Interfaces for very large devices are not seen in the CAPC user interface when looking at the device on the Data Aggregator (Administration > Monitored Devices in the CAPC user interface). An example of a large device could be an Adtran device that has thousands of interfaces
The rest call made to retrieve the list of interfaces is to large for the system to handle. Here is an example of the Warning seen in the Data Aggregator's karaf.log:
WARN | 149915323-305150 | 2016-12-16 19:48:49,107 | WebApplicationExceptionMapper | pl.WebApplicationExceptionMapper 73 | xf.cxf-rt-frontend-jaxrs | | javax.ws.rs.WebApplicationException: java.lang.IllegalArgumentException: The estimated count of 213653 for endpoint ports exceeds the maximumn allowed by the mananger of 200000. To avoid risking the integrity of the server, we are unable to return the request XML.
The exact number that you put in should mimic the approximate count seen in the DA karaf.log, with the caveat that setting this to a high number can result in OutOfMemory errors.