ROUTED(8N) COMMAND REFERENCE ROUTED(8N)
NAME
routed - network routing daemon
SYNOPSIS
/etc/routed [ -s ] [ -q ] [ -t ] [ logfile ]
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 maintaining up to date
kernel routing table entries.
In normal operation routed listens on udp(4n) 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.
When routed is started, it uses the SIOCGIFCONF ioctl 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
relative to the sender.
Response 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'' (i.e. 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
Printed 10/17/86 1
ROUTED(8N) COMMAND REFERENCE ROUTED(8N)
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.
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 possible 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 deletion. 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.
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
/etc/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 (i.e.
they should have a routed process 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 distributed to the gateway and if no routing
information is received for a period of the time, the
associated route is deleted.
The /etc/gateways is comprised of a series of lines, each in
the following format:
< net | host > name1 gateway name2 metric value < passive | active >
The net or host keyword indicates if the route is to a
network or specific host.
Printed 10/17/86 2
ROUTED(8N) COMMAND REFERENCE ROUTED(8N)
Name1 is the name of the destination network or host. This
may be a symbolic name located in /etc/networks or
/etc/hosts, or an Internet address specified in ``dot''
notation; see inet(3n).
Name2 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).
OPTIONS
-s This option forces routed to supply routing information
whether it is acting as an internetwork router or not.
-q This option is the opposite of the -s option.
-t This option causes, all packets sent or received to be
printed on the standard output. In addition, routed
will not divorce itself from the controlling terminal so
that interrupts from the keyboard will kill the process.
logfile
Any other argument supplied is interpreted as the name
of the file in which routed's actions should be logged.
This log contains information about any changes to the
routing tables and a history of recent messages sent and
received which are related to the changed route.
FILES
/etc/gateways for distant gateways
RETURN VALUE
[0] Routed is running.
[1] Routed is not running.
[-1] No action taken.
CAVEATS
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 kernel.
SEE ALSO
udp(4n).
Printed 10/17/86 3
%%index%%
na:72,67;
sy:139,224;
de:363,2741;3248,3087;6479,707;
op:7186,996;
fi:8182,105;
rv:8287,279;
ca:8566,319;
se:8885,77;
%%index%%000000000151