Cisco Systems OL-11291-01 manual Passive Mode

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.

	User Guide for Internetwork Performance Monitor
A-10	OL-11291-01