Disclaimer: This blog series aims to use a visualized approach, a new way to describe designs in over simplified manner, where diagrams and figures are mainly used to explain this topic. (there is nothing better than diagrams and figures to explain designs)!
The previous blog “BGP Path Selection – Visualized Case Study-” covered some foundational BGP path selection options , this blog will take it a step further to cover more complicated BGP polices and path selection considerations. keep in mind this is not a best practice or only way of achieving the case study requirements, as the selection of the policy and BGP attributes always influenced by the actual scenario and intended goal. that being said, you should always keep it simple and avoid complex polices where applicable.
Structuring the BGP policy model and application
ISP/AS 500 establish a mapping between customer configurable community values and the corresponding local preference values within the provider network.
Practically, what are the limitations/implications of using AS_Prepending toward the Internet/ISPs?
In case of node F(AS 300) failure:
BGP community value 600:603 is an example of tagging certain prefixes with a BGP community value to control its propagation across BGP domains.
as mentioned earlier, always consider the simplest solution and ensure it offers enough flexibility to add and change prefixes in the future with minimal configurations.