AS11452 MOUNT-SINAI

MOUNT-SINAI belongs to the Mount Sinai School of Medicine in New York City — the academic medical school now known as the Icahn School of Medicine at Mount Sinai, and the research and teaching arm of the Mount Sinai health system. It announces 14 IPv4 prefixes totalling roughly 55,000 addresses, with five observed BGP neighbours.

What it's used for

This is an academic medical centre's campus network. Nearly the whole inventory is one contiguous legacy block, 146.203/16, sliced into three /18s plus a set of longer, more specific announcements (/21, /22, /24) carved out of the same space. Deaggregating your own /16 like that is the signature of a single institution engineering its own traffic — steering particular subnets toward particular upstreams, or holding a more-specific to keep a route from being hijacked. It is not the shape of a network stitched together from acquired odds and ends.

Notable

Every prefix the pack resolved registers to MSSMEDU-1, org Mount Sinai School of Medicine. The holder announces its own registered space, which settles the question of whether the AS number and the address space have drifted apart. The five neighbours are consistent with a large institution buying redundant transit, not with a carrier: a wholesale network at this address count would show neighbours in the hundreds.

Interesting

A tens-of-thousands-of-addresses IPv4 footprint with no IPv6 announced at all is common in this cohort. The /16 was large enough that address pressure never forced the issue.