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XNSROUTED(8)              BSD System Manager's Manual             XNSROUTED(8)

     XNSrouted - NS Routing Information Protocol daemon

     XNSrouted [-q] [-s] [-t] [logfile]

     XNSrouted is invoked at boot time to manage the Xerox NS routing tables.
     The NS routing daemon uses the Xerox NS Routing Information Protocol in
     maintaining up to date kernel routing table entries.

     Available options:

     -q       Do not supply routing information (opposite of -s option below).

     -s       Forces XNSrouted to supply routing information whether it is
              acting as an internetwork router or not.

     -t       All packets sent or received are printed on the standard output.
              In addition, XNSrouted will not divorce itself from the control-
              ling terminal so that interrupts from the keyboard will kill the

     logfile  Name of file in which XNSrouted's actions should be logged.
              This log contains information about any changes to the routing
              tables and a history of recent messages sent and received which
              are related to the changed route.

     In normal operation XNSrouted listens for routing information packets.
     If the host is connected to multiple NS networks, it periodically sup-
     plies copies of its routing tables to any directly connected hosts and

     When XNSrouted is started, it uses the SIOCGIFCONF ioctl(2) to find those
     directly connected interfaces configured into the system and marked
     ``up'' (the software loopback interface is ignored).  If multiple inter-
     faces are present, it is assumed the host will forward packets between
     networks.  XNSrouted then transmits a request packet on each interface
     (using a broadcast packet if the interface supports it) and enters a
     loop, listening for request and response packets from other hosts.

     When a request packet is received, XNSrouted formulates a reply based on
     the information maintained in its internal tables.  The response packet
     generated contains a list of known routes, each marked with a ``hop
     count'' metric (a count of 16, or greater, is considered ``infinite'').
     The metric associated with each route returned provides a metric relative
     to the sender.

     Response packets received by XNSrouted are used to update the routing ta-
     bles if one of the following conditions is satisfied:

     o   No routing table entry exists for the destination network or host,
         and the metric indicates the destination is ``reachable'' (i.e. the
         hop count is not infinite).

     o   The source host of the packet is the same as the router in the exist-
         ing routing table entry.  That is, updated information is being re-
         ceived from the very internetwork router through which packets for
         the destination are being routed.

     o   The existing entry in the routing table has not been updated for some
         time (defined to be 90 seconds) and the route is at least as cost ef-

         fective as the current route.

     o   The new route describes a shorter route to the destination than the
         one currently stored in the routing tables; the metric of the new
         route is compared against the one stored in the table to decide this.

     When an update is applied, XNSrouted records the change in its internal
     tables and generates a response packet to all directly connected hosts
     and networks.  Routed(8) waits a short period of time (no more than 30
     seconds) before modifying the kernel's routing tables to allow possible
     unstable situations to settle.

     In addition to processing incoming packets, XNSrouted also periodically
     checks the routing table entries.  If an entry has not been updated for 3
     minutes, the entry's metric is set to infinity and marked for deletion.
     Deletions are delayed an additional 60 seconds to insure the invalidation
     is propagated to other routers.

     Hosts acting as internetwork routers gratuitously supply their routing
     tables every 30 seconds to all directly connected hosts and networks.


     Internet Transport Protocols, XSIS 028112, Xerox System Integration

     The XNSrouted command appeared in 4.3BSD.

4.3 Berkeley Distribution        June 5, 1993                                2