TCP/IPv6 Configuration and Management Manual (G06.29+, H06.03+, J06.03+)

NonStop TCP/IPv6 Protocols and Configuration Files
HP NonStop TCP/IPv6 Configuration and Management Manual—524523-012
D-4
Raw Sockets
Raw Sockets
As for TCP and UDP, described earlier, application processes call a socket routine to
request the NonStop TCP/IPv6 software to create a raw socket when needed. A raw
socket provides direct access to the IP. Raw sockets allow applications to take
advantage of protocol features not directly accessible through the TCP or UDP
interfaces. Applications also can develop new protocols by using raw sockets.
Programming at the IP level by using raw sockets requires the application to provide
support for the transport protocol used above IP. If your application program refers to a
transport protocol by name, the program must provide an entry, including the protocol
number and name, in the file $SYSTEM.ZTCPIP.PROTOCOLS, as described in
Section 1, Quick Start.
For a detailed description of the socket library routines available, refer to the TCP/IP
Programming Manual. For more information on the IP, refer to RFC 791 (DDN Protocol
Handbook, Volume 2, DDN Network Information Center, December, 1985, pp. 2-99
through 2-150). Also, refer to the book TCP/IP Illustrated by W. Richard Stevens,
Prentice Hall, 1994.
Internet Control Message Protocol (ICMP)
The NonStop TCP/IPv6 software uses the Internet Control Message Protocol (ICMP)
with the IP to report errors and other control information from destination systems or
gateways.
ICMP uses the Address Resolution Protocol (ARP) to convert 32-bit internet (IP)
addresses into 48-bit Ethernet addresses. NonStop TCP/IPv6 software uses the
Internet Control Message Protocol (ICMP, RFC 792) along with IP to report errors and
other control information from destination systems or gateways. The ICMP is
considered a required part of any IP implementation.
For more information on the ICMP, refer to RFC 792 (DDN Protocol Handbook, Volume
2, DDN Network Information Center, December, 1985, pp. 2-151 through 2-172). Also,
refer to the book TCP/IP Illustrated by W. Richard Stevens, Prentice Hall, 1994.
ICMP Router Discovery Protocol
RFC 1256 defines the ICMP Router Discovery Protocol (IRDP) which uses ICMP
messages on the host side to solicit default routes from routers on the local attached
LAN and on the router side to advertise the availability of default routes. If multiple
redundant routers are present, IRDP can detect secondary routes when a primary
route fails. This secondary use of RFC 1256 is described by HP as Alternate Route
Selection.
A default route is a path from a host to a router along which the host forwards IP
packets that are destined for some non-local LAN. The router must figure out the path
to the destination LAN. This method effectively delegates all routing responsibilities to
the router, which is the recommended procedure for NonStop TCP/IPv6 in most LAN
configurations. Without IRDP, the NonStop TCP/IPv6 administrator must configure