4.3BSD-UWisc/man/cat8/XNSrouted.8c

XNSROUTED(8C)       UNIX Programmer's Manual        XNSROUTED(8C)



NAME
     XNSrouted - NS Routing Information Protocol daemon

SYNOPSIS
     /etc/XNSrouted [ -s ] [ -q ] [ -t ] [ _l_o_g_f_i_l_e ]

DESCRIPTION
     _X_N_S_r_o_u_t_e_d 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 ker-
     nel routing table entries.

     In normal operation _X_N_S_r_o_u_t_e_d listens for routing informa-
     tion packets.  If the host is connected to multiple NS net-
     works, it periodically supplies copies of its routing tables
     to any directly connected hosts and networks.

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

     When a _r_e_q_u_e_s_t packet is received, _X_N_S_r_o_u_t_e_d formulates a
     reply based on the information maintained in its internal
     tables.  The _r_e_s_p_o_n_s_e 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
     _r_e_l_a_t_i_v_e _t_o _t_h_e _s_e_n_d_e_r.

     _R_e_s_p_o_n_s_e packets received by _X_N_S_r_o_u_t_e_d are used to update
     the routing tables if one of the following conditions is
     satisfied:

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

     (2)  The source host of the packet is the same as the router
          in the existing routing table entry.  That is, updated
          information is being received from the very internet-
          work router through which packets for the destination
          are being routed.

     (3)  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 effective as the current



Printed 12/27/86          June 4, 1986                          1






XNSROUTED(8C)       UNIX Programmer's Manual        XNSROUTED(8C)



          route.

     (4)  The new route describes a shorter route to the destina-
          tion 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, _X_N_S_r_o_u_t_e_d records the change in
     its internal tables and generates a _r_e_s_p_o_n_s_e packet to all
     directly connected hosts and networks.  _R_o_u_t_e_d 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, _X_N_S_r_o_u_t_e_d 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 con-
     nected hosts and networks.

     Supplying the -s option forces _X_N_S_r_o_u_t_e_d to supply routing
     information whether it is acting as an internetwork router
     or not.  The -q option is the opposite of the -s option.  If
     the -t option is specified, all packets sent or received are
     printed on the standard output.  In addition, _X_N_S_r_o_u_t_e_d will
     not divorce itself from the controlling terminal so that
     interrupts from the keyboard will kill the process.  Any
     other argument supplied is interpreted as the name of file
     in which _X_N_S_r_o_u_t_e_d'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.

SEE ALSO
     ``Internet Transport Protocols'', XSIS 028112, Xerox System
     Integration Standard.
     idp(4P)













Printed 12/27/86          June 4, 1986                          2