300-410 ENARSI: Implementing Cisco Enterprise Advanced Routing and ServicesDemo

By Cisco · Question Mode

QuestionQ605

Layer 3 Technologies

Following routing-policy changes, the router in AS 45123 has been observed serving as a transit AS router for several service providers.

Which configuration ensures that the branch router in AS 45123 advertises only its local networks to every SP neighbor?

  • A
  • B
  • C
  • D
Explanation

The ^$ AS-path regular expression matches an empty AS_PATH, which identifies locally originated BGP routes. Applied outbound with neighbor SP-Neighbors filter-list 1 out, it permits only local networks and filters learned routes, so the router cannot provide transit advertisements between service providers.

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