1.\" Copyright (c) 2000 Whistle Communications, Inc. 2.\" All rights reserved. 3.\" 4.\" Subject to the following obligations and disclaimer of warranty, use and 5.\" redistribution of this software, in source or object code forms, with or 6.\" without modifications are expressly permitted by Whistle Communications; 7.\" provided, however, that: 8.\" 1. Any and all reproductions of the source or object code must include the 9.\" copyright notice above and the following disclaimer of warranties; and 10.\" 2. No rights are granted, in any manner or form, to use Whistle 11.\" Communications, Inc. trademarks, including the mark "WHISTLE 12.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as 13.\" such appears in the above copyright notice or in the software. 14.\" 15.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 16.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 17.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 18.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 19.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 20.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 21.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 22.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 23.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 24.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 25.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 26.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 27.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 31.\" OF SUCH DAMAGE. 32.\" 33.\" Author: Archie Cobbs <archie@FreeBSD.org> 34.\" 35.\" $FreeBSD: src/share/man/man4/ng_bridge.4,v 1.1.2.6 2001/12/17 11:30:12 ru Exp $ 36.\" $DragonFly: src/share/man/man4/ng_bridge.4,v 1.4 2006/05/26 19:39:39 swildner Exp $ 37.\" 38.Dd August 31, 2000 39.Dt NG_BRIDGE 4 40.Os 41.Sh NAME 42.Nm ng_bridge 43.Nd Ethernet bridging netgraph node type 44.Sh SYNOPSIS 45.In sys/types.h 46.In netgraph/bridge/ng_bridge.h 47.Sh DESCRIPTION 48The 49.Nm bridge 50node type performs Ethernet bridging over one or more links. 51Each link (represented by a connected hook) is used to transmit 52and receive raw Ethernet frames. 53As packets are received, the node learns which link each 54host resides on. 55Packets unicast to a known host are directed out the appropriate 56link only, and other links are spared the traffic. 57This behavior is in contrast to a hub, which always forwards 58every received packet to every other link. 59.Sh LOOP DETECTION 60The 61.Nm bridge 62node incorporates a simple loop detection algorithm. 63A loop is when two ports are connected to the same physical medium. 64Loops are important to avoid because of packet storms, which severely 65degrade performance. 66A packet storm results when the same packet is sent and received 67over and over again. 68If a host is detected on link A, and is then detected on link B 69within a certain time period after first being detected on link A, 70then link B is considered to be a looped back link. 71The time period is called the minimum stable time. 72.Pp 73A looped back link will be temporarily muted, i.e., all traffic 74received on that link is ignored. 75.Sh IPFW PROCESSING 76Processing of IP packets via the 77.Xr ipfirewall 4 78mechanism on a per-link basis is not yet implemented. 79.Sh HOOKS 80This node type supports up to 81.Dv NG_BRIDGE_MAX_LINKS 82hooks. 83Each connected hook represents a bridged link. 84The hooks are named 85.Dv link0 , 86.Dv link1 , 87etc. 88Typically these hooks are connected to the 89.Dv lower 90hooks of one or more 91.Xr ng_ether 4 92nodes. 93To connect the host machine to a bridged network, simply connect the 94.Dv upper 95hook of an 96.Xr ng_ether 4 97node to the bridge node. 98.Sh CONTROL MESSAGES 99This node type supports the generic control messages, plus the 100following: 101.Bl -tag -width foo 102.It Dv NGM_BRIDGE_SET_CONFIG 103Set the node configuration. 104This command takes a 105.Dv "struct ng_bridge_config" 106as an argument: 107.Bd -literal -offset 0n 108/* Node configuration structure */ 109struct ng_bridge_config { 110 u_char ipfw[NG_BRIDGE_MAX_LINKS]; /* enable ipfw */ 111 u_char debugLevel; /* debug level */ 112 u_int32_t loopTimeout; /* link loopback mute time */ 113 u_int32_t maxStaleness; /* max host age before nuking */ 114 u_int32_t minStableAge; /* min time for a stable host */ 115}; 116.Ed 117.Pp 118The 119.Dv ipfw 120array enables 121.Xr ipfirewall 4 122processing of IP packets received on the corresponding links. 123The 124.Dv debugLevel 125field sets the debug level on the node. 126At level of 2 or greater, detected loops are logged. 127The default level is 1. 128.Pp 129The 130.Dv loopTimeout 131determines how long (in seconds) a looped link is muted. 132The default is 60 seconds. 133The 134.Dv maxStaleness 135parameter determines how long a period of inactivity before 136a host's entry is forgotten. 137The default is 15 minutes. 138The 139.Dv minStableAge 140determines how quickly a host must jump from one link to another 141before we declare a loopback condition. 142The default is one second. 143.Pp 144.It Dv NGM_BRIDGE_GET_CONFIG 145Returns the current configuration as a 146.Dv "struct ng_bridge_config" . 147.It Dv NGM_BRIDGE_RESET 148Causes the node to forget all hosts and unmute all links. 149The node configuration is not changed. 150.It Dv NGM_BRIDGE_GET_STATS 151This command takes a four byte link number as an argument and 152returns a 153.Dv "struct ng_bridge_link_stats" 154containing statistics for the corresponding link, which must be 155currently connected: 156.Bd -literal -offset 0n 157/* Statistics structure (one for each link) */ 158struct ng_bridge_link_stats { 159 u_int64_t recvOctets; /* total octets rec'd on link */ 160 u_int64_t recvPackets; /* total pkts rec'd on link */ 161 u_int64_t recvMulticasts; /* multicast pkts rec'd on link */ 162 u_int64_t recvBroadcasts; /* broadcast pkts rec'd on link */ 163 u_int64_t recvUnknown; /* pkts rec'd with unknown dest addr */ 164 u_int64_t recvRunts; /* pkts rec'd less than 14 bytes */ 165 u_int64_t recvInvalid; /* pkts rec'd with bogus source addr */ 166 u_int64_t xmitOctets; /* total octets xmit'd on link */ 167 u_int64_t xmitPackets; /* total pkts xmit'd on link */ 168 u_int64_t xmitMulticasts; /* multicast pkts xmit'd on link */ 169 u_int64_t xmitBroadcasts; /* broadcast pkts xmit'd on link */ 170 u_int64_t loopDrops; /* pkts dropped due to loopback */ 171 u_int64_t loopDetects; /* number of loop detections */ 172 u_int64_t memoryFailures; /* times couldn't get mem or mbuf */ 173}; 174.Ed 175.It Dv NGM_BRIDGE_CLR_STATS 176This command takes a four byte link number as an argument and 177clears the statistics for that link. 178.It Dv NGM_BRIDGE_GETCLR_STATS 179Same as 180.Dv NGM_BRIDGE_GET_STATS , 181but also atomically clears the statistics as well. 182.It Dv NGM_BRIDGE_GET_TABLE 183Returns the current host mapping table used to direct packets, in a 184.Dv "struct ng_bridge_host_ary" . 185.El 186.Sh SHUTDOWN 187This node shuts down upon receipt of a 188.Dv NGM_SHUTDOWN 189control message, or when all hooks have been disconnected. 190.Sh FILES 191.Bl -tag -width XXXXXXXX -compact 192.It Pa /usr/share/examples/netgraph/ether.bridge 193Example script showing how to set up a bridging network 194.El 195.Sh SEE ALSO 196.Xr bridge 4 , 197.Xr netgraph 4 , 198.Xr ng_ether 4 , 199.Xr ngctl 8 200.Sh HISTORY 201The 202.Nm 203node type was implemented in 204.Fx 4.2 . 205.Sh AUTHORS 206.An Archie Cobbs Aq archie@FreeBSD.org 207