target

Defines an active-measurement target.

target <address> 
 
	[ <type> ]
 
	[ [ <rate> <unit> [ <port> ] ] 
 
	[ measure-type <mtype> ] 
 
	[ timeout <value> ]
 
	[ description <text> ]
 
	
 
no target <address> <type>
 

• address--hostname or IP address of the host to be probed
• type--protocol to be used; can be tcp, icmp, or traceprobe
• rate--value portion of probe frequency; positive, non-zero integer
• unit--unit portion of probe frequency; must be one of the following:
• per-second
• per-minute
• per-hour
• per-day
• port--port to be contacted on host
• mtype--how CNA should parcel out measurements among USTATs; must be one of the following:
• simultaneous
• round-robin
• value--number of milliseconds to wait for a response; range: 0 through 780000 (default: 3000)
• text--text of the description; can consist of any combination of alphanumerical characters, dash, underscore and space

Must be in active-measurement configuration mode (config-engine-active), which requires privileged-level access.

May be used multiple times within an active-measurement group configuration block.

Active measurements represent one of the means by which CNA obtains network traffic data. The system actively establishes contact with a remote host in order to obtain measurement data by opening and immediately closing a TCP session on the specified port.

This is in contrast with the User Traffic Test (UTT), where CNA waits for a web surfer to initiate contact and then measures the time it takes to respond to the user’s request for an image.

The values you set for the rate and unit parameters of the active-measurement target command determine the frequency of the active probes.

NOTE: If you are configuring a TCP probe, a port value must be specified either for the individual probe or the group, or the probe will fail. The output of the show statistics command for the am-scheduler process includes a configuration errors table which will note the lack of a port assignment.

The timeout value sets the number of seconds CNA will wait for a response from the target. If value is set to 0, CNA will not timeout on its own (though the underlying kernel will timeout in approximately 13 minutes). The timeout value is used by the outage-detection active-probe command in determining whether a prefix is experiencing an outage.

If you set mtype to simultaneous, CNA will contact the target through all service provider links simultaneously at each scheduled probe time. Round-trip traffic measurements can be compared directly and the fastest route observed empirically.

If you set mtype to round-robin, CNA will contact the target through a single service provider link at each scheduled probe time, proceeding through all links in round-robin fashion. This method places less demand on the target host, but it also produces fewer measurement points, and the measurements do not all represent the same moment in time.

For example, the following command, entered while in engine configuration mode, would create a probe using ICMP aimed at a target whose IP address is 192.168.121.10:

		CNA (config-engine)# active-measurement target 192.168.121.10 icmp 2 per-second
 

 

Default values were accepted for measurement type and timeout (ICMP probes don’t take a port assignment). This will cause CNA to send a probe to the target through every configured link twice every second (simultaneous measurement type).

See also the active-measurement group command.

Use the no form of the command to delete an active measurement probe.