NS3000/iX NMMGR Screens Reference Manual - Edition 9 (36922-90040)

76 Chapter4

Network Transport Conﬁguration Screens

Transmission Control Protocol (TCP) Conﬁguration

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,

ﬂow control and retransmissions. TCP connections and

NetIPC have a one-to-one correspondence for calls to

IPCCONNECT, and therefore between each Network

Service invoked by each user. There is no multiplexing