191 lines
5.4 KiB
Groff
191 lines
5.4 KiB
Groff
.\" $OpenBSD: ospfd.8,v 1.34 2023/03/02 17:09:54 jmc Exp $
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.\"
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.\" Copyright (c) 2004, 2005, 2007 Esben Norby <norby@openbsd.org>
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.Dd $Mdocdate: March 2 2023 $
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.Dt OSPFD 8
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.Os
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.Sh NAME
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.Nm ospfd
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.Nd Open Shortest Path First (OSPF) routing daemon
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.Sh SYNOPSIS
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.Nm
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.Op Fl dnv
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.Op Fl D Ar macro Ns = Ns Ar value
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.Op Fl f Ar file
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.Op Fl s Ar socket
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.Sh DESCRIPTION
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.Nm
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is an Open Shortest Path First
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.Pq OSPF
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daemon which manages routing tables.
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This implementation supports OSPF version 2, thus it is only capable of
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maintaining IPv4 routing tables.
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.Pp
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OSPF is an interior gateway protocol designed to supersede RIP.
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It has several advantages over RIP.
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For instance, every router has an understanding of the complete network
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topology.
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Response to changes in the network is faster.
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Furthermore, failure detection is improved.
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.Pp
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The OSPF daemon maintains a Link State Database
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.Pq LSDB
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containing information about routers and networks within an Autonomous System
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.Pq AS .
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.Pp
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Dijkstra's shortest path first algorithm is used to compute a Routing
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Information Base
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.Pq RIB
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using the LSDB as input.
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The Forwarding Information Base
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.Pq FIB ,
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a.k.a. the kernel routing table, is updated with information from the RIB.
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.Pp
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OSPF routers discover one another automatically via OSPF hello packets.
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OSPF routers communicate via two multicast groups: 224.0.0.5 (all Shortest
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Path First routers) and 224.0.0.6 (all Designated Routers).
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OSPF runs directly on top of IP and uses neither TCP nor UDP.
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IP protocol number 89 is reserved for OSPF.
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.Pp
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All routers in an OSPF network spend most of their time keeping each others'
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LSDBs in sync.
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All routers must have the same information in the LSDB at all times.
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Every time the LSDB is updated, the RIB is updated; if needed, the FIB is
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also updated.
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.Pp
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In a multi-access network such as Ethernet, it is unfeasible for all routers
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to synchronize their LSDB with all other routers in the network.
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In such networks a Designated Router
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.Pq DR
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and a Backup Designated Router
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.Pq BDR
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are elected.
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The DR's responsibility is to synchronize with all routers; the BDR will
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not do much until the DR fails.
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The first router in a network is automatically elected DR, the second
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router BDR.
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All routers have a FULL adjacency with the DR and the BDR.
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Routers with FULL adjacency exchange information about their LSDBs.
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A router not elected either DR or BDR will have 2-WAY adjacency with all
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routers but the DR and BDR.
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Routers with 2-WAY adjacency recognize that they know each other,
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but do not exchange information about their LSDBs.
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If a DR or BDR fails, another router is elected DR or BDR
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and all routers form FULL adjacencies with the newly elected DR or BDR.
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.Pp
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When routers are connected via point-to-point links, DR and BDR
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election is skipped since only two routers are connected to the link.
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.Pp
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To limit the impact changes in the network have on the LSDB it is possible
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to segment an OSPF network into areas.
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Area 0.0.0.0 (a.k.a. the backbone area) must always be present.
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Routers can be configured as Area Border Router
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.Pq ABR ,
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being part of multiple areas.
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Every area must have direct access to the backbone area.
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ABRs not directly connected to the backbone area need to establish a
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virtual link to a router in the backbone area.
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.Pp
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AS Border Routers
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.Pq ASBR
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are connected to an OSPF network and other external networks via BGP, RIP,
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or static routing, and provide connectivity to networks outside the AS.
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.Pp
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To have
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.Nm
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enabled at boot time, use
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.Dq rcctl enable ospfd ,
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which sets
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.Pp
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.Dl ospfd_flags=\(dq\(dq
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.Pp
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in
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.Xr rc.conf.local 8 .
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.Pp
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A running
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.Nm
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can be controlled with the
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.Xr ospfctl 8
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utility.
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.Pp
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The options are as follows:
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.Bl -tag -width Ds
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.It Fl D Ar macro Ns = Ns Ar value
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Define
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.Ar macro
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to be set to
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.Ar value
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on the command line.
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Overrides the definition of
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.Ar macro
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in the configuration file.
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.It Fl d
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Do not daemonize.
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If this option is specified,
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.Nm
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will run in the foreground and log to
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.Em stderr .
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.It Fl f Ar file
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Specify an alternative configuration file.
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.It Fl n
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Configtest mode.
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Only check the configuration file for validity.
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.It Fl s Ar socket
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Use an alternate location for the default control socket.
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.It Fl v
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Produce more verbose output.
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.El
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.Sh FILES
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.Bl -tag -width "/var/run/ospfd.sockXX" -compact
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.It Pa /etc/ospfd.conf
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Default
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.Nm
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configuration file.
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.It Pa /var/run/ospfd.sock
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.Ux Ns -domain
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socket used for communication with
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.Xr ospfctl 8 .
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.El
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.Sh SEE ALSO
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.Xr ospfd.conf 5 ,
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.Xr ospfctl 8
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.Sh STANDARDS
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.Rs
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.%A J. Moy
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.%D April 1998
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.%R RFC 2328
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.%T OSPF Version 2
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.Re
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.Pp
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.Rs
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.%A A. Retana
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.%A L. Nguyen
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.%A R. White
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.%A A. Zinin
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.%A D. McPherson
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.%D June 2001
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.%R RFC 3137
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.%T OSPF Stub Router Advertisement
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.Re
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.Sh HISTORY
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The
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.Nm
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program first appeared in
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.Ox 3.7 .
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.Sh BUGS
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Virtual links are currently not available in
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.Nm .
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