customer
Click on the red underlined text to get to the source
... traffic entering their networks that is coming from a source
address not legitimately in use by the customer network. The
filtering includes but is in no way limited to the traffic ...
... However, unless ingress filtering (or at least, a limited subset of
it) has been deployed at every border (towards the customers, peers
and upstreams) -- blocking the use of your own addresses as source
addresses ...
...
When a routing protocol is not being used, but rather the customer
information is generated from databases such as Radius, TACACS ...