MPLS INTERVIEW QUESTIONS

  • Define the term FEC in MPLS.
  • Why is it necessary to enable CEF before running MPLS.
  • Two MPLS peers not able to for LDP neighborship. What are probable causes?
  • Which entity imposes label on the PE if the packet arrives unlabelled on it.
  • Explain the two types of Label Space. Per Platform and Per Interface.
  • What is OSPF SHAM-Link. Explain its use.
  • What is MP-BGP? Can we use normal BGP to run an MPLS VPN?
  • Can we assign a same RD to two different customers?
  • Customer is distinguished by an RD or an RT?
  • In control plane, how MP-BGP advertises the VPNv4 Label to its peers?
  • What is difference b/w Implicit-null and Explicit Null?
  • Explain the process of LDP neighborship forming?
  • Explain the difference b/w Process, Fast-Switching, Optimum-Switching and CEF Switching.
  • Name few other protocols that can generate and distribute labels besides LDP.
  • Explain various methods of Inter-AS communication.
  • What is difference b/w Inter-AS communication and CSC?
  • What is MPLS LDP Sync?  What is its benefit in MPLS VPN.
  • Do RD value travel in an MP-BGP update?
  • What is difference b/w an Aggregate label and Unlabbeled terms?
  • What is difference b/w Down-bit and Domain-Tag when we use OSPF as CE-PE protocol.
  • Explain the terms “Allow-as in”, “as-override” with the help of an example.
  • How can you refrain an RR router to not participate in Data Plane and only be used for Control Plane Communication.
  • Explain the use of commands “no bgp default ipv4-unicast” and “no bgp default route-target filter”.
  • Two PE nodes are advertising the vpnv4 routes using an RR but both PE cannot see/learn the remote-routes(advertised by 2nd PE) in their routing table even when they belong to same customer and RT values are correctly exported and imported. Explain the possible causes.