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.\" 37.Dd August 31, 2000 38.Dt NG_BRIDGE 4 39.Os 40.Sh NAME 41.Nm ng_bridge 42.Nd Ethernet bridging netgraph node type 43.Sh SYNOPSIS 44.In sys/types.h 45.In netgraph/bridge/ng_bridge.h 46.Sh DESCRIPTION 47The 48.Nm bridge 49node type performs Ethernet bridging over one or more links. 50Each link (represented by a connected hook) is used to transmit 51and receive raw Ethernet frames. 52As packets are received, the node learns which link each 53host resides on. 54Packets unicast to a known host are directed out the appropriate 55link only, and other links are spared the traffic. 56This behavior is in contrast to a hub, which always forwards 57every received packet to every other link. 58.Sh LOOP DETECTION 59The 60.Nm bridge 61node incorporates a simple loop detection algorithm. 62A loop is when two ports are connected to the same physical medium. 63Loops are important to avoid because of packet storms, which severely 64degrade performance. 65A packet storm results when the same packet is sent and received 66over and over again. 67If a host is detected on link A, and is then detected on link B 68within a certain time period after first being detected on link A, 69then link B is considered to be a looped back link. 70The time period is called the minimum stable time. 71.Pp 72A looped back link will be temporarily muted, i.e., all traffic 73received on that link is ignored. 74.Sh IPFW PROCESSING 75Processing of IP packets via the 76.Xr ipfirewall 4 77mechanism on a per-link basis is not yet implemented. 78.Sh HOOKS 79This node type supports up to 80.Dv NG_BRIDGE_MAX_LINKS 81hooks. 82Each connected hook represents a bridged link. 83The hooks are named 84.Dv link0 , 85.Dv link1 , 86etc. 87Typically these hooks are connected to the 88.Dv lower 89hooks of one or more 90.Xr ng_ether 4 91nodes. 92To connect the host machine to a bridged network, simply connect the 93.Dv upper 94hook of an 95.Xr ng_ether 4 96node to the bridge node. 97.Sh CONTROL MESSAGES 98This node type supports the generic control messages, plus the 99following: 100.Bl -tag -width foo 101.It Dv NGM_BRIDGE_SET_CONFIG 102Set the node configuration. 103This command takes a 104.Dv "struct ng_bridge_config" 105as an argument: 106.Bd -literal -offset 0n 107/* Node configuration structure */ 108struct ng_bridge_config { 109 u_char ipfw[NG_BRIDGE_MAX_LINKS]; /* enable ipfw */ 110 u_char debugLevel; /* debug level */ 111 u_int32_t loopTimeout; /* link loopback mute time */ 112 u_int32_t maxStaleness; /* max host age before nuking */ 113 u_int32_t minStableAge; /* min time for a stable host */ 114}; 115.Ed 116.Pp 117The 118.Dv ipfw 119array enables 120.Xr ipfirewall 4 121processing of IP packets received on the corresponding links. 122The 123.Dv debugLevel 124field sets the debug level on the node. 125At level of 2 or greater, detected loops are logged. 126The default level is 1. 127.Pp 128The 129.Dv loopTimeout 130determines how long (in seconds) a looped link is muted. 131The default is 60 seconds. 132The 133.Dv maxStaleness 134parameter determines how long a period of inactivity before 135a host's entry is forgotten. 136The default is 15 minutes. 137The 138.Dv minStableAge 139determines how quickly a host must jump from one link to another 140before we declare a loopback condition. 141The default is one second. 142.It Dv NGM_BRIDGE_GET_CONFIG 143Returns the current configuration as a 144.Dv "struct ng_bridge_config" . 145.It Dv NGM_BRIDGE_RESET 146Causes the node to forget all hosts and unmute all links. 147The node configuration is not changed. 148.It Dv NGM_BRIDGE_GET_STATS 149This command takes a four byte link number as an argument and 150returns a 151.Dv "struct ng_bridge_link_stats" 152containing statistics for the corresponding link, which must be 153currently connected: 154.Bd -literal -offset 0n 155/* Statistics structure (one for each link) */ 156struct ng_bridge_link_stats { 157 u_int64_t recvOctets; /* total octets rec'd on link */ 158 u_int64_t recvPackets; /* total pkts rec'd on link */ 159 u_int64_t recvMulticasts; /* multicast pkts rec'd on link */ 160 u_int64_t recvBroadcasts; /* broadcast pkts rec'd on link */ 161 u_int64_t recvUnknown; /* pkts rec'd with unknown dest addr */ 162 u_int64_t recvRunts; /* pkts rec'd less than 14 bytes */ 163 u_int64_t recvInvalid; /* pkts rec'd with bogus source addr */ 164 u_int64_t xmitOctets; /* total octets xmit'd on link */ 165 u_int64_t xmitPackets; /* total pkts xmit'd on link */ 166 u_int64_t xmitMulticasts; /* multicast pkts xmit'd on link */ 167 u_int64_t xmitBroadcasts; /* broadcast pkts xmit'd on link */ 168 u_int64_t loopDrops; /* pkts dropped due to loopback */ 169 u_int64_t loopDetects; /* number of loop detections */ 170 u_int64_t memoryFailures; /* times couldn't get mem or mbuf */ 171}; 172.Ed 173.It Dv NGM_BRIDGE_CLR_STATS 174This command takes a four byte link number as an argument and 175clears the statistics for that link. 176.It Dv NGM_BRIDGE_GETCLR_STATS 177Same as 178.Dv NGM_BRIDGE_GET_STATS , 179but also atomically clears the statistics as well. 180.It Dv NGM_BRIDGE_GET_TABLE 181Returns the current host mapping table used to direct packets, in a 182.Dv "struct ng_bridge_host_ary" . 183.El 184.Sh SHUTDOWN 185This node shuts down upon receipt of a 186.Dv NGM_SHUTDOWN 187control message, or when all hooks have been disconnected. 188.Sh FILES 189.Bl -tag -width XXXXXXXX -compact 190.It Pa /usr/share/examples/netgraph/ether.bridge 191Example script showing how to set up a bridging network 192.El 193.Sh SEE ALSO 194.Xr bridge 4 , 195.Xr netgraph 4 , 196.Xr ng_ether 4 , 197.Xr ngctl 8 198.Sh HISTORY 199The 200.Nm 201node type was implemented in 202.Fx 4.2 . 203.Sh AUTHORS 204.An Archie Cobbs Aq Mt archie@FreeBSD.org 205