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OSPFD(8)		FreeBSD	System Manager's Manual		      OSPFD(8)

     ospfd -- Open Shortest Path First daemon

     ospfd [-dnv] [-D macro=value] [-f file] [-s socket]

     ospfd is an Open Shortest Path First (OSPF) daemon	which manages routing
     tables.  This implementation supports OSPF	version	2, thus	it is only ca-
     pable of maintaining IPv4 routing tables.

     OSPF is an	interior gateway protocol designed to supersede	RIP.  It has
     several advantages	over RIP.  For instance, every router has an under-
     standing of the complete network topology.	 Response to changes in	the
     network is	faster.	 Furthermore, failure detection	is improved.

     The OSPF daemon maintains a Link State Database (LSDB) containing infor-
     mation about routers and networks within an Autonomous System (AS).

     Dijkstra's	shortest path first algorithm is used to compute a Routing In-
     formation Base (RIB) using	the LSDB as input.  The	Forwarding Information
     Base (FIB), a.k.a.	the kernel routing table, is updated with information
     from the RIB.

     OSPF routers discover one another automatically via OSPF hello packets.
     OSPF routers communicate via two multicast	groups: (all Short-
     est Path First routers) and (all	Designated Routers).  OSPF
     runs directly on top of IP	and uses neither TCP nor UDP.  IP protocol
     number 89 is reserved for OSPF.

     All routers in an OSPF network spend most of their	time keeping each oth-
     ers' LSDBs	in sync.  All routers must have	the same information in	the
     LSDB at all times.	 Every time the	LSDB is	updated	the RIB	is updated; if
     needed the	FIB is also updated.

     In	a multi-access network such as Ethernet, it is unfeasible for all
     routers to	synchronize their LSDB with all	other routers in the network.
     In	such networks a	Designated Router (DR) and a Backup Designated Router
     (BDR) are elected.	 The DR's responsibility is to synchronize with	all
     routers; the BDR will not do much until the DR fails.  The	first router
     in	a network is automatically elected DR, the second router BDR.  All
     routers have a FULL adjacency with	the DR and the BDR.  Routers with FULL
     adjacency exchange	information about their	LSDBs.	A router not elected
     either DR or BDR will have	2-WAY adjacency	with all routers but the DR
     and BDR.  Routers with 2-WAY adjacency recognize that they	know each
     other, but	do not exchange	information about their	LSDBs.	If a DR	or BDR
     fails another router is elected DR	or BDR and all routers form FULL adja-
     cencies with the newly elected DR or BDR.

     When routers are connected	via point-to-point links, DR and BDR election
     is	skipped	since only two routers are connected to	the link.

     To	limit the impact changes in the	network	have on	the LSDB it is possi-
     ble to segment an OSPF network into areas.	 Area (a.k.a. the
     backbone area) must always	be present.  Routers can be configured as Area
     Border Router (ABR), being	part of	multiple areas.	 Every area must have
     direct access to the backbone area.  ABRs not directly connected to the
     backbone area need	to establish a virtual link to a router	in the back-
     bone area.

     AS	Border Routers (ASBR) are connected to an OSPF network and other ex-
     ternal networks via BGP, RIP, or static routing, and provide connectivity
     to	networks outside the AS.

     To	have ospfd enabled at boot time, use "rcctl enable ospfd", which sets


     in	rc.conf.local(8).

     A running ospfd can be controlled with the	ospfctl(8) utility.

     The options are as	follows:

     -D	macro=value
	     Define macro to be	set to value on	the command line.  Overrides
	     the definition of macro in	the configuration file.

     -d	     Do	not daemonize.	If this	option is specified, ospfd will	run in
	     the foreground and	log to stderr.

     -f	file
	     Specify an	alternative configuration file.

     -n	     Configtest	mode.  Only check the configuration file for validity.

     -s	socket
	     Use an alternate location for the default control socket.

     -v	     Produce more verbose output.

     /etc/ospfd.conf	    Default ospfd configuration	file.
     /var/run/ospfd.sock    UNIX-domain	socket used for	communication with

     ospfd.conf(5), ospfctl(8)

     J.	Moy, OSPF Version 2, RFC 2328, April 1998.

     A.	Retana,	L. Nguyen, R. White, A.	Zinin, and D. McPherson, OSPF Stub
     Router Advertisement, RFC 3137, June 2001.

     The ospfd program first appeared in OpenBSD 3.7.

     Virtual links are currently not available in ospfd.

FreeBSD	13.0		       November	10, 2019		  FreeBSD 13.0


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