Comprehensive and Detailed In-Depth Explanation:
1. Understanding VPN Route Targets (RTs) in MPLS VPNs
* Route Targets (RTs) define which VPN routes should be imported and exported among PE routers.
* Import-extcommunity: Specifies which VPN routes should be accepted into a VRF.
* Export-extcommunity: Specifies which VPN routes should be advertised from a VRF.
* Correctly configuring RTs ensures proper route exchange between VPN sites.
2. Analyzing the RTs in the Diagram
R3's Current Configuration:
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vpn-target 3:1 export-extcommunity
vpn-target 3:2 export-extcommunity
vpn-target 1:3 export-extcommunity
vpn-target 1:3 import-extcommunity
vpn-target 3:1 import-extcommunity
vpn-target 3:2 import-extcommunity
R1's Configuration:
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vpn-target 1:3 export-extcommunity
vpn-target 3:1 import-extcommunity
R2's Configuration:
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vpn-target 2:3 export-extcommunity
vpn-target 3:2 import-extcommunity
* R3 has redundant RTs because it both exports and imports unnecessary RTs.
* We need to remove only redundant RTs without affecting NMS connectivity.
3. Evaluating Each Answer Choice
A: "undo vpn-target 3:1 import-extcommunity" (# Incorrect)
* R1 exports RT 1:3, and R3 imports it as 3:1.
* Removing 3:1 import-extcommunity would block R3 from receiving routes from R1, disrupting connectivity to NMS.
* Thus, this option is incorrect.
B: "undo vpn-target 1:3 export-extcommunity" (# Correct)
* R3 exports RT 1:3, but there is no need for R3 to advertise routes with 1:3.
* R1 already exports 1:3, and R3 only needs to import it.
* Removing vpn-target 1:3 export-extcommunity does not affect connectivity but eliminates redundancy.
* # This is a correct choice.
C: "undo vpn-target 1:3 import-extcommunity" (# Incorrect)
* R3 needs to import 1:3 to receive routes from R1 (which is required for NMS communication).
* If removed, R3 will not receive necessary routes, breaking connectivity.
* Thus, this option is incorrect.
D: "undo vpn-target 2:3 export-extcommunity" (# Correct)
* R2 exports RT 2:3, but R3 does not need to receive it.
* This RT is redundant and can be removed without affecting connectivity.
* # This is a correct choice.
4. Evaluating the Answer Choices
Option
Correct?
Reasoning
A
# Incorrect
R3 must import 3:1 from R1 to maintain connectivity.
B
# Correct
Removing export-extcommunity 1:3 eliminates redundancy without affecting connectivity.
C
# Incorrect
Removing import-extcommunity 1:3 would block R3 from receiving necessary routes.
D
# Correct
Removing export-extcommunity 2:3 eliminates redundancy without affecting connectivity.
# Correct answer: B and D.
Final Conclusion:
* Route Targets (RTs) are used in MPLS VPNs to control route import/export policies.
* R3 has redundant RTs, and removing unnecessary exports (1:3 and 2:3) optimizes configuration.
* Correct commands to remove redundancy without affecting connectivity are:
* # undo vpn-target 1:3 export-extcommunity
* # undo vpn-target 2:3 export-extcommunity
* Thus, the correct answer is: B and D.

Comprehensive and Detailed In-Depth Explanation:
To analyze the correct answer, we need to break down the topology and protocol behaviors step by step:
* Understanding the IS-IS and OSPFv3 Network Setup:
* IS-IS IPv6 is running between R2, R6, and R3.
* OSPFv3 is running on other links.
* Area 1 is a stub area, which means it does not accept external routes but can have a default route (::/0).
* Area 2 is an NSSA (Not-So-Stubby Area), meaning it allows external routes as NSSA external LSAs.
* Analysis of Each Answer Option:
A: "The routing table of R6 contains the route ::/0." # FALSE
* R6 only participates in IS-IS (Level-1) and does not receive a default route (::/0) from Level-
2 routers.
* Since R6 is in IS-IS Level-1 and does not have a connection to a Level-2 router that provides a default route, it will not have a ::/0 route in its routing table.