RE: UDP Question
- From: "Jim Harrison" <Jim@xxxxxxxxxxxx>
- To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx>,"[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx>
- Date: Fri, 11 Feb 2005 13:46:12 -0800
Inline...
________________________________
From: David Farinic [mailto:davidf@xxxxxxx]
Sent: Fri 2/11/2005 11:24 AM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: UDP Question
http://www.ISAserver.org
>"Games use UDP because it doesn't require them to write their apps to handle
>Winsock connection states, which are more difficult than simply barfing
>packets."
Hmm I would opposite that. If they would just barf packets soon nobody would be
able connect to server as it would be overflowed.
[Jim] - ..and they often do for just that reason. UDP is, by definition,
connectionless - packets are simply barfed (see, I said it again) between hosts
without any regard for receipt.
Tcp/ip is much easier to code with. Almost everything is handled by it. To make
working/efficient UDP communication is much more difficult. Think packet loss,
data corruption/verification, delayed packets( disordering- over jumping),
pipe overflow etc... but all these "troubles" gives you lower level data
flow control which means new features/options.
[Jim] - ?? TCP/IP is not "separate" from UDP; it encompasses it. Also, it's an
extremely rare game that actually has hooks into the TCP/IP stack; they use
Winsock calls aolmost to a man.
And ONE of them is ability to make time sensitive data transfers - transfer
where information has value only in certain time window. These are applications
with specific needs which tcp/ip as generic connection oriented protocol can
not offer.
[Jim] TCP/IP
0x56058's 2 Euro cents
________________________________
From: Jim Harrison [mailto:Jim@xxxxxxxxxxxx]
Sent: Friday, February 11, 2005 7:49 PM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: UDP Question
http://www.ISAserver.org
Just because you "see" it that way doesn't make it true.
Lots of folks think Elvis is alive and well; that doesn't make it true, either.
Nothing about UDP makes it "time sensitive", regardless of how you want to
interpret it.
UDP is more efficient "on the wire" than TCP because there's no connection
state to maintain when sending packets, but this is offset by the fact that the
application is now required to handle all the packet reassembly and ordering.
Where would you rather "waste" CPU cycles; in user or Kernel mode? TCP packet
reassembly operates in Kernel mode (more efficient), while UDP packet
reassembly operates in user mode (less efficient).
Yeh; I'll defer to games for my TCP/IP references - they're certainly the
defining force in the network world, yup-yup. Games use UDP because it doesn't
require them to write their apps to handle Winsock connection states, which are
more difficult than simply barfing packets. They also prefer UDP because as
you pointed out, it allows them to ignore packets that arrive out of sequence.
This is also true of PCAW.
________________________________
From: TRadtke@xxxxxxxxxxxx [mailto:TRadtke@xxxxxxxxxxxx]
Sent: Fri 2/11/2005 7:01 AM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: UDP Question
http://www.ISAserver.org <http://www.ISAserver.org>
So Jim, you'd use TCP for streaming video? I'd call that time sensitive,
and if the packet is out of sequence, it's useless. No need for TCP there.
How about online gaming? WoW, M59, etc, they all use UDP for data
transmission. Time sensitive. Didn't get it soon enough? Why bother
processing something that you don't even need to know about. Why use TCP to
reconstruct the packet sequence when it's pointless. It wastes CPU cycles
and network card buffers to hold out of sequence packets.
PCAnywhere uses UDP for data stream for the remote desktop. Time sensitive?
Yes. Why in the hell would I want to see my mouse jump around the screen
doing things that I did a few seconds ago?
If you even bothered to understand what I wrote, you'd see that you even
agreed with me that it's non-guaranteed delivery. Data that either is there
or useless to me IS time sensitive. Just because your definition of time
sensitive is different than mine does not make my fist post any less valid
that your post.
-----Original Message-----
From: Jim Harrison [mailto:Jim@xxxxxxxxxxxx <mailto:Jim@xxxxxxxxxxxx> ]
Sent: Thursday, February 10, 2005 4:11 PM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: UDP Question
Some reading on basic TCP/IP is clearly in order...
"UDP is normally used for time sensitive information"?!? Where did you
get this? UDP in and of itself provides no delivery guarantees
whatsoever.
-----Original Message-----
From: TRadtke@xxxxxxxxxxxx [mailto:TRadtke@xxxxxxxxxxxx
<mailto:TRadtke@xxxxxxxxxxxx> ]
Sent: Thursday, February 10, 2005 1:41 PM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: UDP Question
http://www.ISAserver.org <http://www.ISAserver.org>
Well, UDP is normally used for time sensitive information. UDP delivery
is not guarantied at all. Most of the time it's used both ways if it's
being used since if I'm not getting your traffic, it really won't matter
if your not getting mine. For example, live video streams.
------------------------------------------------------
List Archives: http://www.webelists.com/cgi/lyris.pl?enter=isalist
ISA Server Newsletter: http://www.isaserver.org/pages/newsletter.asp
ISA Server FAQ: http://www.isaserver.org/pages/larticle.asp?type=FAQ
------------------------------------------------------
Other Internet Software Marketing Sites:
World of Windows Networking: http://www.windowsnetworking.com
Leading Network Software Directory: http://www.serverfiles.com
No.1 Exchange Server Resource Site: http://www.msexchange.org
Windows Security Resource Site: http://www.windowsecurity.com/
Network Security Library: http://www.secinf.net/
Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com
------------------------------------------------------
You are currently subscribed to this ISAserver.org Discussion List as:
jim@xxxxxxxxxxxx
To unsubscribe visit http://www.webelists.com/cgi/lyris.pl?enter=isalist
Report abuse to listadmin@xxxxxxxxxxxxx
All mail to and from this domain is GFI-scanned.
This mail was checked for viruses by GFI MailSecurity. GFI also develops
anti-spam software (GFI MailEssentials), a fax server (GFI FAXmaker), and
network security and management software (GFI LANguard) - www.gfi.com
All mail to and from this domain is GFI-scanned.
Other related posts:
