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Re: [RRG] Consensus check: mapping granularity



On 3/20/08 7:23 AM, Robin Whittle allegedly wrote:
I don't understand what the problem is with having one, many, or
most EID prefixes (LISP) or micronets (Ivip) being a single IPv4
address.

One of the major benefits of ALT (actually, the only one, I think)
is that it can have endless divisions of the address space, without
burdening the ITRs, since they only cache whatever mapping they need
at the time.  So there's no scaling problem due to the number of
EIDs in terms of the ITRs or the conceptual nature of the ALT system
- you just add more ETRs and/or more storage capacity in these ETRs.

The problem is in fact on the sender side, the ITR side. The receiver side, and LAT aren't problems, but smaller mapping granularity can cause problems for the encapsulator's cache strategy. You need to think about how many individual endpoints a typical medium organization connects to, and figure out how much memory it would need. What about Google, which needs to communicate with most endpoints in the world, and often? Cache generally doesn't work in a situation like that. They would have to aggregate into prefixes themselves, and carefully manage which ITR send to which prefix.

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