Configuring BGP Routing Policy for AS 2000

D.

Sure, I'd be happy to provide a detailed explanation of this question.

This question is asking you to configure a BGP routing policy for AS 2000 that satisfies several requirements based on RFC1998. Let's break down the requirements and look at each answer choice to see which one meets all of them.

1. Modify the local-preference value for prefixes containing BGP community values 2000.90 and 2000:110 Answer choices A, B, and C all include a clause that modifies the local-preference value for these prefixes. Answer choice D also modifies the local-preference value, but it does so after deleting a BGP community, which is not required by the question.

2. Strip any BGP community of the BGP prefixes received from customers that are in the range between 2000:1 and 2000:2000 Answer choices A and C both include a clause that deletes any BGP community in this range. Answer choice B also deletes communities, but it does so in a way that is not correct for the question (using a "in" clause instead of a "matches-any" clause). Answer choice D does not include a clause to delete communities in this range.

3. Any other BGP community values must not be removed Answer choices A, B, and C all use the "delete community all" clause to ensure that no other communities are removed. Answer choice D deletes specific communities, so it does not meet this requirement.

4. Apply 2000:1003 BGP community value, which indicates that the BGP prefix is learned from a customer All answer choices include a clause to set the 2000:1003 community value.

Based on these requirements, answer choice A is the correct configuration for the BGP routing policy. It includes all the necessary clauses to satisfy the requirements, and does not include any extra clauses that are not needed. Answer choices B and C also meet most of the requirements, but have minor errors that make them incorrect (using "in" instead of "matches-any" in answer B, and adding the "additive" keyword in answer C which is not required by the question). Answer choice D is incorrect because it deletes specific communities instead of using the "delete community all" clause to avoid removing any other communities.

Therefore, the correct answer is A:

sqlCopy code
route-policy CUSTOMER-COMMUNITIES    if community matches-any (2000:90) then      set local-preference 90    elseif community matches-any (2000:110) then      set local-preference 110    endif    if community matches-any (2000:[1..89], 2000:[91..109], 2000:[111..2000]) then      delete community all    endif    set community (2000:1003)  end-policy