RE: UDP Question

  • From: "Thomas W Shinder" <tshinder@xxxxxxxxxxx>
  • To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx>
  • Date: Fri, 11 Feb 2005 13:27:53 -0600

I'd stay with 'barfing packets'. It reflects a much richer user
experience.
 
Tom
www.isaserver.org/shinder <http://www.isaserver.org/shinder> 
Tom and Deb Shinder's Configuring ISA Server 2004
http://tinyurl.com/3xqb7 <http://tinyurl.com/3xqb7> 
MVP -- ISA Firewalls

 

________________________________

From: Jim Harrison [mailto:Jim@xxxxxxxxxxxx] 
Sent: Friday, February 11, 2005 1:21 PM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: UDP Question


http://www.ISAserver.org


I'll start with "monkeys & buckets" again if you don't watch out...

:-)


________________________________

From: Thomas W Shinder [mailto:tshinder@xxxxxxxxxxx]
Sent: Fri 2/11/2005 11:18 AM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: UDP Question


http://www.ISAserver.org

He said "barfing packets" heh heh.
 
;-)
 
Tom
www.isaserver.org/shinder <http://www.isaserver.org/shinder> 
Tom and Deb Shinder's Configuring ISA Server 2004
http://tinyurl.com/3xqb7 <http://tinyurl.com/3xqb7> 
MVP -- ISA Firewalls

 

________________________________

From: Jim Harrison [mailto:Jim@xxxxxxxxxxxx] 
Sent: Friday, February 11, 2005 12:49 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

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]
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]
Sent: Thursday, February 10, 2005 1:41 PM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: UDP Question

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.



 

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