When choosing a path target, keep in mind is that you should be trying to measure performance through the network. By design network equipment treats traffic differently depending on whether it needs to forward traffic or respond to it. ICMP falls under the latter case and so routers often return worse results than expected. It’s common to see lower capacity and sometimes data loss when targeting these devices directly. The attached image shows the difference between network equipment and end-stations targeted across a gigabit network. The end-stations report the expected capacity, while the network equipment is dubiously lower.

That said, AppNeta appliances are your best target candidate. Servers and workstations are good targets, but you’ll often see 70%+ of the expected bandwidth; this is due to the quality of the NIC, the network driver, and the behavior of the host operating system. In addition, Windows machines are suitable as targets only on paths up to 100 Mbps. Finally, there are cases in which you might choose to target network equipment, despite their poor capacity measurements: you might only be able to connect to the outside interface of a remote WAN router and no other devices beyond it, or you might want to know when a device stops responding.

A couple of additional notes:

  • Voice handset sometimes make good targets and sometimes not; it varies model to model. It’s generally safe to monitor them for connectivity, but sometimes high packet loss can register as connectivity loss.
  • To target workstations, the workstations must allow icmp responses. If symantec endpoint protection is in place, you’ll need to create an exception.

pathview-good-target.png

Target type

You should keep the default ‘auto’. The other target types are legacy.