HP-UX 11i December 2002 Release Notes

Internet and Networking Services
Network Transport
Chapter 12
242
Supported parameter values are as follows:
2 Use Timestamps option if initiated by the remote system
1 Always try to initiate the use of Timestamps option
0 Never use Timestamps option
5. With the enablement of socket caching, tcp_conn_strategy can now increase
performance by setting how many cached socket structures the system keeps. The
default value of 0 (zero) disables the feature. A value between 1 and 512 sets a
minimum of 512. Any number above 512 sets tcp_conn_strategy to that value.
Enabling socket structure caching can increase system performance if there are
many short-lived connections on the system.
6. Using the following formula, tcp_cwnd_init now allows you to configure the
sender’s initial TCP congestion window size:
Min(tcp_cwnd_init * MSS), max(2 * MSS, 4380),
where MSS is the maximum segment size for the underlying link. Default 4: (TCP
implements RFC 2414). Range: 1-4
7. To prevent a type of Denial-of-Service attack, ip_pmtu_strategy “2” is not
supported for 11i. In particular, a local system can no longer send its expected Path
Maximum Transmission Unit (PMTU) value within an ICMP_ECHO request to a
remote system or router.
Type ndd -h for an online description of tunable parameters and other
documentation.
Compatibility Issues
For the following commands, ndd displays IP addresses using the IP version 6 (IPv6)
format:
ndd -get /dev/ip ip_tcp_status
ndd -get /dev/ip ip_udp_status
ndd -get /dev/ip ip_raw_status
When ndd maps IP version 4 (IPv4) addresses to IPv6 addresses, ndd displays the IPv4
addresses with the prefix ::ffff: . However, ndd displays the remainder of the IPv4
address in dotted-decimal notation. This could cause scripts that are looking for a given
output to fail.
Performance
None of the features will degrade performance. Enabling socket caching using
tcp_conn_strategy could potentially increase performance by 10 to 20%.
netstat
There are two changes to netstat, which displays the statistics and configuration of the
networking kernel: one is to netstat -r; the other to netstat -I.
Since netstat -r no longer updates the “Use” field, netstat -r no longer displays it.