subnet.im

157.21.128.0/17

Old Dominion UniversityAS1201

At a glance

Addresses

32,768

/17 block

Visibility

30%

23 of 77 vantage points

RPKI

No ROA

Registry

ARINUS

Allocated 12th December 1991

AS paths to this prefix

One real path per vantage point, fanning out from the origin. Where two reach the prefix the same way, those hops are drawn once. Open a path to follow it hop by hop.

OriginVantage points
AS path graph: 5 observed paths to 157.21.128.0/17, fanning out from AS1201 toward the vantage points that see it. Each path is written out in full beneath the graph.AS1201Old Dominion Univ…OriginAS40220Virginia Polytech…AS35280F5 Networks SARLAS6939Hurricane Electri…AS8529Zain Omantel Inte…AS20130Depaul UniversityAS24482SG.GSAS38623Metfone (Viettel …AS23673Cogetel Online, C…AS137409GSL Networks Pty …AS49127Asimo Networks B.…AS8283Netwerkvereniging…AS8298IPng Networks GmbH
  1. Sao Paulo12014022035280This path
  2. London, UK12014022069398529This path
  3. Oregon, US120140220693920130This path
  4. Singapore120140220244823862323673This path
  5. Amsterdam1201402201374094912782838298This path

Each row is one path genuinely present in the routing table at our last snapshot, read outward from the origin to the vantage point that saw it. Open a row to follow that one path hop by hop. A heavier line in the graph means more vantage points reach the prefix that same way.

Route visibility

30%

Seen by 23 of 77 full-feed vantage points

Seen by few vantage points

Observed at 5 of our collectors.

What this percentage counts

The denominator counts only full-feed peers — peers carrying a substantially complete routing table at the moment of the snapshot. IXP route-server peers usually feed partial tables and are excluded, because including them would make a normally propagated prefix look as though half the internet could not see it.

It measures how widely an announcement has spread across the networks we can observe. It says nothing about whether the prefix is reachable from any particular place, or how it performs.

Registry and RPKI

RIR
ARIN — North America
Country
United States
Allocated
12th December 1991
Allocation block
157.21.0.0/16
Status
allocated
Origin validation
No ROA

No ROA covers this prefix, so RPKI has nothing to say about it either way. This is still the common case for a large share of the routing table.

Prefix hierarchy

Announcements above, below and beside this one in the real routing table.

CoveringMore specific
Prefix hierarchy for 157.21.128.0/17: the announcements covering it on the left, the announcements inside it on the right. Every prefix drawn is also listed in the tables below.157.21.0.0/16AS1201157.21.128.0/17AS1201This prefix157.21.0.0/17AS1201157.21.128.0/18AS1201157.21.192.0/18AS1201

Left to right is specificity: a shorter mask covering more address space, then this prefix, then the announcements carved out inside it. Only the first few of each are drawn — the tables below list them all.

Covering announcements

Announcements that contain 157.21.128.0/17
PrefixAddressesOriginVisibility
157.21.0.0/1665.5kAS1201Old Dominion University76/77

More specific announcements

Announcements contained within 157.21.128.0/17
PrefixAddressesOriginVisibility
157.21.128.0/1816.4kAS1201Old Dominion University35/77
157.21.192.0/1816.4kAS1201Old Dominion University35/77

Sibling prefixes

Prefixes of the same length sharing a parent block with 157.21.128.0/17
PrefixAddressesOriginVisibility
157.21.0.0/1732.8kAS1201Old Dominion University23/77

History

  1. AS120122nd September 2026 — present
Why these dates start where they do

A first-seen date is the first time we saw that origin, not the first time it appeared in BGP. Our history is forward-only with no backfill, so it says nothing about the period before we started collecting — treat the earliest dates with suspicion.

Open 157.21.128.0/17 in the calculator/17 reference

Routing data derived from RouteViews MRT archives and public registry data.