
Michael
 

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