| Prefix | Block | Addresses | Country | First registered |
|---|---|---|---|---|
| 00:23:8A | MA-L | 16.8 million | US | 8 Oct 2008 |
| 04:79:FD | MA-L | 16.8 million | US | 8 Nov 2023 |
| 14:4E:2A | MA-L | 16.8 million | US | 4 Oct 2018 |
| 18:92:A4 | MA-L | 16.8 million | US | 21 Sep 2019 |
| 1C:11:61 | MA-L | 16.8 million | US | 5 Oct 2017 |
| 20:80:58 | MA-L | 16.8 million | US | 19 Jun 2019 |
| 24:65:E1 | MA-L | 16.8 million | US | 9 Jan 2025 |
| 2C:39:C1 | MA-L | 16.8 million | US | 14 Jan 2014 |
| 2C:4A:11 | MA-L | 16.8 million | US | 7 Oct 2020 |
| 54:C3:3E | MA-L | 16.8 million | US | 31 May 2018 |
| 5C:07:A4 | MA-L | 16.8 million | US | 8 Nov 2023 |
| 74:87:BB | MA-L | 16.8 million | US | 15 Mar 2018 |
| 78:5F:A4 | MA-L | 16.8 million | US | 8 Oct 2025 |
| 78:D7:1A | MA-L | 16.8 million | US | 10 Jul 2020 |
| 84:8D:CE | MA-L | 16.8 million | US | 16 Jun 2022 |
| 90:DF:06 | MA-L | 16.8 million | US | 11 Feb 2026 |
| 94:43:4D | MA-L | 16.8 million | US | 29 Feb 2020 |
| 98:11:CC | MA-L | 16.8 million | US | 8 Oct 2025 |
| 9C:7A:03 | MA-L | 16.8 million | US | 18 Jun 2015 |
| AC:89:D2 | MA-L | 16.8 million | US | 13 Dec 2022 |
| C4:83:6F | MA-L | 16.8 million | US | 14 Oct 2016 |
| C8:CA:79 | MA-L | 16.8 million | US | 18 Aug 2021 |
| D0:19:6A | MA-L | 16.8 million | US | 14 Feb 2019 |
| D4:39:B8 | MA-L | 16.8 million | US | 14 Oct 2020 |
| D4:B7:D0 | MA-L | 16.8 million | US | 5 Aug 2021 |
| D4:E4:C3 | MA-L | 16.8 million | US | 17 Dec 2024 |
| E0:9B:27 | MA-L | 16.8 million | US | 13 Dec 2022 |
| E4:6D:7F | MA-L | 16.8 million | US | 16 Jun 2022 |
| E4:FE:E4 | MA-L | 16.8 million | US | 11 Feb 2026 |
| EC:B0:E1 | MA-L | 16.8 million | US | 8 Aug 2017 |
Every block registered to Ciena Corporation in the IEEE registries, complete. Free-text search also matches former owners.