TCP/IP Connection

[Rick Martin]

Since moving to CIS 5.5Rev1 on a Windows 2003 SP2 Server platform, we have been experiencing many more problems establishing outbound TCP/IP connections.  We’re using pdl-tcpip with mlp_tcp.pdl.

A typical site/process has 3 threads; an inbound and 2 outbound onlys.  One of the outbound onlys is the TCP/IP thread transmitting ORU messages.  We’ve noted that if you bring up anything but the TCP/IP thread first, the TCP/IP thread will not connect; but if the TCP/IP thread is the first to be started, it connects fine.

Just did a capture and noted that when bringing up the TCP/IP thread first, we send a SYN, which is replied to with a SYN, ACK, followed by an ACK from us and the connection is open.  If the TCP/IP thread is the second to be started, we send a SYN, which is replied to with a SYN, ACK, followed by a RST from us; this continues indefinately.

Any clue why an RST is being sent in this situation?

Topic

[Chris Williams]

It might be a port number conflict.  If you have more than one thread using a given port number, only the first one to start will actually connect.

[Bryan Dort]

SP2 on Windows 2003 server has concerned me because of all of the changes that MS put in for Windows Server 2003 Scalable Networking Pack (SNP), which allows hardware acceleration for processing network packets.  I don’t have 5.5 yet; is Windows 2003 SP2 supported, or does it just state Windows 2003?

[Rick Martin]

SP2 is actually a requirement for 5.5REV1.

[Author]

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