ping6
Test IPv6 network connectivity
TLDR
Ping a host
Ping a host only a specific number of times
Ping a host, specifying the interval in seconds between requests (default is 1 second)
Ping a host without trying to lookup symbolic names for addresses
Ping a host and ring the bell when a packet is received (if your terminal supports it)
SYNOPSIS
ping6 [options] destination
PARAMETERS
-c count
Stop after sending count ECHO_REQUEST packets.
-s packetsize
Specify the number of data bytes to be sent in the packets.
-i interval
Wait interval seconds between sending each packet.
-h hoplimit / -t hoplimit
Set the IPv6 hop limit for the packets.
-v
Verbose output.
-q
Quiet output, showing only summary lines.
-n
Numeric output only. No reverse DNS lookup for host addresses.
-D
Print timestamps before each line.
-M pmtudisc_option
Path MTU Discovery options (e.g., do, dont, probe).
-I interface_or_address
Specify the source interface or address to send packets from.
-L
Suppress loopback of multicast packets.
-P
Don't fragment packets (sets the 'Don't Fragment' bit).
-w timeout
Exit after timeout seconds, regardless of packets sent or received.
-W timeout
Time in seconds to wait for a reply for each packet.
DESCRIPTION
The ping6 command is the IPv6 equivalent of the traditional ping utility. It is used to diagnose the reachability of an IPv6 host on an Internet Protocol (IP) network and to measure the round-trip time for packets sent from the local host to a destination computer.
It operates by sending ICMPv6 Echo Request packets to the target host and listening for ICMPv6 Echo Reply packets. ping6 provides vital information such as packet loss percentage, minimum, average, and maximum round-trip times, which are crucial for identifying network performance bottlenecks, routing issues, or firewall configurations that might be blocking traffic over an IPv6 network.
CAVEATS
Root Privileges: May require root privileges for certain operations (e.g., opening raw sockets on older systems), though many modern Linux distributions allow non-root users to execute it.
Firewall Blocking: Firewalls (both host-based and network-based) can block ICMPv6 packets, leading to perceived packet loss or unreachable hosts, even if other traffic might pass.
Local Connectivity Only: Only measures connectivity from the local host; it doesn't indicate if other hosts can reach the target.
Packet Loss Causes: High packet loss can indicate network congestion, misconfiguration, or an unreachable host.
ICMPV6 ECHO MECHANISM
At its core, ping6 utilizes ICMPv6 Echo Request (Type 128) and Echo Reply (Type 129) messages. These messages are fundamental for network diagnostics, allowing a host to determine if another host is reachable and how long it takes for a packet to make a round trip.
OUTPUT INTERPRETATION
Understanding the output of ping6 is crucial. Key metrics include the round-trip time (min/avg/max), which indicates latency, and the packet loss percentage, which signals potential network congestion or reachability issues. Messages like 'Destination Unreachable' or 'Hop Limit Exceeded' provide further diagnostic clues.
HISTORY
The original ping utility was created by Mike Muuss in 1983. As IPv6 gained prominence and became essential for modern networking, the need for an equivalent diagnostic tool arose. ping6 was developed as part of the iputils package to provide identical functionality for IPv6 networks, ensuring consistency in network troubleshooting practices across both IP versions. Its development reflects the ongoing evolution and adoption of IPv6 globally.
