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1 .\" Copyright (c) 2000 Whistle Communications, Inc.
2 .\" All rights reserved.
3 .\"
4 .\" Subject to the following obligations and disclaimer of warranty, use and
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6 .\" without modifications are expressly permitted by Whistle Communications;
7 .\" provided, however, that:
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9 .\" copyright notice above and the following disclaimer of warranties; and
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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
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29 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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32 .\"
33 .\" Author: Archie Cobbs <archie@FreeBSD.org>
34 .\"
35 .\" $FreeBSD$
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/ng_bridge.h
46 .Sh DESCRIPTION
47 The
48 .Nm bridge
49 node type performs Ethernet bridging over one or more links.
50 Each link (represented by a connected hook) is used to transmit
51 and receive raw Ethernet frames.
52 As packets are received, the node learns which link each
53 host resides on.
54 Packets unicast to a known host are directed out the appropriate
55 link only, and other links are spared the traffic.
56 This behavior is in contrast to a hub, which always forwards
57 every received packet to every other link.
58 .Sh LOOP DETECTION
59 The
60 .Nm bridge
61 node incorporates a simple loop detection algorithm.
62 A loop is when two ports are connected to the same physical medium.
63 Loops are important to avoid because of packet storms, which severely
64 degrade performance.
65 A packet storm results when the same packet is sent and received
66 over and over again.
67 If a host is detected on link A, and is then detected on link B
68 within a certain time period after first being detected on link A,
69 then link B is considered to be a looped back link.
70 The time period is called the minimum stable time.
71 .Pp
72 A looped back link will be temporarily muted, i.e., all traffic
73 received on that link is ignored.
74 .Sh IPFW PROCESSING
75 Processing of IP packets via the
76 .Xr ipfirewall 4
77 mechanism on a per-link basis is not yet implemented.
78 .Sh HOOKS
79 This node type supports up to
80 .Dv NG_BRIDGE_MAX_LINKS
81 hooks.
82 Each connected hook represents a bridged link.
83 The hooks are named
84 .Dv link0 ,
85 .Dv link1 ,
86 etc.
87 Typically these hooks are connected to the
88 .Dv lower
89 hooks of one or more
90 .Xr ng_ether 4
91 nodes.
92 To connect the host machine to a bridged network, simply connect the
93 .Dv upper
94 hook of an
95 .Xr ng_ether 4
96 node to the bridge node.
97 .Sh CONTROL MESSAGES
98 This node type supports the generic control messages, plus the
99 following:
100 .Bl -tag -width foo
101 .It Dv NGM_BRIDGE_SET_CONFIG
102 Set the node configuration.
103 This command takes a
104 .Dv "struct ng_bridge_config"
105 as an argument:
106 .Bd -literal -offset 0n
107 /* Node configuration structure */
108 struct 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
117 The
118 .Dv ipfw
119 array enables
120 .Xr ipfirewall 4
121 processing of IP packets received on the corresponding links.
122 The
123 .Dv debugLevel
124 field sets the debug level on the node.
125 At level of 2 or greater, detected loops are logged.
126 The default level is 1.
127 .Pp
128 The
129 .Dv loopTimeout
130 determines how long (in seconds) a looped link is muted.
131 The default is 60 seconds.
132 The
133 .Dv maxStaleness
134 parameter determines how long a period of inactivity before
135 a host's entry is forgotten.
136 The default is 15 minutes.
137 The
138 .Dv minStableAge
139 determines how quickly a host must jump from one link to another
140 before we declare a loopback condition.
141 The default is one second.
142 .Pp
143 .It Dv NGM_BRIDGE_GET_CONFIG
144 Returns the current configuration as a
145 .Dv "struct ng_bridge_config" .
146 .It Dv NGM_BRIDGE_RESET
147 Causes the node to forget all hosts and unmute all links.
148 The node configuration is not changed.
149 .It Dv NGM_BRIDGE_GET_STATS
150 This command takes a four byte link number as an argument and
151 returns a
152 .Dv "struct ng_bridge_link_stats"
153 containing statistics for the corresponding link, which must be
154 currently connected:
155 .Bd -literal -offset 0n
156 /* Statistics structure (one for each link) */
157 struct ng_bridge_link_stats {
158 u_int64_t recvOctets; /* total octets rec'd on link */
159 u_int64_t recvPackets; /* total pkts rec'd on link */
160 u_int64_t recvMulticasts; /* multicast pkts rec'd on link */
161 u_int64_t recvBroadcasts; /* broadcast pkts rec'd on link */
162 u_int64_t recvUnknown; /* pkts rec'd with unknown dest addr */
163 u_int64_t recvRunts; /* pkts rec'd less than 14 bytes */
164 u_int64_t recvInvalid; /* pkts rec'd with bogus source addr */
165 u_int64_t xmitOctets; /* total octets xmit'd on link */
166 u_int64_t xmitPackets; /* total pkts xmit'd on link */
167 u_int64_t xmitMulticasts; /* multicast pkts xmit'd on link */
168 u_int64_t xmitBroadcasts; /* broadcast pkts xmit'd on link */
169 u_int64_t loopDrops; /* pkts dropped due to loopback */
170 u_int64_t loopDetects; /* number of loop detections */
171 u_int64_t memoryFailures; /* times couldn't get mem or mbuf */
172 };
173 .Ed
174 .It Dv NGM_BRIDGE_CLR_STATS
175 This command takes a four byte link number as an argument and
176 clears the statistics for that link.
177 .It Dv NGM_BRIDGE_GETCLR_STATS
178 Same as
179 .Dv NGM_BRIDGE_GET_STATS ,
180 but also atomically clears the statistics as well.
181 .It Dv NGM_BRIDGE_GET_TABLE
182 Returns the current host mapping table used to direct packets, in a
183 .Dv "struct ng_bridge_host_ary" .
184 .El
185 .Sh SHUTDOWN
186 This node shuts down upon receipt of a
187 .Dv NGM_SHUTDOWN
188 control message, or when all hooks have been disconnected.
189 .Sh FILES
190 .Bl -tag -width XXXXXXXX -compact
191 .It Pa /usr/share/examples/netgraph/ether.bridge
192 Example script showing how to set up a bridging network
193 .El
194 .Sh SEE ALSO
195 .Xr if_bridge 4 ,
196 .Xr netgraph 4 ,
197 .Xr ng_ether 4 ,
198 .Xr ng_hub 4 ,
199 .Xr ng_one2many 4 ,
200 .Xr ngctl 8
201 .Sh HISTORY
202 The
203 .Nm
204 node type was implemented in
205 .Fx 4.2 .
206 .Sh AUTHORS
207 .An Archie Cobbs Aq archie@FreeBSD.org