man/man4/ng_one2many.4

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.\" Author: Archie Cobbs <archie@FreeBSD.org>
.\"
.\" $FreeBSD$
.\"
.Dd February 19, 2006
.Dt NG_ONE2MANY 4
.Os
.Sh NAME
.Nm ng_one2many
.Nd packet multiplexing netgraph node type
.Sh SYNOPSIS
.In sys/types.h
.In netgraph/ng_one2many.h
.Sh DESCRIPTION
The
.Nm 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
.Dv one ,
and multiple hooks named
.Dv many0 ,
.Dv many1 ,
etc.
Packets received on any of the
.Dv many
hooks are forwarded out the
.Dv one
hook.
Packets received on the
.Dv one
hook are forwarded out one or more of the
.Dv many
hooks; which hook(s) is determined by the node's configured
transmit algorithm.
Packets are not altered in any way.
.Pp
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.
.Pp
Before an interface or link can be plumbed into a group, its status
must be marked as being
.Dq up .
This is normally setup during the initial boot stages by
.Xr rc.conf 5 .
It is also possible to change an interface's status to
.Dq up
by using the
.Xr ifconfig 8
utility.
.Sh TRANSMIT ALGORITHMS
.Bl -tag -width foo
.It Dv NG_ONE2MANY_XMIT_ROUNDROBIN
Packets are delivered out the many hooks in sequential order.
Each packet goes out on a different
.Dv many
hook.
.It Dv NG_ONE2MANY_XMIT_ALL
Packets are delivered out all the
.Dv many
hooks.
Each packet goes out each
.Dv many
hook.
.El
.Pp
In the future other algorithms may be added as well.
.Sh 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:
.Bl -tag -width indent
.It Dv NG_ONE2MANY_FAIL_MANUAL
The node is explicitly told which of the links are up via the
.Dv NGM_ONE2MANY_SET_CONFIG
control message (see below).
Newly connected links are down until configured otherwise.
.It Dv NG_ONE2MANY_FAIL_NOTIFY
The node listens to flow control message from
.Va many
hooks, and considers link failed if
.Dv NGM_LINK_IS_DOWN
is received.
If the
.Dv NGM_LINK_IS_UP
message is received, node considers link active.
.El
.Pp
In the future other algorithms may be added as well.
.Pp
When all links are considered failed, node sends the
.Dv NGM_LINK_IS_DOWN
message towards the
.Va one
hook.
When at least one link comes up, node sends the
.Dv NGM_LINK_IS_UP
message towards the
.Va one
hook.
.Sh HOOKS
This node type supports up to
.Dv NG_ONE2MANY_MAX_LINKS
hooks named
.Dv many0 ,
.Dv many1 ,
etc.,
plus a single hook named
.Dv one .
.Sh CONTROL MESSAGES
This node type supports the generic control messages, plus the
following:
.Bl -tag -width foo
.It Dv NGM_ONE2MANY_SET_CONFIG
Sets the node configuration using a
.Dv "struct ng_one2many_link_config"
as the control message argument:
.Bd -literal
/* 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];
};
.Ed
.Pp
Currently, the valid settings for the
.Dv xmitAlg
field are
.Dv NG_ONE2MANY_XMIT_ROUNDROBIN
(default) or
.Dv NG_ONE2MANY_XMIT_ALL .
The valid settings for
.Dv failAlg
are
.Dv NG_ONE2MANY_FAIL_MANUAL
(default) or
.Dv NG_ONE2MANY_FAIL_NOTIFY .
.It Dv NGM_ONE2MANY_GET_CONFIG
Returns the current node configuration in a
.Dv "struct ng_one2many_link_config" .
.It Dv NGM_ONE2MANY_GET_STATS
This command takes a 32 bit link number as an argument and
returns a
.Dv "struct ng_one2many_link_stats"
containing statistics for the corresponding
.Dv many
link, which may or may not be currently connected:
.Bd -literal
/* 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 */
};
.Ed
.Pp
To access statistics for the
.Dv one
link, use the link number
.Dv -1 .
.It Dv NGM_ONE2MANY_CLR_STATS
This command takes a 32 bit link number as an argument and
clears the statistics for that link.
.It Dv NGM_ONE2MANY_GETCLR_STATS
Same as
.Dv NGM_ONE2MANY_GET_STATS ,
but also atomically clears the statistics for the link as well.
.El
.Sh SHUTDOWN
This node shuts down upon receipt of a
.Dv NGM_SHUTDOWN
control message, or when all hooks have been disconnected.
.Sh EXAMPLES
The following commands will set up Ethernet interfaces
.Dv fxp0
to deliver packets alternating over the physical interfaces
corresponding to networking interfaces
.Dv fxp0
through
.Dv fxp3 :
.Bd -literal
  # 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
.Ed
.Pp
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.
.Sh SEE ALSO
.Xr netgraph 4 ,
.Xr ng_bridge 4 ,
.Xr ng_ether 4 ,
.Xr ng_hub 4 ,
.Xr ifconfig 8 ,
.Xr ngctl 8
.Sh HISTORY
The
.Nm
node type was implemented in
.Fx 4.2 .
.Sh AUTHORS
.An -nosplit
The
.Nm one2many
netgraph node (with round-robin algorithm) was written by
.An Archie Cobbs
.Aq archie@FreeBSD.org .
The all algorithm was added by
.An Rogier R. Mulhuijzen
.Aq drwilco@drwilco.net .
.Sh BUGS
More transmit and link failure algorithms should be supported.
A good candidate is Cisco's Etherchannel.