1.1.a Describe basic software architecture differences between IOS and IOS XE

1.1.a (i) Control plane and Forwarding plane
1.1.a (ii) Impact to troubleshooting and performances
1.1.a (iii) Excluding specific platform’s architecture

no longer monolithic kernel (a monolithic kernel runs it’s processes in the same memory space)

systems functions are abstracted out of the kernel  and into separate processes

has become more platform independent (Pi)

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps9442/ps11192/ps11194/QA_C67-622903.html

IOS XE accomplishes Control Plane / Data Plane separation through the introduction of the Forwarding and Feature Manager (FFM) and its standard interface to the Forwarding Engine Driver (FED). FFM provides a set of APIs to Control Plane processes. In turn, the FFM programs the Data Plane via the FED and maintains forwarding state for the system. The FED is the instantiation of the hardware driver for the Data Plane and is provided by the platform.

http://networkingnerd.net/tag/ios-xe/