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MPLS VPN Questions 2

Here you will find answers to MPLS VPN Questions – Part 2

Question 1

When configuring Internet access from a MPLS VPN using a separate subinterface, which two configurations are required on the PE router? (Choose two)

A. Use the ip vrf forwarding command on the subinterface that is used for MPLS VPN access.
B. Use the ip vrf forwarding command on the subinterface that is used for Internet access.
C. The CE router is configured as a BGP neighbor in both the global BGP process and inside the VPN in the VRF.
D. The PE-to-CE VPN and Internet routing are configured using two separate address-family ipv4 vrf commands, one for VPN routing and one for Internet routing.


Answer: A C

Question 2

When configuring Internet access using a separate MPLS VPN, which three statements are correct? (Choose three)

A. The Internet backbone is separate from the MPLS VPN backbone.
B. Two dedicated physical or logical links between the PE and the CE routers are required.
C. An Internet gateway is connected as a CE router to the MPLS VPN backbone.
D. An Internet gateway shall insert full Internet routing into the Internet VPN to achieve optimal routing.
E. The customer’s Internet access is enabled by combining the Internet VPN with the Customer VPN using overlapping VPN topology.


Answer: A C E

Question 3

BGP is used as the CE-PE routing protocol in an MPLS VPN. The customer routes are successfully propagated from the CE router to the ingress PE router, but they are not showing up on the egress PE router. What is the most likely cause of the problem?

A. There is a BGP-to-MPBGP redistribution error on the ingress PE router. 
B. There is a MPBGP-to-BGP redistribution error on the egress PE router.
C. One of the P routers is performing route summarization, breaking the path between the ingress and the egress PE routers into two LSPs. 
D. RTs attached to the CE routes exported by the ingress router are not matched by at least one of the import RTs on the egress PE router. 
E. A route reflector is used to propagate the routes from the ingress PE router to the egress PE router, thus breaking the LSP


Answer: D

Question 4

Refer to the exhibit and the following connectivity requirements. Which type of MPLS VPN is being implemented?


Sites CE1A and CE1B require connectivity to each other.
Sites CE2A and CE2B require connectivity to each other.
Site CE1C requires connectivity to sites CE1A, CE1B, CE3A, and CE3B.
Site CE2C requires connectivity to sites CE2A, CE2B, CE3A, and CE3B.
Sites CE3A and CE3B require connectivity to each other and to CE1C and CE2C.

A. central services MPLS VPN
B. overlapping MPLS VPN
C. simple VPN
D. combinations of overlapping and central services MPLS VPN
E. combinations of simple and central services MPLS VPN


Answer: D

Question 5

Refer to the exhibit. Which two of these statements are correct? (Choose two)


A. Router C will aggregate the address and advertise only the summary address to its neighbors.
B. Router C will advertise the prefix and all of the more specific prefixes.
C. Router C cannot aggregate the prefix if it does not have a more specific prefix in its BGP table.
D. To aggregate the prefix, router C must originate that prefix from within AS 300.
E. Router C will only aggregate the prefix for any updates it is sending to AS 200.


Answer: B C

Categories: BGP + MPLS 642-691 Exam Tags:
  1. lostpacket
    August 7th, 2011 at 11:24 | #1

    Please provide some more explanations.

    And do you have some reference for question 4? This topology and requirements are mentioned also in other question. Could you provide VRFs with RT which meets this criteria?


  2. Dylan
    January 19th, 2012 at 15:01 | #2

    Here is some explaination for Question 5


    To create an aggregate entry in a Border Gateway Protocol (BGP) or multiprotocol BGP database, use the aggregate-address command in address family or router configuration mode. To disable this function, use the no form of this command.

    aggregate-address address mask [as-set] [summary-only] [suppress-map map-name] [advertise-map map-name] [attribute-map map-name]

    no aggregate-address address mask [as-set] [summary-only] [suppress-map map-name] [advertise-map map-name] [attribute-map map-name]

    Usage Guidelines

    You can implement aggregate routing in BGP and multiprotocol BGP either by redistributing an aggregate route into BGP or multiprotocol BGP, or by using this conditional aggregate routing feature.

    Using the aggregate-address command with no keywords will create an aggregate entry in the BGP or multiprotocol BGP routing table if any more-specific BGP or multiprotocol BGP routes are available that fall in the specified range. The aggregate route will be advertised as coming from your autonomous system and will have the atomic aggregate attribute set to show that information might be missing. (By default, the atomic aggregate attribute is set unless you specify the as-set keyword.)

    Using the as-set keyword creates an aggregate entry using the same rules that the command follows without this keyword, but the path advertised for this route will be an AS_SET consisting of all elements contained in all paths that are being summarized. Do not use this form of the aggregate-address command when aggregating many paths, because this route must be continually withdrawn and reupdated as autonomous system path reachability information for the summarized routes changes.

    Using the summary-only keyword not only creates the aggregate route (for example, 10.*.*.*) but also suppresses advertisements of more-specific routes to all neighbors. If you want to suppress only advertisements to certain neighbors, you may use the neighbor distribute-list command, with caution. If a more-specific route leaks out, all BGP or multiprotocol BGP routers will prefer that route over the less-specific aggregate you are generating (using longest-match routing).

    Using the suppress-map keyword creates the aggregate route but suppresses advertisement of specified routes. You can use the match clauses of route maps to selectively suppress some more-specific routes of the aggregate and leave others unsuppressed. IP access lists and autonomous system path access lists match clauses are supported.

    Using the advertise-map keyword selects specific routes that will be used to build different components of the aggregate route, such as AS_SET or community. This form of the aggregate-address command is useful when the components of an aggregate are in separate autonomous systems and you want to create an aggregate with AS_SET, and advertise it back to some of the same autonomous systems. You must remember to omit the specific autonomous system numbers from the AS_SET to prevent the aggregate from being dropped by the BGP loop detection mechanism at the receiving router. IP access lists and autonomous system path access lists match clauses are supported.

    Using the attribute-map keyword allows attributes of the aggregate route to be changed. This form of the aggregate-address command is useful when one of the routes forming the AS_SET is configured with an attribute such as the community no-export attribute, which would prevent the aggregate route from being exported. An attribute map route map can be created to change the aggregate attributes.

  3. Gursharn
    October 21st, 2012 at 14:28 | #3

    can anybody please tell me that where can I find the latest dumps for bgp+mpls (Cisco 642-691) exam?

  4. Dinesh Kumar
    December 7th, 2012 at 02:11 | #4

    in CCNA there is tutorial available for each topic before taking the questions and answers. but here it was not available if its available better for us to recalling… Since CCNA explanation given was very simple to learn by anyone.. same expecting for each topic in CCNP as well as CCI………..

  5. CERT
    November 8th, 2016 at 19:49 | #5


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