As the blueprint goes, this is, in my opinion, the most vague topic to write about. It is dependent on the understanding of the topics, and how the changes will impact the existing network. I have skimmed through this really, with the intention of covering the topics in their actual topic sections. I am pretty used to evaluating impact - I seem to spend my entire life writing change orders and determining "disruptiveness".
1.2.a Evaluate proposed changes to a network
This is a difficult section to write a paragraph about, as it is based on the understanding of the core topics, analysing the proposed changes and deciding how they will impact / affect the existing network infrastructure. These will be covered in more detail in their specific sections.
1.2.a (i) Changes to routing protocol parameters
Could include things like metrics, additional routes, redistribution. How these changes will impact existing services, etc.
1.2.a (ii) Migrate parts of a network to IPv6
Involves looking at IPv6 transition mechanisms: 6to4 tunnels, Toredo, ISATAP, Dual Stack, etc. Impact on existing services, interoperability, etc.
1.2.a (iii) Routing protocol migration
Manipulating metrics, redistribution, administrative distances, etc.
1.2.a (iv) Adding multicast support
Selecting the right place for the RP – bottlenecks, bandwidth, optimisation.
1.2.a (v) Migrate spanning tree protocol
Interoperability between legacy and rapid spanning-tree’s, MST regions, etc.
1.2.a (vi) Evaluate impact of new traffic on existing QoS design
Evaluating existing utilisation, correct classification and marking, etc.