The nsip interface enables a user process to encapsulate Network Services (NS) packets in Internet Protocol (IP) packets. This interface is a software mechanism that can be used to transmit Xerox Network Systems (XNS) packets through Internet networks. It functions by prepending an IP header and resubmitting the packet to the UNIX IP machinery.
The root user can advise the operating system of a partner system by naming an IP address to be associated with an NS address. Presently, only specific host pairs are allowed, and for each host pair, an artificial point-to-point interface is constructed.
The nsip interface uses the following conventions for encapsulation:
Specifically, a socket option of SO_NSIP_ROUTE is set on a socket of family AF_NS, type SOCK_DGRAM, passing the following data structure:
struct nsip_req{
struct sockaddr rq_ns; /*must be ns format destination */
struct sockaddr rq_ip; /*must be ip format gateway */
short rq_flags;
};
The nsip mechanism fails if one or more of the following are true: