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NG_ONE2MANY(4)         FreeBSD Kernel Interfaces Manual         NG_ONE2MANY(4)

NAME
     ng_one2many - packet multiplexing netgraph node type

SYNOPSIS
     #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 of the many hooks; which hook is determined by the
     node's configured 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.

TRANSMIT ALGORITHMS
     At this time, the only algorithm for determing the outgoing many hook is
     a simple round-robin delivery algorithm.  Packets are delivered out the
     many hooks in sequential order.

     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:

          /* Node configuration structure */
          struct ng_one2many_config {
            u_int32_t   xmitAlg;        /* how to distribute packets */
            u_int32_t   failAlg;        /* how to detect link failure */
            u_char      enabledLinks[NG_ONE2MANY_MAX_LINKS];
          };

          Currently, the only valid setting for the xmitAlg field is
          NG_ONE2MANY_XMIT_ROUNDROBIN; this is also the default setting.  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
          corresponding 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
          statistics 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
     networking 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.

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), ngctl(8)

HISTORY
     The ng_one2many node type was implemented in FreeBSD 4.2.

AUTHORS
     Archie Cobbs <archie@FreeBSD.org>

FreeBSD 11.0-PRERELEASE        November 15, 2000       FreeBSD 11.0-PRERELEASE

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

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