Simultaneous socket connections. Is there a limit?

My client wants me to write an application that maintains 30 or 40 
simultaneous socket connections to different hardware devices. For each 
device the throughput requirements are very small since only some small 
packets are sent occasionally at random intervals.

Is there a simultaneous limit? 30 or 40 is far more then I have ever done. I 
don't want any surprises. Is there a limit?

I assume XP Professional would handle this. Correct? Would XP Home be any 
different? My laptop has XP home. 


0
webster904 (54)
4/21/2005 4:35:50 AM
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To certain incoming ports, its 10, although there are several cracks out 
their to remove this limit.

You can push it up to 65,000

-- 
- Mark Randall
http://zetech.swehli.com

"Webster" <webster@mail.com> wrote in message 
news:G4G9e.992$l45.810@newssvr12.news.prodigy.com...
> My client wants me to write an application that maintains 30 or 40 
> simultaneous socket connections to different hardware devices. For each 
> device the throughput requirements are very small since only some small 
> packets are sent occasionally at random intervals.
>
> Is there a simultaneous limit? 30 or 40 is far more then I have ever done. 
> I don't want any surprises. Is there a limit?
>
> I assume XP Professional would handle this. Correct? Would XP Home be any 
> different? My laptop has XP home.
> 


0
markyr1 (230)
4/21/2005 1:11:27 PM
"Mark Randall" <markyr@REMOVETHISgoogle.ANDTHIScom> wrote in message
news:eGqKvOnRFHA.3496@TK2MSFTNGP12.phx.gbl...
> To certain incoming ports, its 10, although there are several cracks out
> their to remove this limit.
>

If you're writing your own program that uses Winsock, then that's not
correct.  There is no limit other than resources and the number of available
ports.  And for any reasonable system out there today, 30 or 40 sockets is
easy.

The limit of "10 sockets" is actually an end-user license issue, but is not
enforced by the OS.

There is also a "10 socket" limit if you use XP's built-in IIS web server,
but again, since the OP is writing his own program, that's not an issue.

Finally, there's a "10 connection" limit (i.e., connections, not sockets)
for network shares of resources on an XP Pro computer, which drops to 5
connections on XP Home.

None of these have any bearing on the concern of the OP, who should easily
be able to meet his objective.



0
4/21/2005 4:08:12 PM
XPSP2 enforces a 10 waiting-con limit full stop.

-- 
- Mark Randall
http://zetech.swehli.com

"Michael K. O'Neill" <mikeathon2000@nospam.hotmail.com> wrote in message 
news:OwoGRxoRFHA.3496@TK2MSFTNGP12.phx.gbl...
>
> "Mark Randall" <markyr@REMOVETHISgoogle.ANDTHIScom> wrote in message
> news:eGqKvOnRFHA.3496@TK2MSFTNGP12.phx.gbl...
>> To certain incoming ports, its 10, although there are several cracks out
>> their to remove this limit.
>>
>
> If you're writing your own program that uses Winsock, then that's not
> correct.  There is no limit other than resources and the number of 
> available
> ports.  And for any reasonable system out there today, 30 or 40 sockets is
> easy.
>
> The limit of "10 sockets" is actually an end-user license issue, but is 
> not
> enforced by the OS.
>
> There is also a "10 socket" limit if you use XP's built-in IIS web server,
> but again, since the OP is writing his own program, that's not an issue.
>
> Finally, there's a "10 connection" limit (i.e., connections, not sockets)
> for network shares of resources on an XP Pro computer, which drops to 5
> connections on XP Home.
>
> None of these have any bearing on the concern of the OP, who should easily
> be able to meet his objective.
>
>
> 


0
markyr1 (230)
4/24/2005 10:40:24 PM
What are the ramifications of this ?

Do you mean that there can't be more than 10 computers in a peer-to-peer network ?

Or something else ?

Mark Randall wrote:
> XPSP2 enforces a 10 waiting-con limit full stop.
> 
0
isemmel (236)
4/25/2005 8:40:33 PM
"Ian Semmel" <isemmel@removejunkmailrocketcomp.com.au> wrote in message 
news:O$HrUZdSFHA.748@TK2MSFTNGP10.phx.gbl...
> What are the ramifications of this ?
>
> Do you mean that there can't be more than 10 computers in a peer-to-peer 
> network ?
>
> Or something else ?
>
> Mark Randall wrote:
>> XPSP2 enforces a 10 waiting-con limit full stop.
>>

I think that you can have more than ten computers in a peer-to-peer network. 
What you can't have in XP is one of the computers accepting connections for 
more than the connection limit, which is 10 for XP Pro, and 5 for XP Home. 
So if one machine has a server type application on it (including a print 
server) then you'll be limited to ten clients at one time with XP Pro.  I 
have this situation in a retail office I own.

Jim H 


0
jnhtx (73)
4/25/2005 11:22:20 PM
WarezP2P has a nice little crack that wipes this limit out. Worth it :) - 
Even in a corprate situation.

-- 
- Mark Randall
http://zetech.swehli.com

"Jim Howard" <jnhtx@spamcop.net> wrote in message 
news:uG$2i2eSFHA.576@TK2MSFTNGP15.phx.gbl...
>
> "Ian Semmel" <isemmel@removejunkmailrocketcomp.com.au> wrote in message 
> news:O$HrUZdSFHA.748@TK2MSFTNGP10.phx.gbl...
>> What are the ramifications of this ?
>>
>> Do you mean that there can't be more than 10 computers in a peer-to-peer 
>> network ?
>>
>> Or something else ?
>>
>> Mark Randall wrote:
>>> XPSP2 enforces a 10 waiting-con limit full stop.
>>>
>
> I think that you can have more than ten computers in a peer-to-peer 
> network. What you can't have in XP is one of the computers accepting 
> connections for more than the connection limit, which is 10 for XP Pro, 
> and 5 for XP Home. So if one machine has a server type application on it 
> (including a print server) then you'll be limited to ten clients at one 
> time with XP Pro.  I have this situation in a retail office I own.
>
> Jim H
> 


0
markyr1 (230)
4/26/2005 12:40:11 AM
"Mark Randall" <markyr@REMOVETHISgoogle.ANDTHIScom> wrote in message
news:OAV%23g6RSFHA.3144@tk2msftngp13.phx.gbl...
> XPSP2 enforces a 10 waiting-con limit full stop.
>

I think you're referring to the SP2 changes to the TCP/IP stack, which now
limits the number of simultaneous incomplete outbound TCP connection
attempts to 10.  It's described at
http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/sp2netwk.mspx#EHAA

If so, then your response is (a) unrelated to the OP's question, (b)
unrelated to your original answer, and (c) a bit misleading (i.e., your
summary of the SP2 change is a bit misleading).

For point (a), the OP asked about "maintaining ... simultaneous socket
connections".  The change in SP2 does *not* limit the total number of
simultaneous connections in any way (as is wrongly reported and
misunderstood at many sites); it only applies to "incomplete outbound
connections", where the client has sent a SYN packet but hasn't yet received
a SYN-ACK packet from the server. So, it doesn't affect the final number of
actual connections, but it might limit the speed with which those
connections can be made.

For point (b), in your initial answer you said that "To certain incoming
ports, it [i.e., the limit] is 10...."  The SP2 change does not affect
*incoming* connections; it only affects outbound connections.

For point (c), the Microsoft Technet link given above is clear in its
description of the SP2 change:

"Limited number of simultaneous incomplete outbound TCP connection attempts

"The TCP/IP stack now limits the number of simultaneous incomplete outbound
TCP connection attempts. After the limit has been reached, subsequent
connection attempts are put in a queue and will be resolved at a fixed rate.
Under normal operation, when applications are connecting to available hosts
at valid IP addresses, no connection rate-limiting will occur. When it does
occur, a new event, with ID 4226, appears in the system�s event log.

"This change helps to limit the speed at which malicious programs, such as
viruses and worms, spread to uninfected computers. Malicious programs often
attempt to reach uninfected computers by opening simultaneous connections to
random IP addresses. Most of these random addresses result in a failed
connection, so a burst of such activity on a computer is a signal that it
may have been infected by a malicious program."

So, there is not a "full stop", as mentioned in your post, but rather new
outbound connection attempts are "put in a queue" and are "resolved at a
fixed rate" when the number of incomplete (sometimes called "half-open")
outbound connection attempts reaches the limit of 10.  And under normal
circumstances, where you are attempting to connect to a valid IP address
that is responsive, there will never be any limitations anyway because the
target servers will respond very quickly with a SYN-ACK packet and thus
complete the connections before bumping up against the limit.

Mike


0
4/26/2005 1:54:45 AM
Reply:

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