HP-UX TCP/IP Performance White Paper, March 2008

tcp_ip_abort_interval:

Second threshold timer for established connections.

When it must retransmit packets because a timer has expired,

TCP first compares the total time it has waited against two

thresholds, as described in RFC 1122, 4.2.3.5. If it has waited

longer than the second threshold, TCP aborts the connection.

For best results, do not set this parameter lower than

tcp_time_wait_interval.

In addition, you should not set this parameter to be less than four

minutes (240000 ms) so that the port number is not re-used

prematurely. [500,-] Default: 600000 (10 minutes)

This setting will only terminate a connection which is actively trying to send data to the other end. It will

have no effect on a connection which is idle and waiting to receive data.

Aborting a TCP connection will bypass the TIME_WAIT state, which is an integral part of TCP's correctness

algorithms. To be absolutely compliant with the spirit of the RFCs, the TIME_WAIT state should last for four

minutes. Given that an aborted connection will not go through TIME_WAIT, it is best that it too sit for at

least four minutes.

This is the second of two timer thresholds for established connections. The first threshold is

tcp_ip_notify_interval – the point at which TCP will tell IP that it thinks the current route to the

destination might not be any good.

tcp_ip_notify_cinterval:

First threshold timer during connection establishment.

If the first threshold is exceeded, TCP notifies IP that it

is having trouble with the current connection establishment

and requests IP to delete the routing table entry for this

destination. The assumption is that if no SYN-ACK has been

received for an extended period of time, there may be

network routing problems and IP should try to find a new

route. [1000,-] Default: 10000 (10 seconds)

This value is used both when applications actively establish connections via connect(), and when

applications will be passively accept()'ing connections.

tcp_ip_notify_interval:

First threshold timer for established connections.

If the first threshold is exceeded, TCP notifies IP that it

is having trouble with the current established connections

and requests IP to delete the routing table entry for this

destination. The assumption is that if no ACK has been

received for an extended period of time, there may be

network routing problems and IP should try to find a new

route. [500,-] Default: 10000 (10 seconds)