On 18 Mar 2002, at 21:12, Roberto Safora Romay wrote:

> To test the physical connection to an ip address you use ping ipaddress.
> What does ping stand for?
> Is it part of a particular set of commands?

  The "TCP/IP" protocol suite includes a number of subprotocols built
around some common concepts.  The simplest of these is one called
ICMP -- Internet Control Message Protocol.  ICMP consists of a set of
short, simple messages fopr relaying things like status information.
  One of the ICMP message fields is a "type" value, and two
particular simple types are "echo request" ("Please send me back a
message") and "echo reply" ("Here is the message you asled for").

  The Ping program sends an ICMP Echo Request message, and listens
for a corresponding ICMP Echo Reply.  Because ICMP is built on top of
the shared IP protocol core, a successful request and reply
demonstrated that the cabling is connected properly, that the network
interfaces are working and exchangind data, and that the IP routing
configurations between the "source" and "target" machines (in both
directions!) are working properly.  It's a good basic test of
networking connectivity.

  The Ping program is generally supplied (as an example and simple
diagnostic tool) by whoever implements the TCP/IP networking code.
In all recent versions of WIndows, this comes from Microsoft along
with the OS, so they supply a version of Ping ("ping.exe").  About
the only reason anyone would write their own Ping program any more
would be as an introductory exercise in programming using networks --
it's not a bad place to start on that.

  There is a claim that PING stands for "Packet InterNet Groper".
This was clearly made up after the fact.

  Note that when you bounce a sonar or radar echo off an object, the
object itself doesn't do anything.  In contrast, a pinged host must
actually receive the "echo request" message and process it, sending
back an "echo reply".  So there's a sense in which "ping" is more
like asking "Hello?  Are you there?" than it is like a searching
sonar.
  So in some online forums, "Ping Fred" is recognized as a shorthand
"computereze" way of saying "Hey Fred, if you're in the forum, please
send me back a message".  (In network protocol terms, this is
actually a bit more like ARP than like Ping, but users prefer the
sound of "Ping".)

  There are some other programs/commands that are also typically
provided with a TCP/IP protocol suite, such as traceroute
(tracert.exe -- which actually uses the same echo request/reply
messages, but works with some additional fields) and nslookup.  So
yes, there's a sense in which Ping is part of a set or group.

David Gillett

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