What is the purpose of the weight attribute in an EID-to-RLOC mapping?

Question

Options

• AIt determines the administrative distance of LISP generated routes in the RIB.
• BIt indicates the load-balancing ratio between ETRs of the same priority.
• CIt indicates the preference for using LISP over native IP connectivity.
• DIt identifies the preferred RLOC address family.

• A
  6% (1)
• B
  88% (14)
• C
  6% (1)

Explanation

LISP EID-to-RLOC Mapping: Weight Attribute

In LISP (Locator/ID Separation Protocol), the weight attribute defines how traffic is distributed across multiple RLOCs (Routing Locators) that share the same priority value, essentially controlling the load-balancing ratio - for example, a weight of 75 on one ETR and 25 on another means 75% of traffic goes to the first. This makes Option B correct.

Why the distractors are wrong:

• Option A is incorrect because administrative distance is a routing protocol concept applied in the RIB; LISP uses priority and weight within its own mapping system, not AD values.
• Option C is incorrect because preference between LISP and native IP connectivity is governed by the priority attribute (lower priority = preferred), not weight.
• Option D is incorrect because RLOC address family (IPv4 vs. IPv6) is identified by the RLOC address itself, not a weight value.

Memory Tip: Think of weight like a weighted scale - it only matters when two RLOCs are equal competitors (same priority), and the heavier side gets more traffic. "Same Priority → Weight decides the split" (P before W, just like the alphabet).

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