HP-UX Reference (11i v3 07/02) - 1M System Administration Commands A-M (vol 3)

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ifconfig(1M) ifconfig(1M)
arp (inet only) Enable the user of the Address Resolution Protocol in mapping
between network level addresses and link level addresses (default). If an
interface already had the Address Resolution Protocol disabled, the user
must "unplumb" the interface before it can be enabled for Address Resolu-
tion Protocol.
-arp (inet only) Disable the use of the Address Resolution Protocol. If an inter-
face already had the Address Resolution Protocol enabled, the user must
"unplumb" the interface before it can be disabled for Address Resolution
Protocol.
plumb Setup the Streams plumbing needed for TCP/IP for a primary interface
name. (See the Interface Naming subsection given below.). By default, the
plumb operation is done automatically when an IP address is specified for
an interface.
unplumb Tear down the Streams plumbing for a primary interface name. (See the
Interface Naming subsection given below.) Secondary interface does not
require "plumbing". A secondary IPv4 interface can be removed by assign-
ing an IP address of 0.0.0.0 to it. Remove a secondary IPv6 interface by
assigning an IP address of :: to it.
Interface Naming
The interface name associated with a network card is composed of the name of the interface (e.g.
lan or
snap ), the ppa number which identifies the card instance for this interface, and an optional IP index
number which allows the configuration of multiple IP addresses for an interface. For LAN cards, the inter-
face name
lan will be used to designate Ethernet encapsulation and
snap for IEEE 802.3 encapsulation.
The
nwmgr and lanscan commands can be used to display the interface name and ppa number of each
interface that is associated with a network card (see nwmgr(1M) and lanscan(1M)).
IPv4 and IPv6 interfaces can coexist over the same physical network interface device using the same nam-
ing scheme. IPv6 interfaces are configured using the "inet6" ifconfig subcommand. (See the IPv6 subsec-
tion given below.)
The tunnel interface names should be
iptu* for "IP6-in-IP" tunnels and 6to4 tunnels. Example:
iptu0, iptu1. The tunnel interface names should be ip6tu* for "IP-in-IP6" tunnels and "IP6-in-IP6"
tunnels. Example: ip6tu0, ip6tu1.
IP Index Number
Multiple IP addresses assigned to the same interface may be in different subnets. An example of an inter-
face name without an IP index number is lan0. An example of an interface name with a IP index number
is
lan0:1. Note: specifying lan0:0 is equivalent to lan0.
A primary interface is an interface whose IP index number is zero. A secondary interface is an interface
whose IP index number is non-zero.
Loopback Interface
The loopback interface (lo0) is automatically configured when the system boots with the TCP/IP software.
The IP address and netmask of the primary IPv4 loopback interface are 127.0.0.1 and 255.0.0.0, respec-
tively. The IP address and prefix of the primary IPv6 loopback interface are ::1 and 128 respectively. The
user is not permitted to change the address of the primary loopback interface (lo0:0). It is permissible to
assign other IP addresses to lo0 with non-zero IP index numbers (lo0:1, lo0:2, etc). This allows a system to
have a "system IP" address that is available as long as one interface remains usable.
Supernets
(inet only) A supernet is a collection of smaller networks. Supernetting is a technique of using the netmask
to aggregate a collection of smaller networks into a supernet.
This technique is particularly useful when the limit of 254 hosts per class C network is too restrictive. In
those situations a netmask containing only a portion of the network part may be applied to the hosts in
these networks to form a supernet. This supernet netmask should be applied to those interfaces that con-
nect to the supernet using the ifconfig command. For example, a host can configure its interface to
connect to a class C supernet, 192.6, by configuring an IP address of 192.6.1.1 and a netmask of 255.255.0.0
to its interface.
328 Hewlett-Packard Company − 3 − HP-UX 11i Version 3: February 2007