ping6

by Chris Kranz on Jul.07, 2009, under Manual Pages

NAME

ping6 – send ICMPv6 ECHO_REQUEST packets to network hosts

ping6 [ -dHnNqRvw ] [ -a addrtype ] [ -b bufsize ] [ -c count ] [ -h hoplimit ] [ -I interface ] [ -i wait ] [ -l preload ] [ -p pattern ] [ -P policy ] [ -S sourceaddr ] [ -s packetsize ] [ hops... ] host

DESCRIPTION

ping6 uses the ICMPv6 protocol’s mandatory ICMP6_ECHO_REQUEST datagram to elicit an ICMP6_ECHO_REPLY from a host or gateway. ICMP6_ECHO_REQUEST datagrams (“pings”) have an IPv6 header, and ICMPv6 header formatted as documented in RFC2463.

OPTIONS

-a: addrtype

Generate ICMPv6 Node Information Node Addresses query, rather than echo-request. addrtype must be a string constructed of the following characters.

a: requests all the responder’s unicast addresses. If the charater is ommited, only those addresses which belong to the interface which has the responder’s address are requests.

c: requests responder’s IPv4-compatible and IPv4-mapped addresses.

g: requests responder’s global-scope addresses.

s: requests responder’s site-local addresses.

l: requests responder’s link-local addresses.

A: requests responder’s anycast addresses. Without this character, the responder will return unicast addresses only. With this character, the responder will return anycast addresses only. Note that the specification does not specify how to get responder’s anycast addresses. This is an experimental option.

-b: bufsize

Set socket buffer size.

-c: count

Stop after sending (and receiving) count ECHO_RESPONSE packets.

-d: Set the SO_DEBUG option on the socket being used.

-H: Specifies to try reverse-lookup of IPv6 addresses. The ping6 command does not try reverse-lookup unless the option is specified.

-H: hoplimit

Set the IPv6 hoplimit.

-I: interface

Source packets with the given interface address. This flag applies if the ping destination is a multicast address, or link-local/site-local unicast address.

-i: wait

Wait wait seconds between sending each packet. The default is to wait for one second between each packet.

-l: preload

If preload is specified, ping sends that many packets as fast as possible before falling into its normal mode of behavior.

-n: Numeric output only. No attempt will be made to lookup symbolic names for host addresses.

-N: Probe node information multicast group (ff02::2:xxxx:xxxx). host must be string hostname of the target (must not be a numeric IPv6 address). Node information multicast group will be computed based on given host and will be used as the final destination. Since node information multicast group is a link-local multicast group, destination link needs to be specified by -I option.

-p: pattern

You may specify up to 16 “pad” bytes to fill out the packet you send. This is useful for diagnosing data-dependent problems in a network. For example, “-p ff” will cause the sent packet to be filled with all ones.

-Q: flags, ping6 prints out any ICMP error messages caused by its own ECHO_REQUEST messages.

-P: policy

policy specifies IPsec policy to be used for the probe.

-q: Quiet output. Nothing is displayed except the summary lines at startup time and when finished.

-R: Make the kernel believe that the target host (or the first hop if you specify hops) is reachable, by injecting upper-layer reachability confirmation hint. The option is meaningful only if the target host (or the first hop) is a neighbor.

-S: sourceaddr

Specifies the source address of request packets. The source address must be one of the unicast addresses of the sending node. If the outgoing interface is specified by the -I option as well, sourceaddr needs to be an address assigned to the specified interface.

-s: packetsize

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. You may need to specify -b as well to extend socket buffer size.

-v: Verbose output. ICMP packets other than ECHO_RESPONSE that are received are listed.

-w: Generate ICMPv6 Node Information FQDN query, rather than echo-request. -s has no effect if -w is specified.

-W: Same as -w , but with old packet format based on 03 draft. This options is present for backward compatibility. -s has no effect if -w is specified.

hops IPv6 addresses for intermediate nodes, which will be put into type 0 routing header.

host: IPv6 adddress of the final destination node.

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 should be “pinged” . Roundtrip 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 SIGINT, 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 use ping6 during normal operations or from automated scripts.

NOTES

There have been many discussions on why we separate ping6 and ping. Some people have argued that it would be more convenient to uniform the ping command for both IPv4 and IPv6. The followings are an answer to the request.

From a developer’s point of view: since the underling API is totally different between IPv4 and IPv6, we would end up having two types of code base. There would actually be less benefit to uniform the two commands into a single command from the developer’s standpoint.

From an operator’s point of view: unlike ordinary network applications like remote login tools, we are usually aware of address family when using network management tools. We do not just want to know the reachability to the host, but want to know the reachability to the host via a particular network protocol such as IPv6. Thus, even if we had a unified ping command for both IPv4 and IPv6, we would usually type a -6 or -4 option (or something like those) to specify the particular address family. This essentially means that we have two different commands.

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