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MROUTED(8)           FreeBSD System Manager's Manual (smm)          MROUTED(8)

     mrouted - IP multicast routing daemon

     mrouted [-fhp] [-c FILE] [-d [[LEVEL[,LEVEL,...]]]

     mrouted is an implementation of the Distance-Vector Multicast Routing
     Protocol (DVMRP), an earlier version of which is specified in RFC 1075.
     It maintains topological knowledge via a distance-vector routing protocol
     (like RIP, described in RFC 1058), upon which it implements a multicast
     datagram forwarding algorithm called Reverse Path Multicasting.

     mrouted forwards a multicast datagram along a shortest (reverse) path
     tree rooted at the subnet on which the datagram originates.  The
     multicast delivery tree may be thought of as a broadcast delivery tree
     that has been pruned back so that it does not extend beyond those
     subnetworks that have members of the destination group.  Hence, datagrams
     are not forwarded along those branches which have no listeners of the
     multicast group.  The IP time-to-live of a multicast datagram can be used
     to limit the range of multicast datagrams.

     In order to support multicasting among subnets that are separated by
     (unicast) routers that do not support IP multicasting, mrouted includes
     support for "tunnels", which are virtual point-to-point links between
     pairs of mrouted daemons located anywhere in an internet.  IP multicast
     packets are encapsulated for transmission through tunnels, so that they
     look like normal unicast datagrams to intervening routers and subnets.
     The encapsulation is added on entry to a tunnel, and stripped off on exit
     from a tunnel.  By default, the packets are encapsulated using the IP-in-
     IP protocol (IP protocol number 4).  Older versions of mrouted tunnel use
     IP source routing, which puts a heavy load on some types of routers.
     This version does not support IP source route tunnelling.

     The tunnelling mechanism allows mrouted to establish a virtual internet,
     for the purpose of multicasting only, which is independent of the
     physical internet, and which may span multiple Autonomous Systems.  This
     capability is intended for experimental support of internet multicasting
     only, pending widespread support for multicast routing by the regular
     (unicast) routers.  mrouted suffers from the well-known scaling problems
     of any distance-vector routing protocol, and does not (yet) support
     hierarchical multicast routing.

     mrouted handles multicast routing only; there may or may not be unicast
     routing software running on the same machine as mrouted.  With the use of
     tunnels, it is not necessary for mrouted to have access to more than one
     physical subnet in order to perform multicast forwarding.

     This program follows the usual UNIX command line syntax, with long
     options starting with two dashes (`-').  The options are as follows:

     -h, --help
             Print a help message and exit.

     -M, --missing-ok
             If an interface does not yet exist, print a warning and continue.
             Useful with VPN and other dynamic interfaces.  However, mrouted
             must be restarted to start listening on such interfaces, if they
             did not exist when mrouted was started.

     -N, --no-interfaces
             Assume all interfaces are disabled unless explicitly enabled with
             phyint enable

     -f, --foreground
             Run in foreground, do not detach from the calling terminal.

     -c, --config=FILE
             Specify an alternative configuration file, default

     -d, --debug[=LEVEL[,LEVEL...]
             By default, mrouted detaches from the invoking terminal.  If this
             option is specified, mrouted it runs in foreground of the
             starting terminal and responds to signals.  If -d is given with
             no argument, the debug level defaults to igmp, cache, interface,
             groups, prunes, routes and peers.

             Regardless of the debug level, mrouted always writes warning and
             error messages to the system log daemon.  Debug levels have the
             following effects:

                         Debug inbound/outbout packets
                         Pruning operations, or pruned routes
                         Routing messages
                         Detailed routing information
                         Neighbor gossip
                         Debug routing cache
                         Debug timeouts
                         Show interface, or vif, debug messages
                         Debug group memberships
                         Multicast traceroute information
                   igmp  Debug IGMP messages
                   icmp  Debug ICMP messages
                   rsrr  Debug RSRR messages

     -p      Start mrouted in a non-pruning mode.  This was previously used in
             routers for test purposes only.  However, this is no longer
             supported and this option is only kept for compatibility reasons.

     -r, --show-routes
             Show state of VIFs and multicast routing tables. This command
             sends SIGUSR1 to a running mrouted, waits for the dump file to be
             updated, and then displays the result on stdout.

     mrouted automatically configures itself to forward on all multicast-
     capable interfaces, i.e. interfaces that have the IFF_MULTICAST flag set
     (excluding the loopback "interface"), and it finds other mrouted directly
     reachable via those interfaces.  To override the default configuration,
     or to add tunnel links to other mrouted, configuration commands may be
     placed in /etc/mrouted.conf.  There are five types of configuration

           cache_lifetime _SEC_

           name boundary-name | scoped-addr/mask-len

           phyint local-addr [altnet network/mask-len] [boundary boundary-name
           | scoped-addr/mask-len]
           [disable | enable]
           [metric _1-31_]
           [rate_limit kbps]
           [threshold ttl]

           pruning [off | on]

           tunnel local-addr remote-addr [boundary boundary-name |
           [metric _1-31_]
           [rate_limit kbps]
           [threshold ttl]

     The file format is free-form: whitespace (including newlines) is not
     significant.  The boundary option can accept either a name or a boundary;
     the boundary and altnet options may be specified as many times as

     The cache_lifetime is a value that determines the amount of time that a
     cached multicast route stays in kernel before timing out.  The value of
     this entry should lie between 300 (5 min) and 86400 (1 day).  It defaults
     to 300.

     The name option assigns names to boundaries to make configuration easier.

     The phyint command can be used to disable multicast routing on the
     physical interface identified by local IP address local-addr, or to
     associate a non-default metric or threshold with the specified physical
     interface.  The local IP address local-addr may be replaced by the
     interface name (e.g. le0).  If a phyint is attached to multiple IP
     subnets, describe each additional subnet with the altnet keyword.  Phyint
     commands must precede tunnel commands.

     The pruning option is provided for mrouted to act as a non-pruning
     router.  This is no longer supported and the configuration option is only
     kept for compatibility reasons.

     The tunnel command can be used to establish a tunnel link between local
     IP address local-addr and remote IP address remote-addr, and to associate
     a non-default metric or threshold with that tunnel.  The local IP address
     local-addr may be replaced by the interface name (e.g. le0).  The remote
     IP address remote-addr may be replaced by a host name, if and only if the
     host name has a single IP address associated with it.  The tunnel must be
     set up in the mrouted.conf files of both routers before it can be used.

     boundary allows an interface to be configured as an administrative
     boundary for the specified scoped address.  Packets belonging to this
     address will not be forwarded on a scoped interface.  The boundary option
     accepts either a name or a boundary spec.

     metric is the "cost" associated with sending a datagram on the given
     interface or tunnel; it may be used to influence the choice of routes.
     The metric defaults to 1.  Metrics should be kept as small as possible,
     because mrouted cannot route along paths with a sum of metrics greater
     than 31.

     rate_limit allows the network administrator to specify a certain
     bandwidth in kbps which would be allocated to multicast traffic.  It
     defaults to 500 kbps on tunnels, and 0 (unlimited) on physical

     threshold is the minimum IP time-to-live required for a multicast
     datagram to be forwarded to the given interface or tunnel.  It is used to
     control the scope of multicast datagrams.  (The TTL of forwarded packets
     is only compared to the threshold, it is not decremented by the
     threshold.  Every multicast router decrements the TTL by 1.)  The default
     threshold is 1.

     In general, all mrouted connected to a particular subnet or tunnel should
     use the same metric and threshold for that subnet or tunnel.

     mrouted will not initiate execution if it has fewer than two enabled
     virtual interfaces (vifs), where a vif is either a physical multicast-
     capable interface or a tunnel.  It will log a warning if all of its vifs
     are tunnels; such an mrouted configuration would be better replaced by
     more direct tunnels (i.e. eliminate the middle man).

     This is an example configuration for a mythical multicast router at a big

     # mrouted.conf example

     # Name our boundaries to make it easier.
     name LOCAL
     name EE

     # le1 is our gateway to compsci, don't forward our
     # local groups to them.
     phyint le1 boundary EE

     # le2 is our interface on the classroom net, it has four
     # different length subnets on it.
     # Note that you can use either an IP address or an interface name
     phyint boundary EE

     # atm0 is our ATM interface, which doesn't properly
     # support multicasting.
     phyint atm0 disable

     # This is an internal tunnel to another EE subnet.
     # Remove the default tunnel rate limit, since this
     # tunnel is over Ethernets.
            metric 1 threshold 1 rate_limit 0

     # This is our tunnel to the outside world.
     # Careful with those boundaries, Eugene.
            metric 1 threshold 32
            boundary LOCAL boundary EE

     mrouted responds to the following signals:

     HUP   Restarts mrouted.  The configuration file is reread when SIGHUP is
     INT   Terminates execution gracefully (i.e. by sending good-bye messages
           to all neighboring routers).
     TERM  The same as INT.
     USR1  Dumps the internal routing tables to /var/run/mrouted/mrouted.dump.
     USR2  Dumps the internal cache tables to /var/run/mrouted/mrouted.cache.
     QUIT  Dumps the internal routing tables to stderr (only if mrouted was
           invoked with a non-zero debug level).

     For convenience in sending signals, mrouted writes its process ID to
     /var/run/ upon startup.


     The routing tables look like this:

     Virtual Interface Table
      Vif  Local-Address                    Metric  Thresh  Flags
       0      subnet: 36.2          1       1    querier
                        pkts in: 3456
                       pkts out: 2322323

       1     subnet: 36.11         1       1    querier
                        pkts in: 345
                       pkts out: 3456

       2      tunnel:     3       1
                          peers: (2.2)
                     boundaries: 239.0.1
                               : 239.1.2
                        pkts in: 34545433
                       pkts out: 234342

       3     tunnel:      3       16

     Multicast Routing Table (1136 entries)
      Origin-Subnet   From-Gateway    Metric Tmr In-Vif  Out-Vifs
      36.2                               1    45    0    1* 2  3*
      36.8            4    15    2    0* 1* 3*
      36.11                              1    20    1    0* 2  3*

     In this example, there are four vifs connecting to two subnets and two
     tunnels.  The vif 3 tunnel is not in use (no peer address).  The vif 0
     and vif 1 subnets have some groups present; tunnels never have any
     groups.  This instance of mrouted is the one responsible for sending
     periodic group membership queries on the vif 0 and vif 1 subnets, as
     indicated by the "querier" flags.  The list of boundaries indicate the
     scoped addresses on that interface.  A count of the number of incoming
     and outgoing packets is also shown at each interface.

     Associated with each subnet from which a multicast datagram can originate
     is the address of the previous hop router (unless the subnet is directly-
     connected), the metric of the path back to the origin, the amount of time
     since we last received an update for this subnet, the incoming vif for
     multicasts from that origin, and a list of outgoing vifs.  "*" means that
     the outgoing vif is connected to a leaf of the broadcast tree rooted at
     the origin, and a multicast datagram from that origin will be forwarded
     on that outgoing vif only if there are members of the destination group
     on that leaf.

     mrouted also maintains a copy of the kernel forwarding cache table.
     Entries are created and deleted by mrouted.

     The cache tables look like this:

     Multicast Routing Cache Table (147 entries)
      Origin             Mcast-group     CTmr  Age Ptmr IVif Forwvifs
      13.2.116/22     3m   2m    -  0    1
      138.96.48/21     5m   2m    -  0    1
      128.9.160/20     3m   2m    -  0    1
      198.106.194/24     9m  28s   9m  0P

     Each entry is characterized by the origin subnet number and mask and the
     destination multicast group.

     The 'CTmr' field indicates the lifetime of the entry.  The entry is
     deleted from the cache table when the timer decrements to zero.  The
     'Age' field is the time since this cache entry was originally created.
     Since cache entries get refreshed if traffic is flowing, routing entries
     can grow very old.

     The 'Ptmr' field is simply a dash if no prune was sent upstream, or the
     amount of time until the upstream prune will time out.  The 'Ivif' field
     indicates the incoming vif for multicast packets from that origin.

     Each router also maintains a record of the number of prunes received from
     neighboring routers for a particular source and group.

     If there are no members of a multicast group on any downward link of the
     multicast tree for a subnet, a prune message is sent to the upstream
     router.  They are indicated by a "P" after the vif number.

     The Forwvifs field shows the interfaces along which datagrams belonging
     to the source-group are forwarded.

     A "p" indicates that no datagrams are being forwarded along that
     interface.  An unlisted interface is a leaf subnet with no members of the
     particular group on that subnet.

     A "b" on an interface indicates that it is a boundary interface, i.e.
     traffic will not be forwarded on the scoped address on that interface.
     An additional line with a `>' as the first character is printed for each
     source on the subnet.

     Note that there can be many sources in one subnet.

     map-mbone(8), mrinfo(8), mtrace(8), pimd(8)

     S. Deering, Multicast Routing in Internetworks and Extended LANs,
     Proceedings of the ACM SIGCOMM '88 Conference.

     David Waitzman, Craig Partridge, Steve Deering, Ajit Thyagarajan, Bill
     Fenner, David Thaler, and Daniel Zappala.  With contributions by many

FreeBSD 11.0-PRERELEASE        January 17, 2013        FreeBSD 11.0-PRERELEASE


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