software loopback network interface
interface is a software loopback
mechanism which may be used for performance analysis, software testing, and/or
local communication. As with other network interfaces, the loopback interface
must have network addresses assigned for each address family with which it is
to be used. These addresses may be set with the appropriate
commands for corresponding address
families. The loopback interface should be the last interface configured, as
protocols may use the order of configuration as an indication of priority. The
loopback should never
be configured first unless
no hardware interfaces exist.
If the transmit checksum offload capability flag is enabled on a loopback
interface, checksums will not be generated by IP, UDP, or TCP for packets sent
on the interface.
If the receive checksum offload capability flag is enabled on a loopback
interface, checksums will not be validated by IP, UDP, or TCP for packets
received on the interface.
By default, both receive and transmit checksum flags will be enabled, in order
to avoid the overhead of checksumming for local communication where data
corruption is unlikely. If transmit checksum generation is disabled, then
validation should also be disabled in order to avoid packets being dropped due
to invalid checksums.
- lo%d: can't handle af%d.
- The interface was handed a message with addresses formatted in an
unsuitable address family; the packet was dropped.
device appeared in
. The current checksum generation and validation
avoidance policy appeared in FreeBSD 8.0