214 lines
7.7 KiB
Groff
214 lines
7.7 KiB
Groff
.\" Copyright (c) 2000 Whistle Communications, Inc.
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.\" All rights reserved.
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.\"
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.\" Subject to the following obligations and disclaimer of warranty, use and
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.\" redistribution of this software, in source or object code forms, with or
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.\" without modifications are expressly permitted by Whistle Communications;
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.\" provided, however, that:
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.\" 1. Any and all reproductions of the source or object code must include the
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.\" copyright notice above and the following disclaimer of warranties; and
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.\" 2. No rights are granted, in any manner or form, to use Whistle
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.\" Communications, Inc. trademarks, including the mark "WHISTLE
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.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as
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.\" such appears in the above copyright notice or in the software.
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.\"
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.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
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.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
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.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
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.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
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.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
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.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
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.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
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.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
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.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
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.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
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.\" OF SUCH DAMAGE.
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.\"
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.\" Author: Archie Cobbs <archie@FreeBSD.org>
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.\"
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.\" $FreeBSD$
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.\"
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.Dd May 5, 2010
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.Dt NG_BRIDGE 4
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.Os
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.Sh NAME
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.Nm ng_bridge
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.Nd Ethernet bridging netgraph node type
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.Sh SYNOPSIS
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.In sys/types.h
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.In netgraph/ng_bridge.h
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.Sh DESCRIPTION
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The
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.Nm bridge
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node type performs Ethernet bridging over one or more links.
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Each link (represented by a connected hook) is used to transmit
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and receive raw Ethernet frames.
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As packets are received, the node learns which link each
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host resides on.
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Packets unicast to a known host are directed out the appropriate
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link only, and other links are spared the traffic.
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This behavior is in contrast to a hub, which always forwards
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every received packet to every other link.
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.Sh LOOP DETECTION
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The
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.Nm bridge
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node incorporates a simple loop detection algorithm.
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A loop is when two ports are connected to the same physical medium.
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Loops are important to avoid because of packet storms, which severely
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degrade performance.
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A packet storm results when the same packet is sent and received
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over and over again.
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If a host is detected on link A, and is then detected on link B
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within a certain time period after first being detected on link A,
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then link B is considered to be a looped back link.
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The time period is called the minimum stable time.
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.Pp
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A looped back link will be temporarily muted, i.e., all traffic
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received on that link is ignored.
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.Sh IPFW PROCESSING
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Processing of IP packets via the
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.Xr ipfirewall 4
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mechanism on a per-link basis is not yet implemented.
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.Sh HOOKS
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This node type supports up to
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.Dv NG_BRIDGE_MAX_LINKS
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hooks.
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Each connected hook represents a bridged link.
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The hooks are named
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.Dv link0 ,
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.Dv link1 ,
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etc.
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Typically these hooks are connected to the
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.Dv lower
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hooks of one or more
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.Xr ng_ether 4
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nodes.
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To connect the host machine to a bridged network, simply connect the
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.Dv upper
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hook of an
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.Xr ng_ether 4
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node to the bridge node.
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.Sh CONTROL MESSAGES
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This node type supports the generic control messages, plus the
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following:
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.Bl -tag -width foo
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.It Dv NGM_BRIDGE_SET_CONFIG Pq Ic setconfig
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Set the node configuration.
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This command takes a
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.Dv "struct ng_bridge_config"
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as an argument:
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.Bd -literal -offset 0n
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/* Node configuration structure */
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struct ng_bridge_config {
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u_char ipfw[NG_BRIDGE_MAX_LINKS]; /* enable ipfw */
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u_char debugLevel; /* debug level */
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uint32_t loopTimeout; /* link loopback mute time */
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uint32_t maxStaleness; /* max host age before nuking */
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uint32_t minStableAge; /* min time for a stable host */
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};
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.Ed
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.Pp
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The
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.Dv ipfw
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array enables
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.Xr ipfirewall 4
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processing of IP packets received on the corresponding links.
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The
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.Dv debugLevel
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field sets the debug level on the node.
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At level of 2 or greater, detected loops are logged.
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The default level is 1.
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.Pp
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The
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.Dv loopTimeout
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determines how long (in seconds) a looped link is muted.
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The default is 60 seconds.
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The
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.Dv maxStaleness
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parameter determines how long a period of inactivity before
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a host's entry is forgotten.
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The default is 15 minutes.
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The
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.Dv minStableAge
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determines how quickly a host must jump from one link to another
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before we declare a loopback condition.
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The default is one second.
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.Pp
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.It Dv NGM_BRIDGE_GET_CONFIG Pq Ic getconfig
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Returns the current configuration as a
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.Dv "struct ng_bridge_config" .
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.It Dv NGM_BRIDGE_RESET Pq Ic reset
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Causes the node to forget all hosts and unmute all links.
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The node configuration is not changed.
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.It Dv NGM_BRIDGE_GET_STATS Pq Ic getstats
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This command takes a four byte link number as an argument and
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returns a
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.Dv "struct ng_bridge_link_stats"
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containing statistics for the corresponding link, which must be
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currently connected:
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.Bd -literal -offset 0n
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/* Statistics structure (one for each link) */
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struct ng_bridge_link_stats {
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uint64_t recvOctets; /* total octets rec'd on link */
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uint64_t recvPackets; /* total pkts rec'd on link */
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uint64_t recvMulticasts; /* multicast pkts rec'd on link */
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uint64_t recvBroadcasts; /* broadcast pkts rec'd on link */
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uint64_t recvUnknown; /* pkts rec'd with unknown dest addr */
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uint64_t recvRunts; /* pkts rec'd less than 14 bytes */
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uint64_t recvInvalid; /* pkts rec'd with bogus source addr */
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uint64_t xmitOctets; /* total octets xmit'd on link */
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uint64_t xmitPackets; /* total pkts xmit'd on link */
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uint64_t xmitMulticasts; /* multicast pkts xmit'd on link */
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uint64_t xmitBroadcasts; /* broadcast pkts xmit'd on link */
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uint64_t loopDrops; /* pkts dropped due to loopback */
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uint64_t loopDetects; /* number of loop detections */
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uint64_t memoryFailures; /* times couldn't get mem or mbuf */
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};
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.Ed
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.It Dv NGM_BRIDGE_CLR_STATS Pq Ic clrstats
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This command takes a four byte link number as an argument and
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clears the statistics for that link.
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.It Dv NGM_BRIDGE_GETCLR_STATS Pq Ic getclrstats
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Same as
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.Dv NGM_BRIDGE_GET_STATS ,
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but also atomically clears the statistics as well.
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.It Dv NGM_BRIDGE_GET_TABLE Pq Ic gettable
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Returns the current host mapping table used to direct packets, in a
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.Dv "struct ng_bridge_host_ary" .
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.It Dv NGM_BRIDGE_SET_PERSISTENT Pq Ic setpersistent
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This command sets the persistent flag on the node, and takes no arguments.
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.El
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.Sh SHUTDOWN
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This node shuts down upon receipt of a
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.Dv NGM_SHUTDOWN
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control message, or when all hooks have been disconnected. Setting the
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persistent flag via a
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.Dv NGM_BRIDGE_SET_PERSISTENT
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control message disables automatic node shutdown when the last hook gets
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disconnected.
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.Sh FILES
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.Bl -tag -width XXXXXXXX -compact
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.It Pa /usr/share/examples/netgraph/ether.bridge
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Example script showing how to set up a bridging network
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.El
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.Sh SEE ALSO
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.Xr if_bridge 4 ,
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.Xr netgraph 4 ,
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.Xr ng_ether 4 ,
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.Xr ng_hub 4 ,
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.Xr ng_one2many 4 ,
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.Xr ngctl 8
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.Sh HISTORY
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The
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.Nm
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node type was implemented in
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.Fx 4.2 .
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.Sh AUTHORS
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.An Archie Cobbs Aq archie@FreeBSD.org
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