NSIP(4) BSD Programmer's Manual NSIP(4)NAMEnsip - software network interface encapsulating NS packets in IP packets
SYNOPSIS
options NSIP
#include <netns/ns_if.h>
DESCRIPTION
The nsip interface is a software mechanism which may be used to transmit
Xerox NS(tm) packets through otherwise uncooperative networks. It func-
tions by prepending an IP header, and resubmitting the packet through the
kernel's IP machinery.
The super-user can advise the operating system of a willing partner by
naming an IP address to be associated with an NS address. Presently, on-
ly specific hosts pairs are allowed, and for each host pair, an artifi-
cial point-to-point interface is constructed. At some future date, IP
broadcast addresses or hosts may be paired with NS networks or hosts.
Specifically, a socket option of SO_NSIP_ROUTE is set on a socket of fam-
ily AF_NS, type SOCK_DGRAM, passing the following 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;
};
DIAGNOSTICS
nsip%d: can't handle af%d. The interface was handed a message with ad-
dresses formatted in an unsuitable address family; the packet was
dropped.
SEE ALSOintro(4), ns(4)HISTORY
The nsip interface appeared in 4.3BSD.
BUGS
It is absurd to have a separate pseudo-device for each pt-to-pt link.
There is no way to change the IP address for an NS host once the encapsu-
lation interface is set up. The request should honor flags of
RTF_GATEWAY to indicate remote networks, and the absence of RTF_UP should
be a clue to remove that partner. This was intended to postpone the ne-
cessity of rewriting reverse ARP for the en(4) device, and to allow pass-
ing XNS packets through an Arpanet-Milnet gateway, to facilitate testing
between some co-operating universities.
4.3 Berkeley Distribution November 30, 1993 1
