Thursday, March 25, 2010

MPLS Interview Questions for CCNA and CCNP Engineers

After IGP and BGP questions, I prepared basic list of MPLS interview questions which could help you to clear your next level. In the up coming post, I will be covering switching. Below is the list of questions:-

1. What is the difference between VPN and MPLS?
2. What is MPLS and why it is being so popular in short time?
3. What is the protocol used by MPLS?
4. MPLS works on which layer?
5. What is the difference between P and PE router?
6. Can I make my PE router as P?
7. Two routers are having 4 equal cost links, how many ldp sessions will be established?
8. My LDP router id, OSPF router id and BGP router id is different, will it work to forward the traffic of customers or not?
9. What is Penultimate Hop Popping and why it is required? Which router performs the PHP function?
10. I am receiving aggregate label, what does it mean?
11. What are the different types of labels?
12. How to make customer route unique?
13. What is the difference between RD and RT?
14. Can I assign a same RD to two different customers?
15. Is RD travels in route update?
16. My customer is having three branches and all are attached to three different PEs, In this case can I use the different vrf names?
17. What is downstream on demand?
18. How to filter MPLS labels?
19. What is the default range of MPLS labels in Cisco routers? How to extend that range?
20. Without route reflector can I implement MPLS?
21. What is the difference between VPNv4 and IPv4 address family?
22. What is MP-iBGP? Can we use normal BGP in lieu of MP-iBGP?
23. What is LIB, LFIB?
24. What is CEF and without enabling CEF, can we make MPLS work?
25. I am receiving end to end customer routes on various PE but not able to ping those routes, what’s could be the problem?
26. What is explicit null and implicit null?
27. Default timers of LDP?
28. Does LDP require OSPF, IS-IS or BGP?
29. In neighbor discovery command, I am receiving only xmit, what does it mean?
30. What is transport address?
31. What is the RFC of MPLS?
32. Why MPLS is called multi protocol?
33. What is the difference between MPLS, SSL and IPSec?
34. I am using different vendor products and want to implement TDP, what type of challenges will you face?
35. Does MPLS support IPv6?
36. Can I use the existing IPv4 MPLS backbone for IPv6?
37. Define various troubleshooting commands in MPLS?
38. What is forward equivalence class aka FEC?
39. What is adjacency table?
40. Difference between MPLS IP and MPLS Label Protocol LDP command?
41. If MPLS get disable, will it harm my IGP or IPv4 traffic?
Click here for answers
42. What is MPLS-TP?
43. What is downstream and upstream router in MPLS? 44. Difference between MPLS and MPLS-TP?
45. How Does LDP Initializes?
46. What is Cell Mode MPLS Over ATM?
47. Difference Between VC Based Multiplexing And Logical Link Control Encapsulation in ATM?
48. Basics of ATM?
49. ATM is packet or circuit switching?
50. Is LDP Required for VPNv4 Labels?
51. What will happen if you see your PE loopback in vpnv4 table?
52. What is Bidirectional Forwarding Detection?
53. Different types of PseudoWire?
54. Modes of EoMPLS (Ethernet over MPLS)
55. What is L2VPN Over Metro Ethernet?
56. What is E-VPN(Ethernet VPN)?
57. what is FEC in traditional IP routing and MPLS?
58. How does CEF understand overlapping of ip addresses ?
59. What is the difference between Optimum, Fast and CEF Switching?
60. Advantages of MPLS.
61. Define CEF FIB table entries.

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allan316 said...

where have you gone buddy?

Luca Gervasi said...

Very nice articles (all the 3 published so far). I'm only ccna, many questions remains unsolved...what about publishing the answers too?



shivlu jain said...

Right now having very short time to post the answers. If you need any help please email I will reply to those.

shivlu jain said...

Answers are available on given link

-AFMK- said...

Nice articles..helped me a lot...


naitik said...

Fantastic job!!!!pls continue it for Networking Professional

Sudeep Goyal said...

Thanks. Very Helpful Questions. I also write about MPLS on my blog:

Anonymous said...

Answer 4: MPLS work in betwwen layer 2 & Layer 3. So you can say that MPLS workd on Layer 2.5

Arvind Kumar said...

Answer 6:
P router is Prover router. Generally in the core network of the provider. Don't have any information about customers routes. No need to run MP-BGP on P router. Used fr lable switching.
Whereas PE router is provider Edge router. The Router which itracte with customer router. Having all the customer routes. As clear from name it is an edge router and have connectivity to both custer edge router and the P router. Need to run MP-BGP on PE.
Also VRF is required on PE.

Arvind Kumar said...

Answer 3 :
MPLS use two protocols
1. LDP
2. TDP

TDP is the default one.
LDP is most famous and is used widely.

saurabh said...

you give very very basic answer of questions i think you should have to describe in to detail..Like you give answer of question (13) "What is the difference between RD and RT?"
Your answer is "RD is not an extended community where as RT is an extended community."
this is very very basic answer dude...