CCNP SP MPLS FAQ: MPLS VPN
Q1. What is a route distinguisher?
Q2. How is a packet that is coming from the CE router identified as to which VRF it belongs?
Q3. What is the purpose of RTs?
Q4. What is an RR group?
Q5. What is the BGP neighbor command with as-override used for?
Q6. When would you use different route distinguishers for routes of the same VPN?
Q7. What command should you configure on a Multi-VRF CE router that is running OSPF?
Q8. What three characteristics does an OSPF sham link have?
Answer: An OSPF sham link has the following characteristics:
Q9. Why do MPLS VPN packets have two MPLS labels?
Q10. Which BGP extended community can prevent routing loops from occurring in MPLS VPN networks?
Q11. How can overlapping IP addresses be supported between customer sites when MPLS VPN is deployed?
Q12. What routing information is contained within the global routing table on
Q13. The combination of the per VPN routing table and per VPN forwarding
Q14. What is a route target?
Q15. What is the purpose of the route target?
Q16. How are client VPN routes distributed across the service provider P network?
Q17. What is a route distinguisher (RD)?
Q18. What is a routing context?
Q19. Using the basic MPLS VPN mechanisms is it possible to have overlapping
Q20. How can the issue of overlapping IP addresses between different sites in an extranet be resolved?
Q21.What are the two different formats that can be used for the route distinguisher (RD)?
Q22. Does the RD have any special meaning for BGP?
Q23: How are loops prevented between VPN client sites when these sites are multihomed to the backbone?
Q24. What type-code is used for the route target within the Extended Community attribute?
Q25. What must you configure to enable static routing, or routing information learned through RIP version 2 or OSPF to be advertised between PE routers?
Q26. Which specific BGP capability must be supported between PE routers to enable the successful exchange of VPNv4 prefix information?
Q27. What information is carried within the MP_REACH_NLRI attribute?
Q28. During periods of convergence why does a cell mode MPLS
Q29. How often does the import scanner run on a PE router?
Q30. Why is it necessary to be careful when adjusting the scanner interval from its default of 60 seconds?
Q31. Can a single BGP session carry routes for multiple address families?
Q32. If only VPNv4 routes must be carried across a BGP session, which command prevents the advertisement of IPv4 routes?
Q33. Describe the functionality of a route reflector.
Q34. Describe the main benefit of route-reflector partitioning.
Q35. Describe the ORF capability.
Q36. In an IP routed backbone why is it necessary for P routers to hold full
Q37. How does the full routing requirement change with the introduction of MPLS into the core?
Q38. What are the two advantages to carrying external routing in BGP rather than in the service provider IGP?
Q39. When running OSPF, why is it necessary for the PE loopback addresses to be a /32 host address?
Q40. Why can’t PE loopback addresses be summarized within the backbone?
Q41. During the PE import process, what can be used to filter out certain routes?
Q42. Is it possible to advertise routes from the same VRF with different RT values?