Editing Ping (networking utility) (section)

===ICMPv6 packet transported with IPv6===

An ICMP packet transported with IPv6 looks like this.
{{APHD|start|title=IPv6 datagram}}
{{APHD|0|bits1=4|field1=Version|value1=6|bits2=8|field2=Traffic class|bits3=20|field3=Flow label}}
{{APHD|4|bits1=16|bits2=8|bits3=8|field1=Payload length|field2=Next header|value2=58|hint2=Set to 58 to indicate ICMPv6.|field3=Hop limit}}
{{APHD|8|bits1=128|field1=Source address}}
{{APHD|24|bits1=128|field1=Destination address}}
{{APHD|end}}
{{APHD|start|header=no|title=ICMPv6 ''Echo Request'' packet}}
{{APHD|40|bits1=8|field1=Type|value1=128|background1=mistyrose|bits2=8|field2=Code|value2=0|background2=mistyrose|bits3=16|field3=Checksum|background3=mistyrose}}
{{APHD|44|bits1=16|field1=Identifier|background1=mistyrose|bits2=16|field2=Sequence number|background2=mistyrose}}
{{APHD|48|bits1=0|field1=(Payload)|background1=linen}}
{{APHD|end}}
;{{APHD|def|name=Type|length=8 bits|text=Set to 128 to indicate 'Echo Request'.}}
;{{APHD|def|name=Identifier|length=16 bits|text=Can be used by the client to match the reply with the request that caused the reply.}}
;{{APHD|def|name=Sequence number|length=16 bits|text=Can be used by the client to match the reply with the request that caused the reply.}}
;{{APHD|def|name=Checksum|length=16 bits|text=The checksum is calculated from the ICMP message (starting with the ''Type'' field), prepended with an IPv6 ''pseudo-header''.{{Ref RFC|4443}}}}
;{{APHD|def|name=Payload|length=variable length|text=Optional. Payload for the different kind of answers; can be an arbitrary length, left to implementation detail.}}
Most Linux systems use a unique ''Identifier'' for every ping process, and ''Sequence number'' is an increasing number within that process. Windows uses a fixed ''Identifier'', which varies between Windows versions, and a ''Sequence number'' that is only reset at boot time.

The ''Echo Reply'' is returned as:
{{APHD|start|header=no|title=ICMPv6 ''Echo Reply'' packet}}
{{APHD|40|bits1=8|field1=Type|value1=129|background1=mistyrose|bits2=8|field2=Code|value2=0|background2=mistyrose|bits3=16|field3=Checksum|background3=mistyrose}}
{{APHD|44|bits1=16|field1=Identifier|background1=mistyrose|bits2=16|field2=Sequence number|background2=mistyrose}}
{{APHD|48|bits1=0|field1=(Payload)|background1=linen}}
{{APHD|end}}
;{{APHD|def|name=Type|length=8 bits|text=Set to 129 to indicate 'Echo Reply'.}}
;{{APHD|def|name=Identifier|length=16 bits|text=Copied from the ''Echo Request'' and returned.}}
;{{APHD|def|name=Sequence number|length=16 bits|text=Copied from the ''Echo Request'' and returned.}}
;{{APHD|def|name=Payload|length=variable length|text=Optional. Payload is copied from the ''Echo Request'' and returned.}}