NS3000/iX NMMGR Screens Reference Manual - Edition 8 (36922-90038)

Chapter 4 63
Network Transport Configuration Screens
Transmission Control Protocol (TCP) Configuration
Connections may be prematurely aborted if you set retransmission
interval lower bound low and you set maximum time to wait for remote
response or maximum retransmissions per packet low. All of these
retransmission fields are configurable to optimize connection
performance. Values to be entered for the retransmission fields should,
in general, reflect the average load on system resources at the local
node, the remote node, and the intervening network(s), if any. The
optimal values for these fields can be determined only by experience for
each node.
Fields Checksum enabled
Checksumming is a method of error checking used for
reliability. TCP checksumming causes a very slight
overhead. It is not normally needed over most reliable
link types. Also, error checking is provided for at the
link level. For these reasons, HP recommends the
default value (N) for this field so that checksumming
will be disabled for this protocol.
The checksum decision for a given connection is
determined from several sources:
• The destination path report in the network directory
or probe.
• The local configuration (as specified in this screen).
• The values specified in the NetIPC intrinsics,
IPCCONNECT and IPCRECVCN.
Should any of these sources indicate checksumming
enabled, the connection will be checksummed.
The effect of disabling checksum in the configuration is
not to prohibit checksumming, but simply to allow each
connection to choose for itself. The Network Services
specify checksumming disabled in their NetIPC calls
thereby allowing control to be taken through the
configuration and network directory. Therefore, TCP
checksumming for Network Services must be specified
in the TCP Configuration screen (via the checksum
enabled field), or within the network directory.
Default value: N
Range: Y or N
Maximum
number of
connections This is a sizing parameter that allows you to configure
the number of connections based on the size of your
network (how many users there are). Each connection
functions as a separate entity in regard to destination,