HP-UX 11i September 2001 Release Notes

Internet and Networking Services
Network Transport (new at 11i original release)
Chapter 10
161
Virtual IP (VIP) Address for the System
Using the loopback interface lo0:1, lo0:2 and so on, the system will respond to the IP
address assigned to these interfaces using any physical interface. Thus, a system can
now have a “systemIP” address that will be available as long as one interface stays
usable.
In some configurations, a system needs to keep a “well known” IP address that will
always be available even if an interface goes down. With the new VIP feature, a remote
user can specify an IP address that will respond regardless of the local interface where
the packet arrived. This feature is an enhancement.
setsockopt()
The system-wide kernel parameters, tcp_recv_hiwater_max (for TCP sockets) and
udp_recv_hiwater_max (for UDP sockets), now limit the maximum buffer sizes
specified in the SO_SNDBUF or SO_RCVBUF setsockopt() parameters.
A setsockopt() call with a SO_SNDBUF or SO_RCVBUF option that exceeds the
corresponding kernel parameter value will fail, returning the errno value EINVAL.
If you determine that certain applications always ask for the largest socket buffer
allowed, then you may want to set these variables and limit the amount of memory used
by such applications. When an application opens enough of these large sockets and the
system does not contain a lot of memory, then the system may starve for memory if the
application quits reading from the socket.
Applications that request sockets with send or receive buffers larger than high-water
marks set by the administrator will fail. The errno value returned is EINVAL.
T_OPTMGMT
Kernel parameters tcp_recv_hiwater_max (for TCP sockets, default 2GB) and
udp_recv_hiwater_max (for UDP sockets, default 2GB) now limit the XTI_RCVBUF
parameter maximum buffer size. Kernel parameter tcp_xmit_hiwater_max (default
2GB) now limits the XTI_SNDBUF parameter’s maximum buffer size.
A t_optmgmt() call with a tdsu or etsdu option that exceeds the corresponding kernel
parameter value will fail with TBADOPT.
If you determine that certain applications always ask for the largest buffer or transport
service data unit (tsdu) allowed, then the administrator may want to set these variables
and limit the amount of memory used by such applications.
When an application opens enough of these large sockets and the system does not
contain a lot of memory, then the system may starve for memory if the application quits
reading from the endpoint.
Applications that request sockets with buffers or tsdus larger than high-water marks set
by you will fail. The t_optmgmt() function returns the t_errno value TBADOPT.