c_ping

MIPS处理器的bootloader,龙芯就是用的修改过的PMON2

ping 	The ping command 憫bounces拻 a packet to and from a specified network host.

Format 	The format for this command is:

ping [-nqv] [-i wait]] [-s size] [-l preload] host

where:

-i wait 	Wait waitseconds between sending each packet. The default is
to wait for one second between each packet.

-l preload 	If preload is specified, ping sends that many packets as fast as
possible before falling into its normal mode of behavior.

-n 	Numeric output only. 	No attempt will be made to lookup symbolic
names for host addresses.

-q 	Quiet output. 	Nothing is displayed except the summary lines at
startup time and when finished.

-s size 	Specifies the number of data bytes to be sent. The default is 56,
which translates into 64 ICMP data bytes when combined with
the 8 bytes of ICMP header data.

-v 	Verbose output. 	ICMP packets other than ECHO_RESPONSE
that are received are listed. 憫Echo Replies拻 are displayed symbolically.

Functional
Description

The ping command is used to verify ether net network connections and
setup. It makes use of a feature of the 憫ICMP拻 protocol, which is used by
hosts and gateways for low-level administrative chores. Each ICMP host is
required to respond to an ECHO_REQUEST datagram with an
ECHO_RESPONSE. ECHO_REQUEST datagrams (憫pings拻) have an IP and
ICMP header, followed by a time and then an arbitrary number of 憫pad拻 bytes
used to fill out the packet. The command continues pinging until interrupted
by a Control-C.

When using ping for fault isolation, start by pinging 憫127.0.0.1拻 (a universal
self-address, by internet convention.) This verifies that at least the onboard
setup is workable. Then, hosts and gateways further and further away should
be 憫pinged拻. Round-trip times and packet loss statistics are computed. If
duplicate packets are received, they are not included in the packet loss calculation,
although the round trip time of these packets is used in calculating the
minimum/average/maximum round-trip time numbers. When the program is
terminated by a Control-C a brief summary is displayed.

Ping will report duplicate and damaged packets. Duplicate packets 憫should
never happen拻: they抎 have to be gateway problems. Tell your network manager.

Damaged packets (data doesn抰 look like it should) are serious cause for
alarm and often indicate broken hardware somewhere in the ping packet抯
path (in the network or in the hosts).