
Chapter 12 • IPv6 Internet Control Message Protocol (ICMPv6) 213
address for reasons other than congestion. (An ICMPv6 message
must not be generated if a packet is dropped due to congestion.)
Packet Too Big A Packet Too Big must be sent by a router in response to
a packet that it cannot forward because the packet is larger than the
MTU of the outgoing link. The information in this message is used
as part of the Path MTU Discovery process.
Time Exceeded If a router receives a packet with a Hop Limit of zero, or
a router decrements a packet’s Hop Limit to zero, it must discard the
packet and send an ICMPv6 Time Exceeded message with Code 0 to
the source ...