AS11501 VISTAASN

VISTAASN belongs to Vista Radiology, P.C., a physician-owned radiology practice based in Knoxville, Tennessee. It is a single-enterprise network: the practice runs its own AS purely to carry its own clinical traffic, not to sell anything to anyone.

What it's used for

Corporate connectivity for a medical group. Vista Radiology reads imaging for hospitals and imaging centres across East Tennessee, with a main office on Laurel Avenue in Knoxville and partnering sites scattered through the region, so its network exists to move studies between those sites and its radiologists. That is the workload behind the AS: PACS and teleradiology traffic, plus the ordinary back office.

Notable

The routing is about as small and self-contained as a real AS gets. RIS sees 3 IPv4 prefixes and 512 addresses, and the prefix list explains that immediately: a 198.205.6.0/23 plus its two constituent /24s. That is one /23 announced at two granularities, so the practice's entire routed footprint is 512 addresses. No IPv6 is announced at all.

Only 2 observed BGP neighbours. A network that peers with two ASes is buying transit from a small number of providers and selling none, which is exactly what you would expect of a clinical practice that runs BGP for dual-homed redundancy rather than for any network business. All three prefixes are registered to Vista Radiology's own ARIN org, so holder and space agree with no third parties in between.

Interesting

Announcing both the /23 and its halves is a common trick for a dual-homed site: the covering route keeps the block reachable while the more-specifics let each /24 prefer a different upstream. For a practice whose uptime requirement is "the radiologist can open the scan", that redundancy is the whole point of running an AS at this size.