AS12551 AS-ENEL-

Italy's electricity utility announcing 35 prefixes, nine of which reassemble into a single /19.

What it's used for

• Corporate connectivity for a national electricity company. 72,192 addresses in 35 IPv4 prefixes, five observed BGP neighbours, and no IPv6 announced.

Notable

• Every block carries the same netname, ENEL-NET, registered to ENEL S.p.A with an Enel Energia abuse department as contact.
• Nine of the announcements — 146.133.0.0/23, 2.0/23, 4.0/22, 8.0/21, 16.0/22, 20.0/22, 24.0/22, 28.0/23 and 30.0/23 — cover 146.133.0.0/19 exactly, with nothing left over and nothing overlapping.
• The inventory spans two unrelated ranges, 146.133 and 158.47, cut into everything from a /18 down to /23s.
• Some blocks are registered to an ENEL LIR and others directly to ENEL S.p.A.

Interesting

• Announcing nine prefixes where one /19 would do is the recurring artefact of this range, and it is not a mistake so much as a habit. Each piece was probably turned up separately, for a different site or purpose, and nobody ever went back to collapse them once the whole range was in use.
• Thirty-five prefixes for five neighbours is the opposite of a transit network. A utility's network follows its physical estate — substations, plants, regional offices — and the fragmentation is that estate showing through into BGP.
• ENEL also appears in this range as a customer: AS12533, a small Italian ISP, has a host named enel in its reverse zone. Large utilities show up in the routing table both as themselves and as somebody else's dedicated circuit.