I'm trying to piece together the algorithm in 6833-bis S 5.5 for Map-Replies. The text says:
A Map-Reply returns an EID-Prefix with a mask-length that is less than or equal to the EID being requested. So, consider the case where an MS has two mappings: 10/8 -> ETR1 11/8 -> ETR2 If the Map-Request is for 10.0.0.1, then I would return 10/8 -> ETR1 Now consider what happens when I have three mappings: 10/16 -> ETR1 10.0.2/24 -> ETR3 // New 11/16 -> ETR2 Now we turn to the remainder of this section: When an EID moves out of a LISP site [I-D.ietf-lisp-eid-mobility], the database mapping system may have overlapping EID-prefixes. Or when a LISP site is configured with multiple sets of ETRs that support different EID-prefix mask-lengths, the database mapping system may have overlapping EID-prefixes. When overlapping EID- prefixes exist, a Map-Request with an EID that best matches any EID- Prefix MUST be returned in a single Map-Reply message. For instance, if an ETR had database mapping entries for EID-Prefixes: I'm having trouble parsing this, but what I get out of the example is that the Map-Response is supposed to contain the EID-prefix that best matches the request, plus whatever exceptions would be required to create a correct routing table. So, that would mean in the case where the Map-Request contains 10.0.0.1, the MS would have to reply with: 10/16 -> ETR1 10.0.2/24 -> ETR3 // New The first of these is necessary to provide correct routing information for the requested prefix and the second to avoid providing incorrect routing information for 10.0.2.1. Do I have this correct? It seems like the alternative is that the MS or ETR synthesize a new, more specific prefix. Is that what's intended instead? The example in S 5.5 suggests otehrwise, but perhaps I am misunderstanding. Thanks, -Ekr
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