Routers R1 through R4 in the diagram have established IS-IS adjacencies. Router R1 is L1/L2 and is the DIS of its two broadcast interfaces. How many LSPs will it generate?
Router R1 is configured as L1/L2, meaning it is part of both Level 1 and Level 2 IS-IS routing areas. This means R1 will generate two types of LSPs:
Level 1 LSP (for the local area 49.0001) to advertise its local topology to other Level 1 routers.
Level 2 LSP (for the backbone area 49.0002) to advertise the global network topology to Level 2 routers.
R1 also has two broadcast interfaces, and as the Designated Intermediate System (DIS) on these interfaces, it will generate an LSP for each interface (one per broadcast link).
This results in three total LSPs:
A Level 1 LSP for the local area (49.0001).
A Level 2 LSP for the backbone area (49.0002).
An LSP for each of the two broadcast interfaces, which may include interface-related topology information.
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