H-4
Compaq ServerNet II PCI Adapter and Switch Installation Guide
Echo Test
The echo test verifies that normal traffic can pass through the ServerNet II SAN. "Normal"
means that standard ServerNet II packets, like those used for your applications, are used
for the test.
If the echo tests run successfully, your local host application can communicate with services or
other application components running elsewhere in the SAN.
How the Echo Test Works
The basic concept of the echo test is that the local host says “Hello, Are you there” to the
Remote Node (target); the target node responds with “Yes, I am here,” as illustrated
in Figure H-3.
Figure H-3. Basic Concept of the Echo Test
More precisely, the local host says, "I am sending you some data. Please send it back to me."
The target node is expected to respond (echo) with "Here is the data you wanted me to send to
you," as illustrated in Figure H-4.
Figure H-4. Local Host and Target Node Communications
The test is successful when the target node returns the correct data. The test fails if no answer is
received (time-out error), or if the returned data is different from the data that was sent.
Local Host
Computer
Remote Node
ServerNet
Network
Yes, I am here.
Are you there?
Local Host
Computer
Remote Node
ServerNet
Network
I am sending you some data,
please send it back to me.
Here is the data you wanted me to
send you.