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2c4d288d C |
1 | .TH ROUTED 8C "3 February 1983" |
2 | .UC 4 | |
3 | .SH NAME | |
4 | routed \- network routing daemon | |
5 | .SH SYNOPSIS | |
6 | .B /etc/routed | |
7 | [ | |
8 | .B \-s | |
9 | ] [ | |
10 | .B \-q | |
11 | ] [ | |
12 | .B \-t | |
13 | ] [ | |
14 | .I logfile | |
15 | ] | |
16 | .SH DESCRIPTION | |
17 | .I Routed | |
18 | is invoked at boot time to manage the network routing tables. | |
19 | The routing daemon uses a variant of the Xerox NS Routing | |
20 | Information Protocol in maintaining up to date kernel routing | |
21 | table entries. | |
22 | .PP | |
23 | In normal operation | |
24 | .I routed | |
25 | listens on | |
26 | .IR udp (4P) | |
27 | socket 520 (decimal) | |
28 | for routing information packets. If the host is an | |
29 | internetwork router, it periodically supplies copies | |
30 | of its routing tables to any directly connected hosts | |
31 | and networks. | |
32 | .PP | |
33 | When | |
34 | .I routed | |
35 | is started, it uses the SIOCGIFCONF | |
36 | .I ioctl | |
37 | to find those | |
38 | directly connected interfaces configured into the | |
39 | system and marked ``up'' (the software loopback interface | |
40 | is ignored). If multiple interfaces | |
41 | are present, it is assumed the host will forward packets | |
42 | between networks. | |
43 | .I Routed | |
44 | then transmits a | |
45 | .I request | |
46 | packet on each interface (using a broadcast packet if | |
47 | the interface supports it) and enters a loop, listening | |
48 | for | |
49 | .I request | |
50 | and | |
51 | .I response | |
52 | packets from other hosts. | |
53 | .PP | |
54 | When a | |
55 | .I request | |
56 | packet is received, | |
57 | .I routed | |
58 | formulates a reply based on the information maintained in its | |
59 | internal tables. The | |
60 | .I response | |
61 | packet generated contains a list of known routes, each marked | |
62 | with a ``hop count'' metric (a count of 16, or greater, is | |
63 | considered ``infinite''). The metric associated with each | |
64 | route returned provides a metric | |
65 | .IR "relative to the sender" . | |
66 | .PP | |
67 | .I Response | |
68 | packets received by | |
69 | .I routed | |
70 | are used to update the routing tables if one of the following | |
71 | conditions is satisfied: | |
72 | .TP | |
73 | (1) | |
74 | No routing table entry exists for the destination network | |
75 | or host, and the metric indicates the destination is ``reachable'' | |
76 | (i.e. the hop count is not infinite). | |
77 | .TP | |
78 | (2) | |
79 | The source host of the packet is the same as the router in the | |
80 | existing routing table entry. That is, updated information is | |
81 | being received from the very internetwork router through which | |
82 | packets for the destination are being routed. | |
83 | .TP | |
84 | (3) | |
85 | The existing entry in the routing table has not been updated for | |
86 | some time (defined to be 90 seconds) and the route is at least | |
87 | as cost effective as the current route. | |
88 | .TP | |
89 | (4) | |
90 | The new route describes a shorter route to the destination than | |
91 | the one currently stored in the routing tables; the metric of | |
92 | the new route is compared against the one stored in the table | |
93 | to decide this. | |
94 | .PP | |
95 | When an update is applied, | |
96 | .I routed | |
97 | records the change in its internal tables and generates a | |
98 | .I response | |
99 | packet to all directly connected hosts and networks. | |
100 | .I Routed | |
101 | waits a short period | |
102 | of time (no more than 30 seconds) before modifying the kernel's | |
103 | routing tables to allow possible unstable situations to settle. | |
104 | .PP | |
105 | In addition to processing incoming packets, | |
106 | .I routed | |
107 | also periodically checks the routing table entries. | |
108 | If an entry has not been updated for 3 minutes, the entry's metric | |
109 | is set to infinity and marked for deletion. Deletions are delayed | |
110 | an additional 60 seconds to insure the invalidation is propagated | |
111 | throughout the internet. | |
112 | .PP | |
113 | Hosts acting as internetwork routers gratuitously supply their | |
114 | routing tables every 30 seconds to all directly connected hosts | |
115 | and networks. | |
116 | .PP | |
117 | Supplying the | |
118 | .B \-s | |
119 | option forces | |
120 | .I routed | |
121 | to supply routing information whether it is acting as an internetwork | |
122 | router or not. | |
123 | The | |
124 | .B \-q | |
125 | option is the opposite of the | |
126 | .B \-s | |
127 | option. If the | |
128 | .B \-t | |
129 | option is specified, all packets sent or received are | |
130 | printed on the standard output. In addition, | |
131 | .I routed | |
132 | will not divorce itself from the controlling terminal | |
133 | so that interrupts from the keyboard will kill the process. | |
134 | Any other argument supplied is interpreted as the name | |
135 | of file in which | |
136 | .IR routed 's | |
137 | actions should be logged. This log contains information | |
138 | about any changes to the routing tables and a history of | |
139 | recent messages sent and received which are related to | |
140 | the changed route. | |
141 | .PP | |
142 | In addition to the facilities described above, | |
143 | .I routed | |
144 | supports the notion of ``distant'' | |
145 | .I passive | |
146 | and | |
147 | .I active | |
148 | gateways. When | |
149 | .I routed | |
150 | is started up, it reads the file | |
151 | .I /etc/gateways | |
152 | to find gateways which may not be identified using | |
153 | the SIOGIFCONF | |
154 | .IR ioctl . | |
155 | Gateways specified in this manner should be marked passive | |
156 | if they are not expected to exchange routing information, | |
157 | while gateways marked active | |
158 | should be willing to exchange routing information (i.e. | |
159 | they should have a | |
160 | .I routed | |
161 | process running on the machine). | |
162 | Passive gateways are maintained in the | |
163 | routing tables forever and information | |
164 | regarding their existence is included in | |
165 | any routing information transmitted. | |
166 | Active gateways are treated equally to network | |
167 | interfaces. Routing information is distributed | |
168 | to the gateway and if no routing information is | |
169 | received for a period of the time, the associated | |
170 | route is deleted. | |
171 | .PP | |
172 | The | |
173 | .I /etc/gateways | |
174 | is comprised of a series of lines, each in | |
175 | the following format: | |
176 | .PP | |
177 | .nf | |
178 | < \fBnet\fP | \fBhost\fP > \fIname1\fP \fBgateway\fP \fIname2\fP \fBmetric\fP \fIvalue\fP < \fBpassive\fP | \fBactive\fP > | |
179 | .fi | |
180 | .PP | |
181 | The | |
182 | .B net | |
183 | or | |
184 | .B host | |
185 | keyword indicates if the route is to a network or specific host. | |
186 | .PP | |
187 | .I Name1 | |
188 | is the name of the destination network or host. This may be a | |
189 | symbolic name located in | |
190 | .I /etc/networks | |
191 | or | |
192 | .IR /etc/hosts , | |
193 | or an Internet address specified in ``dot'' notation; see | |
194 | .IR inet (3N). | |
195 | .PP | |
196 | .I Name2 | |
197 | is the name or address of the gateway to which messages should | |
198 | be forwarded. | |
199 | .PP | |
200 | .I Value | |
201 | is a metric indicating the hop count to the destination host | |
202 | or network. | |
203 | .PP | |
204 | The keyword | |
205 | .B passive | |
206 | or | |
207 | .B active | |
208 | indicates if the gateway should be treated as | |
209 | .I passive | |
210 | or | |
211 | .I active | |
212 | (as described above). | |
213 | .SH FILES | |
214 | .DT | |
215 | /etc/gateways for distant gateways | |
216 | .SH "SEE ALSO" | |
217 | ``Internet Transport Protocols'', XSIS 028112, Xerox System Integration | |
218 | Standard. | |
219 | .br | |
220 | udp(4P) | |
221 | .SH BUGS | |
222 | The kernel's routing tables may not correspond to those of | |
223 | .I routed | |
224 | for short periods of time while processes utilizing existing | |
225 | routes exit; the only remedy for this is to place the routing | |
226 | process in the kernel. | |
227 | .PP | |
228 | .I Routed | |
229 | should listen to intelligent interfaces, such as an IMP, and | |
230 | to error protocols, such as ICMP, to gather more information. |