TCP/IP Management Programming Manual

Commands and Responses
HP NonStop TCP/IP Management Programming Manual—529636-001
6-90
STATISTICS Command
A Destination Unreachable message is sent to the source host by
the TCP/IP subsystem (functioning as a host) when the
destination host or port is unreachable. This message is sent by
the TCP/IP subsystem (functioning as a gateway) when the
destination network or host is unreachable, fragmentation is
needed and the Don’t Fragment flag is set, or the source route
failed.
Type 4 is the Source Quench message.
The TCP/IP subsystem sends this message to the source host to
indicate that the TCP/IP subsystem is receiving datagrams more
quickly than it can process them. When the source host receives
this message, it should reduce the rate at which it is sending the
datagrams.
Type 5 is the Redirect message.
The TCP/IP subsystem (functioning as a gateway) sends this
message to the source host to indicate that there is a shorter path
to the destination through another gateway.
Type 8 is the Echo message.
This ICMP message is sent from the source address to the
destination address. An Echo Reply message containing the same
data is expected from the destination address.
Type 11 is the Time Exceeded message.
The TCP/IP subsystem (functioning as a gateway) sends this
message to notify the source host that the time-to-live field is zero
and the gateway has discarded the datagram. The TCP/IP
subsystem (functioning as a destination host) sends this message
if it cannot reassemble a fragmented datagram within the time limit
because fragments are missing. The TCP/IP subsystem discards
the datagram.
Type 12 is the Parameter Problem message.
The TCP/IP subsystem (functioning as a host or gateway) sends
this message to notify the source host that one of its datagrams
has been discarded because the header parameters are incorrect.
Type 13 is the Timestamp message.
The TCP/IP subsystem (functioning as a host or gateway) sends
this message to indicate the time it last handled the message
before sending it.
Type 14 is the Timestamp Reply message.