WinXP TCP Connection Limit
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So Microsoft, in their infinite wisdom, have placed a restriction on how many TCP connections can be made to a machine running XP SP2. The limit is supposedly 10 connections for XP professional. So here's the thing; after searching around the place, I've come across two different descriptions of the same topic. Some reference sites say the limit of connections applies to the total number of TCP connections made by the machine, whereas other sites say that the limit of 10 connections applies to the number of inbound connections per second, and that more connections can be made on a per second basis. I don't have 10+ extra PCs floating around so I can't exactly find out for myself, so I was wondering if anyone here knows the answer to this one.
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So Microsoft, in their infinite wisdom, have placed a restriction on how many TCP connections can be made to a machine running XP SP2. The limit is supposedly 10 connections for XP professional. So here's the thing; after searching around the place, I've come across two different descriptions of the same topic. Some reference sites say the limit of connections applies to the total number of TCP connections made by the machine, whereas other sites say that the limit of 10 connections applies to the number of inbound connections per second, and that more connections can be made on a per second basis. I don't have 10+ extra PCs floating around so I can't exactly find out for myself, so I was wondering if anyone here knows the answer to this one.
Last I tried, it was 10 inbound active connections at one time. If some of those connections are like HTTP transfers (connect, download, disconnect), then you can have the illusion of more connections at the same time.
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Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic
2006, 2007, 2008
But no longer in 2009... -
Last I tried, it was 10 inbound active connections at one time. If some of those connections are like HTTP transfers (connect, download, disconnect), then you can have the illusion of more connections at the same time.
A guide to posting questions on CodeProject[^]
Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic
2006, 2007, 2008
But no longer in 2009...That's certainly one strategy that could be applied to my current situation. The other option is to start using the UDP protocol instead, as my understanding is that this method is connectionless and therefore shouldn't get caught up in the whole restricted connection dealie. Both solutions mean a pretty significant quantity of work. Does anyone have any other suggestions?
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So Microsoft, in their infinite wisdom, have placed a restriction on how many TCP connections can be made to a machine running XP SP2. The limit is supposedly 10 connections for XP professional. So here's the thing; after searching around the place, I've come across two different descriptions of the same topic. Some reference sites say the limit of connections applies to the total number of TCP connections made by the machine, whereas other sites say that the limit of 10 connections applies to the number of inbound connections per second, and that more connections can be made on a per second basis. I don't have 10+ extra PCs floating around so I can't exactly find out for myself, so I was wondering if anyone here knows the answer to this one.
I believe the limitation you are referring to only effects half-open TCP connections. This limitation applies to outgoing TCP connections. You can easily determine if you are bumping into this limitation by using the Event Viewer[^] and looking for EVENT_TCPIP_TCP_CONNECT_LIMIT_REACHED entries[^]. The limitation was an attempt to prevent SYN Flooding[^] and other types of DDOS attacks. Apparently it was determined that this limitation was no longer necessary... its been removed in Vista SP2,Server2008 and Windows7. Best Wishes, -David Delaune
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That's certainly one strategy that could be applied to my current situation. The other option is to start using the UDP protocol instead, as my understanding is that this method is connectionless and therefore shouldn't get caught up in the whole restricted connection dealie. Both solutions mean a pretty significant quantity of work. Does anyone have any other suggestions?
Yeah, but that depends on what you're transferring. UDP does not guarantee delivery of packets, nor that the packets will get there in the correct order. It's great for streaming audio and video where dropped packets can be recovered from quite easily, but not good at all for other data.
A guide to posting questions on CodeProject[^]
Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic
2006, 2007, 2008
But no longer in 2009... -
I believe the limitation you are referring to only effects half-open TCP connections. This limitation applies to outgoing TCP connections. You can easily determine if you are bumping into this limitation by using the Event Viewer[^] and looking for EVENT_TCPIP_TCP_CONNECT_LIMIT_REACHED entries[^]. The limitation was an attempt to prevent SYN Flooding[^] and other types of DDOS attacks. Apparently it was determined that this limitation was no longer necessary... its been removed in Vista SP2,Server2008 and Windows7. Best Wishes, -David Delaune
Good to know. Cheers, dude.