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 forward
ed out one or
more of the many hooks; which hook(s) 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.
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

The node distinguishes between active and failed links. Da
ta 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
considers link failed if NGM_LINK_IS_DOWN is re
ceived. 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
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 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
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 correspond
ing 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.

SEE ALSO

netgraph(4), ng_bridge(4), ng_ether(4), ng_hub(4), ifcon
fig(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 support
ed. A good
candidate is Cisco's Etherchannel.
BSD February 19, 2006
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