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NG_ONE2MANY(4)		     Kernel Interfaces Manual		  NG_ONE2MANY(4)

NAME
     ng_one2many -- packet multiplexing netgraph node type

SYNOPSIS
     #include <sys/types.h>
     #include <netgraph/ng_one2many.h>

DESCRIPTION
     The  one2many  provides a simple mechanism for routing packets over several
     links in a one-to-many (and in the reverse direction, many-to-one) fashion.
     There is a single hook named one, and multiple hooks  named  many0,  many1,
     etc.   Packets  received on any of the many hooks are forwarded out the one
     hook.  Packets received on the one hook are forwarded out one  or	more  of
     the many hooks; which hook(s) is determined by the node's configured trans-
     mit algorithm.  Packets are not altered in any way.

     Each of the connected many links may be considered to be up or down.  Pack-
     ets are never delivered out a many hook that is down.  How a link is deter-
     mined to be up or down depends on the node's configured link failure detec-
     tion algorithm.

     Before an interface or link can be plumbed into a group, its status must be
     marked  as  being	"up".	This  is  normally setup during the initial boot
     stages by rc.conf(5).  It is also possible to change an interface's  status
     to "up" by using the ifconfig(8) utility.

TRANSMIT ALGORITHMS
     NG_ONE2MANY_XMIT_ROUNDROBIN
	  Packets  are	delivered  out the many hooks in sequential order.  Each
	  packet goes out on a different many hook.

     NG_ONE2MANY_XMIT_ALL
	  Packets are delivered out all the many hooks.  Each  packet  goes  out
	  each many hook.

     NG_ONE2MANY_XMIT_FAILOVER
	  Packets are delivered out the first active many hook.

     In the future other algorithms may be added as well.

LINK FAILURE DETECTION
     The  node distinguishes between active and failed links.  Data is sent only
     to active links.  The  following  link  failure  detection  algorithms  are
     available:

     NG_ONE2MANY_FAIL_MANUAL
	  The  node  is  explicitly  told  which  of  the  links  are up via the
	  NGM_ONE2MANY_SET_CONFIG control message (see below).	Newly  connected
	  links are down until configured otherwise.

     NG_ONE2MANY_FAIL_NOTIFY
	  The  node listens to flow control message from many hooks, and consid-
	  ers  link  failed   if   NGM_LINK_IS_DOWN   is   received.	If   the
	  NGM_LINK_IS_UP message is received, node considers link active.

     In the future other algorithms may be added as well.

     When  all links are considered failed, node sends the NGM_LINK_IS_DOWN mes-
     sage towards the one hook.  When at least one link comes up, node sends the
     NGM_LINK_IS_UP message towards the one hook.

HOOKS
     This node type supports up  to  NG_ONE2MANY_MAX_LINKS  hooks  named  many0,
     many1, etc., plus a single hook named one.

CONTROL MESSAGES
     This node type supports the generic control messages, plus the following:

     NGM_ONE2MANY_SET_CONFIG (setconfig)
	  Sets	the node configuration using a struct ng_one2many_link_config as
	  the control message argument:

	  /* Node configuration structure */
	  struct ng_one2many_config {
	    uint32_t	xmitAlg;	/* how to distribute packets */
	    uint32_t	failAlg;	/* how to detect link failure */
	    u_char	enabledLinks[NG_ONE2MANY_MAX_LINKS];
	  };

	  Currently,  the   valid   settings   for   the   xmitAlg   field   are
	  NG_ONE2MANY_XMIT_ROUNDROBIN  (default)  or  NG_ONE2MANY_XMIT_ALL.  The
	  valid settings for failAlg are  NG_ONE2MANY_FAIL_MANUAL  (default)  or
	  NG_ONE2MANY_FAIL_NOTIFY.

     NGM_ONE2MANY_GET_CONFIG (getconfig)
	  Returns    the    current    node    configuration	in    a   struct
	  ng_one2many_link_config.

     NGM_ONE2MANY_GET_STATS (getstats)
	  This command takes a 32 bit link number as an argument and  returns  a
	  struct  ng_one2many_link_stats  containing  statistics  for the corre-
	  sponding many link, which may or may not be currently connected:

	  /* Statistics structure (one for each link) */
	  struct ng_one2many_link_stats {
	    uint64_t   recvOctets;     /* total octets rec'd on link */
	    uint64_t   recvPackets;    /* total pkts rec'd on link */
	    uint64_t   xmitOctets;     /* total octets xmit'd on link */
	    uint64_t   xmitPackets;    /* total pkts xmit'd on link */
	    uint64_t   memoryFailures; /* times couldn't get mem or mbuf */
	  };

	  To access statistics for the one link, use the link number -1.

     NGM_ONE2MANY_CLR_STATS (clrstats)
	  This command takes a 32 bit link number as an argument and clears  the
	  statistics for that link.

     NGM_ONE2MANY_GETCLR_STATS (getclrstats)
	  Same as NGM_ONE2MANY_GET_STATS, but also atomically clears the statis-
	  tics for the link as well.

SHUTDOWN
     This  node  shuts	down  upon receipt of a NGM_SHUTDOWN control message, or
     when all hooks have been disconnected.

EXAMPLES
     The following commands will set up  Ethernet  interfaces  fxp0  to  deliver
     packets  alternating over the physical interfaces corresponding to network-
     ing interfaces fxp0 through fxp3:

       # Plumb nodes together

       ngctl mkpeer fxp0: one2many upper one
       ngctl connect fxp0: fxp0:upper lower many0
       ngctl connect fxp1: fxp0:upper lower many1
       ngctl connect fxp2: fxp0:upper lower many2
       ngctl connect fxp3: fxp0:upper lower many3

       # Allow fxp1 through fxp3 to xmit/recv fxp0 frames

       ngctl msg fxp1: setpromisc 1
       ngctl msg fxp2: setpromisc 1
       ngctl msg fxp3: setpromisc 1
       ngctl msg fxp1: setautosrc 0
       ngctl msg fxp2: setautosrc 0
       ngctl msg fxp3: setautosrc 0

       # Configure all four links as up

       ngctl msg fxp0:upper \
	 setconfig "{ xmitAlg=1 failAlg=1 enabledLinks=[ 1 1 1 1 ] }"

       # Bring up interface

       ifconfig fxp0 192.168.1.1 netmask 0xfffffffc

     With a similar setup on a peer machine (using the address	192.168.1.2),  a
     point-to-point  Ethernet  connection  with  four  times normal bandwidth is
     achieved.

SEE ALSO
     lagg(4), netgraph(4), ng_bridge(4),  ng_ether(4),	ng_hub(4),  ifconfig(8),
     ngctl(8)

HISTORY
     The ng_one2many node type was implemented in FreeBSD 4.2.

AUTHORS
     The  one2many  netgraph  node  (with  round-robin algorithm) was written by
     Archie Cobbs <archie@FreeBSD.org>.  The all algorithm was added  by  Rogier
     R. Mulhuijzen <drwilco@drwilco.net>.

BUGS
     More transmit and link failure algorithms should be supported.  A good can-
     didate is Cisco's Etherchannel.

FreeBSD ports 15.quarterly	November 13, 2012		  NG_ONE2MANY(4)

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