ndp(1M) ndp(1M)
NAME
ndp - IPv6 Neighbor Discovery cache display and control
SYNOPSIS
host
interface]
interface] interval
interface] host
interface]
interface]
interface]
interface host hw_addr
filename
DESCRIPTION
The command displays and modifies the IPv6 Neighbor Discovery cache as specified in the IPv6 Neighbor Discovery (ND) protocol.
Options
recognizes the following options and arguments:
host Display the current Neighbor Discovery cache entries for the host specified by host, which is either a name present in the
hostname database (see hosts(4)), or an IPv6 address expressed in colon notation (see inet6(3N)).
Select the Neighbor Discovery cache entries for the specified
interface. There is no distinction between primary and secondary interfaces. Therefore, specifying is the same as speci-
fying
Display host addresses in IPv6 colon notation.
If this option is not specified, attempts to display host addresses symbolically first, and falls back to displaying the
host addresses in IPv6 colon notation if that failed.
Display all Neighbor Discovery cache entries.
Continuously display all Neighbor Discovery cache entries,
updated at each interval, measured in seconds.
Deletes Neighbor Discovery cache entries with
IP addresses that are not associated with local interfaces for the host specified by host.
Flushes all Neighbor Discovery cache entries with
IP addresses that are not associated with local interfaces. These are entries with the (local) flag set. Refer to the
section of this manpage for information about flags.
(Quiet) Do not write anything to standard output.
This option only applies to and options.
Display the prefix list in the Neighbor Discovery cache table.
The prefix list defines a set of IP address ranges that the host can reach. The prefix flags are for on-link, and for au-
tonomous. The on-link flag indicates that addresses with that prefix can be reached directly without going through a
router. The autonomous flag indicates that the prefix came from stateless autoconfiguration.
Flushes all autoconfigured addresses learned from prefixes
advertised by the Router Advertisement Messages.
Create a Neighbor Discovery cache entry for the
interface specified by interface, the host specified by host, and the hardware address (link-layer address) specified by
hw_addr. The hw_addr is specified as where each x is a hexadecimal digit.
If is specified, the entry is published, which means that this system will respond to Neighbor Solicitation for the speci-
fied "host" even though the host address is not its own. If is specified, it means that the published entry refers to an
anycast address. This parameter can only be specified when the parameter is specified.
Create Neighbor Discovery cache entries from the
specifications found in the file specified by filename. Each entry in this file specifies the interface, host, hw_addr,
and optionally the flag. For example, the content of this file can be:
The use of and options requires root privileges.
Contents
A Neighbor Discovery cache entry includes the following fields:
o host (neighbor's host name or IP address)
o hardware address (link layer address) of host
o interface name
o state
o flags
The state of an entry can be or
o An entry is in an state if address resolution is in progress and the hardware address of the neighbor has not been determined.
o An entry is in a state if the neighbor is known to have been reachable recently.
o An entry is in a state if the neighbor is no longer known to be reachable. However, no attempt has been made to verify its
reachability because no traffic has been sent to this neighbor.
o An entry is in a state if the neighbor is no longer known to be reachable, and traffic has recently been sent to the neighbor.
o An entry is in a state if the neighbor is no longer known to be reachable, and unicast Neighbor Solicitation probes have been
sent to verify reachability.
The flags can be (Deprecated), (Local), (Published), (Temporary), (Auto), or (anycast). A deprecated address can be used for receiving
packets, but it should not be used for sending packets because its validity is expected to expire soon. The local flag indicates that this
Neighbor Discovery cache entry corresponds to an interface on this host. The published flag indicates that the host will respond to Neigh-
bor Solicitations on this IPv6 address. The temporary flag indicates that the address has a randomly generated interface identifier which
changes over time. The autonomous flag indicates that the prefix for the address came from stateless address autoconfiguration. The any-
cast flag indicates that the address is an anycast address.
DIAGNOSTICS
returns a non-zero value to indicate errors. A zero return value indicates success.
EXAMPLES
The following output shows the local interfaces and the IP addresses assigned to them.
Name Mtu Address/Prefix Ipkts Opkts
lan1 1500 fe80::210:83ff:fef7:3a21/10 982 759
lan1:1 1500 fec0::9:210:83ff:fef7:3a21/64 0 0
lan3 1500 fe80::210:83ff:fef7:7a9d/10 0 0
lo0 4136 ::1/128 57 57
To display the entire Neighbor Discovery cache:
Destination Physical Address Interface State Flags
fe80::202:fdff:fe36:8720 0:2:fd:36:87:20 lan1 STALE -
fec0::9:210:83ff:fef7:3a21 0:10:83:f7:3a:21 lan1:1 REACHABLE LP
fe80::210:83ff:fef7:3a21 0:10:83:f7:3a:21 lan1 REACHABLE LP
fe80::210:83ff:fef7:7a9d 0:10:83:f7:7a:9d lan3 REACHABLE LP
To show Neighbor Discovery cache entries for a host:
Destination Physical Address Interface State Flags
fe80::210:83ff:fef7:3a21 0:10:83:f7:3a:21 lan1 REACHABLE LP
To show Neighbor Discovery cache entries for an interface:
Destination Physical Address Interface State Flags
fe80::210:83ff:fef7:7a9d 0:10:83:f7:7a:9d lan3 REACHABLE LP
To delete a Neighbor Discovery cache entries for a host and an interface:
fe80::202:fdff:fe36:8720 (fe80::202:fdff:fe36:8720) deleted.
To show the prefix list:
Prefix List Interface Valid Preferred Flags
Entries Lifetime Lifetime
fec0:0:0:9::/64 lan1 167 107 A
fe80::/10 lan1 inf inf LA
fe80::/10 lan3 inf inf LA
To add an entry in the Neighbor Discovery cache:
nodeb (2001::1) added.
Destination Physical Address Interface State Flags
fe80::210:83ff:fef7:7a9d 0:10:83:f7:7a:9d lan3 REACHABLE LP
2001::1 0:1:2:3:4:5 lan3 - -
To flush all remote entries:
nodea (fe80::202:fdff:fe36:8720) flushed.
nodeb (2001::1) flushed.
AUTHOR
was developed by HP.
SEE ALSO
hosts(4), inet6(3N), ndp(7P).
Neighbor Discovery for IP Version 6 (IPv6), RFC2461, Narten, Nordmark, Simpson.
IPv6 Stateless Address Autoconfiguration, RFC2462, Thomson, Narten.
ndp(1M)