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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.

     In the future other algorithms may be added as well.

LINK FAILURE DETECTION

     At this time, the only algorithm for determining when a link has failed,
     other than the hook being disconnected, is the ``manual'' algorithm: 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.

     In the future other algorithms may be added as well.

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
	  Sets the node configuration using a struct ng_one2many_link_config
	  as the control message argument:

	  NG_ONE2MANY_XMIT_ROUNDROBIN (default) or NG_ONE2MANY_XMIT_ALL.  The
	  only valid setting for failAlg is NG_ONE2MANY_FAIL_MANUAL; this is
	  also the default setting.

     NGM_ONE2MANY_GET_CONFIG
	  Returns the current node configuration in a struct
	  ng_one2many_link_config.

     NGM_ONE2MANY_GET_STATS
	  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 {
	    u_int64_t	recvOctets;	/* total octets rec'd on link */
	    u_int64_t	recvPackets;	/* total pkts rec'd on link */
	    u_int64_t	xmitOctets;	/* total octets xmit'd on link */
	    u_int64_t	xmitPackets;	/* total pkts xmit'd on link */
	  };

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

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

     NGM_ONE2MANY_GETCLR_STATS
	  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

     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.

BUGS

     More transmit and link failure algorithms should be supported.  A good
     candidate is Cisco's Etherchannel.

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>.

FreeBSD 5.4		       January 26, 2001 		   FreeBSD 5.4

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