What are two characteristics of L3VPNs? (Choose two.)
A.
Matching route targets are required for L3VPNs to function correctly.
B.
Multiprotocol BGP is required for L3VPNs to function correctly.
C.
The IPv4 NLRI is required for L3 VPNs to function correctly.
D.
Matching route distinguishers are required for L3VPNs to function correctly.
Explanation:
D: When customer networks that use private addresses connect to the Internet infrastructure, the private
addresses might overlap with the same private addresses used by other network users. MPLS/BGP VPNs
solve this problem by adding a route distinguisher.
A: The PE router uses the route target to constrain the import of remote routes into its VRF tables.
Incorrect Answers:
B: Multiprotocol BGP is not required for L3VPNs.
Note: Multiprotocol Extensions for BGP (MBGP), sometimes referred to as Multiprotocol BGP or Multicast BGP
and defined in IETF RFC 4760, is an extension to Border Gateway Protocol (BGP) that allows different types of
addresses (known as address families) to be distributed in parallel.
In Junos OS, Layer 3 VPNs are based on RFC 4364. RFC 4364 VPNs are also known as BGP/MPLS VPNs
because BGP is used to distribute VPN routing information across the provider’s backbone, and MPLS is used
to forward VPN traffic across the backbone to remote VPN sites.
http://www.juniper.net/documentation/en_US/junos15.1/topics/concept/layer-3-vpn-overview.html
the correct answer should be A and B.
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I totally agree with You
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I agree with A, B
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The following components must be added to the PE switches for an MPLS-based Layer 3 VPN:
– BGP group with family inet-vpn unicast
– Routing instance with instance type vrf
Note: Each routing instance that you configure on a PE switch must have a unique route distinguisher associated with it. VPN routing instances require a route distinguisher to allow BGP to distinguish between potentially identical network layer reachability information (NLRI) messages received from different VPNs. If you configure different VPN routing instances with the same route distinguisher, the commit fails.
https://www.juniper.net/documentation/en_US/junos/topics/example/mpls-qfx-series-vpn-layer3.html
Every VRF table has one or more extended community attributes associated with it that identify the route as belonging to a specific collection of routers. One of these, the route target attribute, identifies a collection of sites (VRF tables) to which a PE router distributes routes. The PE router uses the route target to constrain the import of remote routes into its VRF tables.
https://www.juniper.net/documentation/en_US/junos/topics/concept/layer-3-vpn-overview.html
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https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_l3_vpns/configuration/15-mt/mp-l3-vpns-15-mt-book/mp-bgp-mpls-vpn.pdf
For me A and B
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Ans : A & B
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A & B.
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This is an awful question. How can answer D possibly be right? Juniper even recommend using the PEs’ Router ID as the Route-Distinguisher. This means, by definition, the local PEs RD and remote PEs RD will be different!
Surely A&B are the right answers!
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Options A & B is the best answers, however A, B and D are good answers.
Each routing instance that you configure on a PE router must have a unique route distinguisher associated with it. VPN routing instances need a route distinguisher to help BGP to distinguish between potentially identical network layer reachability information (NLRI) messages received from different VPNs.
Option C is not actually needed if you configure the inet-vpn address family and unicast traffic type, those will enable BGP to carry IPv4 NLRI for VPN routes.
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