Filters let you focus on specific traffic. If you want to check a problem between two particular devices, perhaps a computer and a printer, address filters can capture just the traffic between these two devices. If you are having a problem with a particular function on your network, a protocol filter allows you to focus on traffic related to that particular function.
Filters work by testing packets against the criteria specified in the filter. Packets whose contents meet these criteria match the filter. You can build filters to test for just about anything found in a packet: addresses, protocols, sub-protocols, ports, error conditions, and more. Filters are so easy to create in that you can often create a custom filter on-the-fly while analyzing suspect traffic on your network.
NOTE: Filters created from a connected Capture Engine are available to that Capture Engine only. If you are not connected to a Capture Engine and you create a filter, that filter is available for local captures only.