NSIP(4)			 BSD Kernel Interfaces Manual		       NSIP(4)

NAME
     nsip — 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
     UNIX 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,
     only 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
     addresses formatted in an unsuitable address family; the packet was
     dropped.

SEE ALSO
     intro(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
     necessity of rewriting reverse ARP for the en(4) device, and to allow
     passing XNS packets through an Arpanet-Milnet gateway, to facilitate
     testing between some co-operating universities.

4.3 Berkeley Distribution      November 30, 1993     4.3 Berkeley Distribution

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