user manual

A-10
User Guide for Internetwork Performance Monitor
OL-11291-01
Appendix A IPM FAQs and Troubleshooting Tips
IPM FAQs
The steps in the Active mode are:
1. The client opens a control channel (port 21) to the server and tells the server the port number to
respond on. This port number is a randomly determined port greater than 1023.
2. The server receives this information and sends the client an acknowledgement “OK” (ack). The
client and server exchange commands on this control connection.
3. When the user requests a directory listing or initiates the sending or receiving of a file, the client
software sends a “PORT” command that includes a port
number > 1023 that the client wishes the server to use for the data connection.
4. The server then opens a data connection from port 20 to the client's port number, as provided to it
in the “PORT” command.
Passive Mode
In passive FTP, the client opens the data sessions, using a port number supplied by the server. This mode
of operation is assumed to be more secure because all the connections are being initiated from the client,
so there is less chance that the connection will be compromised. The reason it is called passive is that
the server performs a “passive open.”
The steps in the Passive mode are:
1. In passive FTP, the client opens a control connection on port 21 to the server, and then requests
passive mode through the use of the “PASV” command.
2. The server agrees to this mode, and then selects a random port number (>1023). It supplies this port
number to the client for data transfer.
3. The client receives this information and opens a data channel to the server assigned port.
Q. Does IPM receive traps?
A. No. IPM does not receive traps. You can configure IPM to raise a trap when a threshold
violation/timeout occurs. However, you should configure a separate NMS to receive and process
these traps.
Q. How do I set SNMP views for the Write community string?
A. To set SNMP views for the Write community string, you need to have the following configuration
on the device:
snmp-server view <view-name> system included
snmp-server view <view-name> ciscoRttMonMIB included
snmp-server community <comm-string> view <view-name> RW
exit
write term
<view-name> can be any character string.
<comm-string> should be provided as the write community string in the source GUI of
IPM.
Q. Can I get historical statistics that are less than an hour?
A. No. It is not possible to get historical statistics which are less than 1 hour.