TCP/IP Management Programming Manual

Commands and Responses
HP NonStop TCP/IP Management Programming Manual—529636-001
6-92
STATISTICS Command
specified in the header. This error, usually caused by a noisy link, is rarely
reported because the checksum routine also detects this problem.
ZSTATS-ICMP-REFLECT
is the number of ICMP packets received by the ICMP Layer of the TCP/IP
subsystem during the sample period that have been sent a response. Note that
not all ICMP packets require a response.
ZSTATS-ICMP-IN-HIST
is the input histogram of ICMP messages recorded during the sample period.
This histogram indicates the number of each type of ICMP message that the
TCP/IP subsystem received from the network. Statistics are maintained in this
histogram for these ICMP messages:
Type 0 is the Echo Reply message.
This ICMP message is the reply to the Echo (8) message.
Essentially, an Echo Reply message is just the original Echo
message with the type changed from eight to zero and the
destination and source addresses reversed. The data returned in
the Echo Reply message is the same as that sent in the Echo
message.
The receipt of an Echo Reply message informs the local host that
the remote host is still alive. The data returned also gives the local
host a means of testing the integrity of the link.
Type 3 is the Destination Unreachable message.
A Destination Unreachable message is sent to the TCP/IP
subsystem when another host or gateway determines that a
destination host or port is unreachable. This message can be
caused by these reasons: either there is no route to the
destination or the route to the destination has gone down, a
nonexistent address has been specified, the process listening on
the port has gone down, the destination host has crashed, or
fragmentation is needed but the Don’t Fragment flag is set.
Type 4 is the Source Quench message.