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NG_ONE2MANY(4)	       FreeBSD 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)	fash-
     ion.  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 config-
     ured transmit algorithm.  Packets are not altered in any way.

     Each of the connected many	links may be considered	to be up or down.
     Packets are never delivered out a many hook that is down.	How a link is
     determined	to be up or down depends on the	node's configured link failure
     detection 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 con-
	  nected links are down	until configured otherwise.

     NG_ONE2MANY_FAIL_NOTIFY
	  The node listens to flow control message from	many hooks, and	con-
	  siders 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
     message 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 sta-
	  tistics 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 net-
     working 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
     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
     candidate is Cisco's Etherchannel.

FreeBSD	10.1		       November	13, 2012		  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | TRANSMIT ALGORITHMS | LINK FAILURE DETECTION | HOOKS | CONTROL MESSAGES | SHUTDOWN | EXAMPLES | SEE ALSO | HISTORY | AUTHORS | BUGS

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