ICMPv6 ECHO_REQUEST packets to network hosts
uses the ICMPv6 protocol's mandatory
datagram to elicit an
from a host or gateway.
(“pings”) have an IPv6 header, followed by an ICMPv6 header
formatted as documented in RFC 4443. The options are as follows:
- Stop after sending (and receiving)
ECHO_RESPONSE packets. If
count is 0, send an unlimited number of
- Set the
on the socket being used.
- Emit an audible beep (by sending an ASCII BEL character to
the standard error output) when no packet is received before the next
packet is transmitted. To cater for round-trip times that are longer than
the interval between transmissions, further missing packets cause a bell
only if the maximum number of unreceived packets has increased. This
option is disabled for flood pings.
- Emit an audible beep (by sending an ASCII BEL character to
the standard error output) after each non-duplicate response is received.
This option is disabled for flood pings.
- Flood ping. Outputs packets as fast as they come back or
one hundred times per second, whichever is more. For every
ECHO_REQUEST sent a period
(‘.’) is printed, while for every
ECHO_REPLY received a backspace is
printed. This provides a rapid display of how many packets are being
dropped. Only the super-user may use this option.
This can be
very hard on a network and should be used with caution.
- Specifies to try reverse-lookup of IPv6 addresses. The
ping6 command does not try reverse-lookup
unless the option is specified.
- Set the IPv6 hoplimit.
- Specifies the source address of request packets. The source
address must be one of the unicast addresses of the sending node, and must
- Wait wait seconds
between sending each packet. The default is
to wait for one second between each packet. This option is incompatible
with the -f option.
- Disable the loopback, so the transmitting host doesn't see
ICMP requests. For multicast pings.
- If preload is specified,
ping6 sends that many packets as fast as
possible before falling into its normal mode of behavior. Only the
super-user may use this option.
- By default, ping6 asks the
kernel to fragment packets to fit into the minimum IPv6 MTU.
-m will suppress the behavior in the
following two levels: when the option is specified once, the behavior will
be disabled for unicast packets. When the option is specified more than
once, it will be disabled for both unicast and multicast packets.
- Numeric output only. No attempt will be made to look up
symbolic names from addresses in the reply.
- Up to 16 “pad” bytes may be specified to fill
out the packet sent. This is useful for diagnosing data-dependent problems
in a network. For example, “-p ff” will cause the packet
sent to be filled with all ones.
- Quiet output. Nothing is displayed except the summary lines
at startup time and when finished.
- Specifies the number of data bytes to be sent. The default
is 56, which translates into 64 ICMP data bytes when combined with the 8
bytes of ICMP header data.
This option is ignored if any of the flags
- Set the routing table to be used for outgoing packets.
- Verbose output. All ICMP packets that are received are
- Specifies the maximum number of seconds to wait for
responses after the last request has been sent. The default is 10.
When using ping6
for fault isolation, it should
first be run on the local host, to verify that the local network interface is
up and running. Then hosts and gateways further and further away can be
“pinged”. Round-trip times and packet loss statistics are
computed. If duplicate packets are received, they are not included in the
packet loss calculation, although the round trip time of these packets is used
in calculating the round-trip time statistics. When the specified number of
packets have been sent (and received) or if the program is terminated with a
, a brief summary is displayed,
showing the number of packets sent and received, and the minimum, maximum,
mean, and standard deviation of the round-trip times.
This program is intended for use in network testing, measurement, and
management. Because of the load it can impose on the network, it is unwise to
during normal operations or from
will report duplicate and damaged packets.
Duplicate packets should never occur when pinging a unicast address, and seem
to be caused by inappropriate link-level retransmissions. Duplicates may occur
in many situations and are rarely (if ever) a good sign, although the presence
of low levels of duplicates may not always be cause for alarm. Duplicates are
expected when pinging a broadcast or multicast address, since they are not
really duplicates but replies from different hosts to the same request.
Damaged packets are obviously serious cause for alarm and often indicate broken
hardware somewhere in the ping6
packet's path (in
the network or in the hosts).
The (inter)network layer should never treat packets differently depending on the
data contained in the data portion. Unfortunately, data-dependent problems
have been known to sneak into networks and remain undetected for long periods
of time. In many cases the particular pattern that will have problems is
something that does not have sufficient “transitions”, such as
all ones or all zeros, or a pattern right at the edge, such as almost all
zeros. It is not necessarily enough to specify a data pattern of all zeros
(for example) on the command line because the pattern that is of interest is
at the data link level, and the relationship between what is typed and what
the controllers transmit can be complicated.
This means that if there is a data-dependent problem, a lot of testing will
probably have to be done to find it. It may be possible to find a file that
either cannot be sent across the network or that takes much longer to transfer
than other similar length files. This file can then be examined for repeated
patterns that can be tested using the -p
exits 0 if at least one reply is received,
and >0 if no reply is received or an error occurred.
works just like
the following will send ICMPv6 echo requests to dst.foo.com:
The following will send ICMPv6 echo requests to the link-local all-node
multicast address. The packet reaches all nodes on the network link attached
to the wi0 interface.
S. Deering, and M. Gupta,
Internet Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification, RFC
4443, March 2006.
first appeared in 4.3BSD
command with IPv6 support first appeared in
the WIDE Hydrangea IPv6 protocol stack kit.
is intentionally separate from