ROUTE(8c,C) AIX TCP/IP User's Guide ROUTE(8c,C)
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route
PURPOSE
Manually manipulates the routing tables.
SYNTAX
+--------+ +-- add ---+ +----------+
route ---| +----+ |---| |---| one of |-- destination -...
+-| -f |-+ +- delete -+ | +------+ |
^| -n || +-| net |-+
|+----+| | host |
+------+ +------+
...- gateway -- metric ---|
DESCRIPTION
The route command is used to manually manipulate the network routing tables.
It normally is not needed, as the system routing table management daemon,
routed, tends to this task.
The route command accepts two commands: add, to add a route, and delete, to
delete a route. In addition the route command accepts the following
parameters:
destination
Is the destination host or network.
gateway
Is the next-hop gateway to which packets should be addressed.
metric
Is a count indicating the number of hops to the destination.
The metric is required for add commands. It must be zero if the destination is
on a directly-attached network, and nonzero if the route utilizes one or more
gateways. If adding a route with metric 0, the gateway given is the address of
this host on the common network, indicating the interface to be used for
transmission. Routes to a particular host are distinguished from those to a
network by interpreting the Internet address associated with destination.
The optional keywords net and host force the destination to be interpreted as a
network or a host, respectively. Otherwise, if the destination has a local
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address part of INADDR_ANY, or if the destination is the symbolic name of a
network, then the route is assumed to be to a network. It is presumed to be a
route to a host. If the route is to a destination connected via a gateway, the
metric should be greater than 0. All symbolic names specified for a
destination or gateway are looked up first as a host name using gethostbyname.
If this lookup fails, getnetbyname is then used to interpret the name as that
of a network.
The optional keyword default may be substituted for the destination parameter.
This causes the gateway specified as the next parameter to be treated as the
default exit point for the network. This "default gateway" will be used for
any packet with an unrecognized address. This provides a place for packets to
be sent when the host handling the packet can not find the Internet address in
its own route table. A "default" gateway" is very useful; it is often
specified when there are hosts in the network that are not running routed.
The route command uses a raw socket and the SIOCADDRT and SIOCDELRT ioctl's to
do its work. As such, only the superuser may modify the routing tables.
FLAGS
The route command options are:
-f Flushes the routing tables of all gateway entries. If this is used in
conjunction with one of the commands described above, the tables are
flushed prior to the command's application.
-n Prevents attempts to print host and network names symbolically when
reporting actions.
EXAMPLES
# /etc/route add newnet thishost 3
# /etc/route delete newnet thishost
MESSAGES
add [ host | network ] destination gateway
Explanation: The specified route is being added to the tables. The values
printed are from the routing table entry supplied in the ioctl call. If the
gateway address used was not the primary address of the gateway (the first one
returned by gethostbyname), the gateway address is printed numerically as well
as symbolically.
delete [ host | network ] destination gateway
Explanation: As above, but when deleting an entry.
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Flushing routing tables: destination gateway
Explanation: When the -f flag is specified, each routing table entry deleted
is indicated with a message of this form.
network is unreachable
Explanation: An attempt to add a route failed because the gateway listed was
not on a directly-connected network. The next-hop gateway must be given.
not in table
Explanation: A delete operation was attempted for an entry which wasn't
present in the tables.
routing table overflow
Explanation: An add operation was attempted, but the system was low on
resources and was unable to allocate memory to create the new entry.
RELATED INFORMATION
In this book: "routed"
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