if_edsc(4) [debian man page]

EDSC(4) 						   BSD Kernel Interfaces Manual 						   EDSC(4)

NAME

     edsc -- Ethernet discard network interface

SYNOPSIS

     device edsc

DESCRIPTION

     The edsc interface is a software discard mechanism which may be used for performance analysis and software testing.  It imitates an Ethernet
     device, which allows for its use in conjunction with such drivers as if_bridge(4) and vlan(4).

     As with other network interfaces, an edsc interface must have network addresses assigned for each address family with which it is to be used.
     These addresses may be set or changed with the SIOCSIFADDR ioctl(2) or ifconfig(8) utility.

     Each edsc interface is created at runtime using interface cloning.  This is most easily done with the ifconfig(8) create command or using the
     cloned_interfaces variable in rc.conf(5).

SEE ALSO

     ioctl(2), arp(4), if_bridge(4), inet(4), intro(4), vlan(4), rc.conf(5), arp(8), ifconfig(8)

HISTORY

     The edsc device was derived from the disc(4) device and first appeared in FreeBSD 6.3.  This manpage was adapted from disc(4).

CAVEATS

     Since outgoing packets are just discarded by edsc, ARP requests stay unreplied.  Consequently, an IP packet cannot be sent via edsc until a
     static arp(4) entry is created for its next hop using arp(8).

     Initially an edsc interface has a zero link level address.  It can be changed with ifconfig(8) lladdr if needed.

BSD
								  March 25, 2007							       BSD

LO(4)                                                      BSD Kernel Interfaces Manual                                                      LO(4)

NAME

     lo -- software loopback network interface

SYNOPSIS

     device loop

DESCRIPTION

     The loop 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 or changed with the SIOCSIFADDR ioctl(2).  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 hard-
     ware 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.

DIAGNOSTICS

     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.

SEE ALSO

     inet(4), intro(4)

HISTORY

     The lo device appeared in 4.2BSD.  The current checksum generation and validation avoidance policy appeared in FreeBSD 8.0.

BSD                                                               March 15, 2009                                                               BSD