Earlier quoted context omitted.
I totally understand why Comcast, AT&T, Verizon and other service providers would want /16s. They are continent wide providers with millions of customs (millions of sites). I'm trying to grok why MIT went for a /24 instead of a /32. Because they could?
Because they are replacing their /8. They want to make sure they are never constrained.
If they had requested a boring /48 IPv6 allocation (that anybody can have just by asking) - they would have had 2^16 /64 networks, and each network could have had basically an infinite number of hosts.
But, this is the IPv6 world, so I would have expected MIT to claim they were a LIR (Local Internet Registry - equivalent of a small ISP or larger) - and asked for a /32 - which would have given them 2^32 networks - or 4 Billion networks to work with. They probably would have assigned the networks by segmenting them on a per site basis - so each site would have had a /48 assigned, so they could have up to 65K sites, each site having 65K networks, each network having (effectively) infinite number of hosts. That is, a /32 would have been far, far, far larger than their /8 was. Easier to manage as well (no VLSM - nothing ever smaller than a /64) And, keep in mind, with a single, no contest request, they could have gotten the /32 adjacent to theirs (another 4 Billion networks, or 65K /48s) so they could aggregate on a /31.
Instead, they've asked for a /24. And I'm just darn intrigued as to why they think they can make use of such an address space. If they weren't constrained with their /8, then a /32 would have been far more than they ever required. (And odds are a /48 would have been sufficient with even modest address management).
I mean, I work with really large mesh networks, millions of nodes, some of our subnets have 20K nodes each on them - we roll out /48s like they are nothing, and even after deploying a couple hundred customers over 10 years, and 25 million nodes, I think we've used up maybe 1500 /48s.
BTW - this doesn't even take into account that they can use RFC 4193 up the wazoo for all sorts of interesting non-globally routable experimental internal networks.
I"m just hoping someone from MIT is reading HN and will clue us in.