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The Internet Control Message Protocol (ICMP) control enables your
application to send and receive ICMP echo datagrams. These are a
special type of IP datagram which can be used to determine if a server
is reachable, as well as determine the amount of time it takes for
data to be exchanged with the local system. The ICMP control can also
be used to trace the route that data takes from the local system to the
server, which can be useful in determining why a connection to a
particular system may be experiencing higher latency than normal.
The following properties, methods and events are available for use
by your application:
Initialize
Initialize the control and validate the runtime license key for the
current process. This method is normally not used if the control is
placed on a form in languages such as Visual Basic. However, if the
control is being created dynamically using a function similar to
CreateObject, then the application must call this method to
initialize the component before setting any properties or calling any
other methods in the control.
Uninitialize
Unload the Windows Sockets library and release any resources that
have been allocated for the current process. This is the last method
call that the application should make prior to terminating. This is
only necessary if the application has previously called the
Initialize method.
Ping and TraceRoute
To determine if a server is reachable, your application can
send ICMP echo datagrams. You can also map the route between the local
system and the server by sending a series of echo datagrams to
each intermediate host. This is what the ping.exe and tracert.exe
command line utilities do, and you can emulate that functionality in
your own applications.
Echo
This is the simplest method you can use to send ICMP echo datagrams.
Specify the server, the size of the ICMP datagram you want to
send and the number of times you want to send it. The method will
return if the operation was successful along with information such as
the average number of milliseconds it took for the datagram to be
returned by the server.
TraceRoute
This method will map the route that data packets take from your local
system to a server. Whenever you send data over the Internet,
that data is routed from one computer system to another until it
reaches its destination. This method returns statistical information
about each system that the data is routed through, and the latency
between that system and the local host. For each intermediate host in
the route to the destination server, the OnTrace event will fire.
OnTrace
This event is generated when the TraceRoute method is called. The
event will fire for each intermediate host in the route from the
local system and the server.
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