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routed(8)							    routed(8)



NAME

  routed - Manages network routing tables

SYNOPSIS

  /usr/sbin/routed [-dgt] [-q|-s] [logfile]

OPTIONS

  -d  Enables additional debugging information,	such as	bad packets received,
      to be logged. The	routed daemon remains under control of the host	that
      started it; therefore, an	interrupt from the controlling host stops the
      routed process.

  -g  Causes the routing daemon	to run on a gateway host. This option is used
      on internetwork routers to offer a route to the default destination.

  -q  Inhibits the routed daemon from supplying	Routing	Information Protocol
      (RIP) data.  The -q option conflicts with	the -s option.	Do not use
      the -q and -s options together.

  -s  Causes routed to supply RIP information even if it is not	functioning
      as an Internet router.  The -s option conflicts with the -q option.  Do
      not use the -s and -q options together.

  -t  Causes all packets sent or received to be	written	to standard output.
      The routed daemon	remains	under control of the host that started it;
      therefore, an interrupt from the controlling host	stops the routed pro-
      cess.

OPERANDS

  logfile
      The optional logfile operand specifies a log file	where the routed dae-
      mon writes information about its actions.	 This log contains informa-
      tion about any changes to	the routing tables and a history of recent
      route change messages sent and received that are related to changed
      routes.

DESCRIPTION

  Use the routed daemon	to manage the RIP only.	Use gated to manage RIP	plus
  other	protocols.

  When routed starts, it finds any interfaces to directly connected hosts and
  networks that	are configured into the	system and marked as up.  If multiple
  interfaces are present, routed assumes that the local	host forwards packets
  between networks.  The routed	daemon transmits an RIP	request	packet on
  each interface (using	a broadcast packet if the interface supports it) and
  then enters a	loop, listening	for RIP	routing	requests and response packets
  from other hosts. In addition, if routed is to supply	RIP information	to
  other	hosts, it periodically sends RIP update	packets	(containing copies of
  its routing tables) to any directly connected	hosts and networks.

  When routed receives a RIP request packet and	can supply RIP routing infor-
  mation, (the -s option is set), it generates a reply (response packet)
  based	on the information maintained in the kernel routing tables.  The
  response packet contains a list of known routes, each	marked with a hop
  count	metric (the number of host-to-host connections in the route). The
  metric for each route	is relative to the sending host. A metric of 16	or
  greater is considered	to be infinite,	or beyond reach.

  Updating Routing Tables


  If RIP processing is enabled,	routed uses information	contained in the RIP
  response and update packets from other hosts to update its routing tables.
  However, routed uses the information in the RIP routing packet to update
  the tables only if at	least one of the following conditions exists:

    +  No routing table	entry exists for the destination network or host, and
       the metric associated with the route is finite (that is,	the metric is
       less than 16).

    +  The source host of the packet is	the router in the existing routing
       table entry.

    +  The routing table entry is old and the new information is about a
       route that is at	least as efficient as the existing route.

    +  The new route is	shorter	than the one that is currently stored in the
       routing tables.	(Note that routed determines relative route length by
       comparing the new metric	with the one stored in the routing table.)

  When routed updates its internal routing tables, it generates	an RIP update
  packet to all	directly connected hosts and networks.	Before updating	the
  kernel routing tables, routed	pauses for a brief period to allow any
  unstable conditions to stabilize.

  Besides processing incoming RIP packets, routed also checks the internal
  routing table	entries	periodically.  The metric for any entry	that has not
  been updated for 3 minutes is	set to infinity	and marked for deletion.  The
  deletion is delayed for 60 seconds so	that information about the invali-
  dated	route can be distributed throughout the	network.  A host that acts as
  an RIP router	supplies its routing tables to all directly connected hosts
  and networks every 30	seconds.

  Using	Gateways


  In addition to managing routes to directly connected hosts and networks,
  routed maintains information about distant and external gateways.  At
  startup, routed reads	the /etc/gateways file to learn	about these gateways.

  The /etc/gateways file contains information about routes through distant
  and external gateways	to hosts and networks that can be advertised through
  RIP. These routes are	either static routes to	specific destinations, or
  default routes that apply when a static route	to a destination is unspeci-
  fied.

  Gateways that	supply RIP routing information are marked active in the
  /etc/gateways	file. The routed daemons distributes RIP routing information
  to active gateways; if no RIP	routing	information is received	from the
  gateway for a	period of time,	routed deletes the associated route from the
  routing tables.

  Gateways that	do not exchange	RIP routing information	are marked passive in
  the /etc/gateways file. The routed daemon maintains information about
  passive gateways indefinitely, and includes information about	them in	any
  RIP routing information transmitted.

  Gateways are identified as external to inform	routed that another routing
  process installs the route.

  Information about external gateways is not maintained	in the routing
  tables.  Note	that routes through external gateways must be to networks
  only.

  If a logfile is specified, routed writes information about its actions to
  the specified	log file.  The log contains information	about any changes to
  the routing tables and a history of recent route change messages sent	and
  received that	are related to changed routes.

  Signals


  The following	signals	have the specified effect when sent to the routed
  process using	the kill(1) command:

  SIGUSR1
      Displays internal	routing	tables.

  SIGHUP, SIGTERM, or SIGQUIT
      Broadcasts RIP packets with hop counts set to infinity. Essentially,
      these signals disable the	local host as a	router.	 On a second SIGHUP,
      SIGTERM, or SIGQUIT, routed terminates.

RESTRICTIONS

   1.  The gated and routed daemons should not both be run on the same host,
       as this may produce unpredictable results.

   2.  Routes through external gateways	must be	to networks only.

FILES

  /usr/sbin/routed
      Specifies	the command path

  /etc/gateways
      Routes through distant and external gateways

  /etc/networks
      Contains the network name	database

SEE ALSO

  Commands: route(8)

  Daemons: gated(8)