2.3.8 Stage five: Integration of router Lille in the IS-IS domain
As per design prerequisite, router Lille needs to be connected to both router Livorno and router Havana via an IS-IS Level 1 adjacency without modifying its area identifier. Router Livorno'?, Net-ID includes Area ID 49.0003, but router Havana was previously in Area 49.0001.
Also, prefix leaking is needed for optimal routing; the exact same policy defined in Listing 2.108 can be used for this. This policy is already implemented in router Havana for the internal Area 49.0001, but needs to be addressed in router Livorno. Also, this system is part of a domain with a different reference-bandwidth, and it would be preferable to adapt metric costs to the same value as router Havana to have optimal routing from remote end points.
Router Lille is a very sensitive system with direct connections to the NOC and to all management systems, and as a protection mechanism, no default route should be installed as a consequence of any IS-IS ATTached bits.
On top of all these obvious requirements, another subtle situation needs careful thought: router Havana is already L1L2 system for another LI area with different authentication settings than the final key values. Authentication keys for all IS-IS PDUs cannot be configured on a per-area basis, but on a per-level basis, which means that modifying these values would have further implications inside the domain "Mistral". Effectively, because both Area 49.0001 and Area 49.0003 are included ...