Use route filtering on Chicago router to block the 10 1.5.0V24 network from coming in from the LA router.

Use route filtering on LA router To block the 10 1 5 074 network from getting propagated toward Chicago and New York.

Use route aggregation on LA router to summarize the 10.1.4 074.10.1.5.0*24,10.1.6.0/24. and 10.1.7.004 networks toward Chicago.

Use route dampening on LA router for the 10.1.5.074 network so that it does not get propagated when it (laps up and down)