413330 - Network timeouts

Symptom

Terminations in the communication with the application server.
10054: WSAECONNRESET: Connection reset by peer
10060: WSAETIMEDOUT: Connection timed out

Other Terms

Connection termination, WAN, Retransmit, Retransmission

Reason and Prerequisites

If a sent data package is not confirmed by the communication partner within a time window, the TCP stack will conduct a retransmit through the timeout. This means that the same data package is sent again. Retransmissions may occur when establishing the connection as well as with an existing TCP connection, but they are influenced by different parameters. The standard amounts to 3 retransmissions when establishing a connection and 5 retransmissions with an existing connection (see description below) before the TCP stack terminates the connection. The retransmission timeout is doubled after every individual retransmit. The basis timeout is also different with the two parameters. While an initial timeout of 3 seconds applies when establishing the connection, The basis timeout is dynamically determined by the measured round trip time for an existing connection. As a result of this, the basis timeout changes during an existing TCP session in accordance with the connection conditions.

Solution

The number of retransmissions can be changed by the following registry parameters:

• Establishing a connection

                    Windows NT/ Windows 2000:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\TCPIP\Parameters
Via menu 'Edit - Add Value', add 'TcpMaxConnectRetransmissions'.
Data Type: REG_DWORD
Valid Range: 0 - 0xFFFFFFFF
Default: 3

                    Windows95/ Windows98:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP
Via menu 'Edit - Add Value', add 'MaxConnectRetries'.
Data Type: String
Valid Range: 0 - 0xFFFFFFFF
Default: 3

• Existing connection:

                    Windows NT/ Windows 2000:
Via menu 'Edit - Add Value', add 'TcpMaxDataRetransmissions'.
Data Type: REG_DWORD
Valid Range: 0 - 0xFFFFFFFF
Default: 5

Windows95/ Windows98:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP
Via menu 'Edit - Add Value', add 'MaxDataRetries'.
Data Type: String
Valid Range: 0 - 0xFFFFFFFF
Default: 5

An increase by 1 corresponds roughly to a doubling of the timeout time. You may need to experiment a little with the values, to find the setting most appropriate to your requirements.

Other Attributes

Transaction codes	EDIT
Operating system	NT/INTELWIN2000

Header Data

Released On	22.01.2002 08:03:15
Release Status	Released for Customer
Component	BC-NET Network Infrastructure
Priority	Recommendations / Additional Info
Category	External error