routed(1M) routed(1M)
NAME
routed, in.routed - network routing daemon
SYNOPSIS
in.routed [-sqltv] [logfile]
in.routed [-D logdir]
DESCRIPTION
routed is invoked at boot time to manage the network routing tables.
The routing daemon uses a variant of the Xerox NS Routing Information
Protocol in keeping the kernel routing table entries up-to-date.
In normal operation routed listens on udp(7) socket 520 (decimal) for
routing information packets. If the host is an internetwork router, it
periodically supplies copies of its routing tables to any directly
connected hosts and networks.
routed uses the SIOCGIFCONF ioctl(2) to find those directly connected
interfaces configured into the system and marked "up" (the software
loopback interface is ignored). If multiple interfaces are present, it
is assumed the host will forward packets between networks. routed then
transmits a request packet on each interface (using a broadcast packet
if the interface supports it) and enters a loop, listening for request
and response packets from other hosts.
When a request packet is received, routed formulates a reply based on
the information maintained in its internal tables. The response packet
generated contains a list of known routes, each marked with a "hop
count" metric (a count of 16, or greater, is considered "infinite").
The metric associated with each route returned provides a metric rela-
tive to the sender.
request packets received by routed are used to update the routing
tables if one of the following conditions is satisfied:
1) No routing table entry exists for the destination network or host,
and the metric indicates the destination is "reachable" (that is,
the hop count is not infinite).
2) The source host of the packet is the same as the router in the
existing routing table entry. That is, updated information is being
received from the very internetwork router through which packets
for the destination are being routed.
3) The existing entry in the routing table has not been updated for
some time (defined to be 90 seconds) and the route is at least as
cost effective as the current route.
4) The new route describes a shorter route to the destination than the
one currently stored in the routing tables; the metric of the new
route is compared against the one stored in the table to decide this.
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When an update is applied, routed records the change in its internal
tables and generates a response packet to all directly connected hosts
and networks. routed waits a short period of time (no more than 30
seconds) before modifying the kernel's routing tables to allow possi-
ble unstable situations to settle.
In addition to processing incoming packets, routed also periodically
checks the routing table entries. If an entry has not been updated for
3 minutes, the entry's metric is set to infinity and marked for dele-
tion. Deletions are delayed an additional 60 seconds to insure the
invalidation is propagated throughout the internet.
Hosts acting as internetwork routers gratuitously supply their routing
tables every 30 seconds to all directly connected hosts and networks.
OPTIONS
-s Supplying the -s option forces routed to supply routing informa-
tion whether it is acting as an internetwork router or not.
-q The -q option is the opposite of the -s option.
-l The -l ("logswitch") option allows logging to be switched on and
off and allows the logfile name to be modified by RIP TRACEON and
TRACEOFF packets received by routed.
If -l is not specified then TRACEON and TRACEOFF requests will be
ignored.
-t If the -t option is specified, all packets sent or received are
printed on the standard output (or into the logfile if one is
specified). In addition, routed will not divorce itself from the
controlling terminal so that interrupts from the keyboard will
kill the process.
-v The -v option causes timestamped records of internal routed
activity (generally modifications to its routing table) to be
written to logfile.
-D logdir
The -D option provides the name of the directory in which the
logfile is located. logdir must be given as an absolute path. The
default logdir is /var/adm/log/in.routed.
logfile
The logfile argument, if present, is interpreted as the name of a
file in the logdir directory in which information concerning
routed's operation should be logged.
Records are appended to the logfile. If specified on the command
line the logfile will be created by routed. In the absence of -t
or -v only exceptional events are logged.
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If the -l option is given then the logfile name may be changed
and logging may be switched on and off by RIP TRACEON and
TRACEOFF packets sent to routed.
A logfile named in a TRACEON request must already exist in the
logdir directory. In this case routed will not create the
logfile. Activities triggered by TRACEON and TRACEOFF packets are
reported through the syslog(3C) facility.
In addition to the facilities described above, routed supports the
notion of "distant" passive and active gateways. When routed is
started up, it reads the file gateways to find gateways which may not
be identified using the SIOGIFCONF ioctl. Gateways specified in this
manner should be marked passive if they are not expected to exchange
routing information, while gateways marked active should be willing to
exchange routing information (that is, they should have a routed pro-
cess running on # the machine). Passive gateways are maintained in the
routing tables forever and information regarding their existence is
included in any routing information transmitted. Active gateways are
treated equally to network interfaces. Routing information is distri-
buted to the gateway and if no routing information is received for a
period of the time, the associated route is deleted.
The gateways is comprised of a series of lines, each in the following
format:
<net | host> filename1 gateway filename2 metric value <passive|active>
The net or host keyword indicates if the route is to a network or
specific host.
filename1 is the name of the destination network or host. This may be
a symbolic name located in networks(4) or hosts(4), or an Internet
address specified in "dot" notation; see inet(3N).
filename2 is the name or address of the gateway to which messages
should be forwarded.
value is a metric indicating the hop count to the destination host or
network.
The keyword passive or active indicates if the gateway should be
treated as passive or active (as described above).
NOTES
The kernel's routing tables may not correspond to those of routed for
short periods of time while processes utilizing existing routes exit;
the only remedy for this is to place the routing process in the ker-
nel.
routed should listen to intelligent interfaces, such as an IMP, and to
error protocols, such as ICMP, to gather more information.
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FILES
/etc/gateways for distant gateways
/etc/networks
/etc/hosts
SEE ALSO
ioctl(2), hosts(4), networks(4), inet(7), udp(7).
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