{"id":698,"date":"2026-07-14T10:08:34","date_gmt":"2026-07-14T10:08:34","guid":{"rendered":"https:\/\/ip4.market\/blog\/698-2\/"},"modified":"2026-07-14T10:08:36","modified_gmt":"2026-07-14T10:08:36","slug":"loa-and-ipv4-leasing-guide","status":"publish","type":"post","link":"https:\/\/ip4.market\/blog\/loa-and-ipv4-leasing-guide\/","title":{"rendered":"LOA and IPv4 Leasing Guide"},"content":{"rendered":"
\nIn this article:<\/strong><\/p>\n
    \n
  1. What is a Letter of Authorization (LOA)?<\/a><\/li>\n
  2. The Mechanics of BGP Announcement for Leased Space<\/a><\/li>\n
  3. The Role of RIRs and the WHOIS Database<\/a><\/li>\n
  4. Leasing vs. Ownership: Administrative Differences<\/a><\/li>\n
  5. Best Practices for Network Engineers<\/a><\/li>\n<\/ol>\n<\/div>\n

    Scaling infrastructure without the brutal capital expenditure of buying IPv4 blocks? Leasing looks like the obvious exit. But then you hit the wall. Getting an LOA for IPv4 leasing<\/strong> right trips up even engineers who have been BGP peering for years. It\u2019s not just paperwork. If you don’t execute this authorization correctly, your upstream ISPs will simply drop your routes. The space won’t be globally routable. It\u2019s a dead end.<\/p>\n

    What is a Letter of Authorization (LOA)?<\/h2>\n

    Think of an LOA as a signed permission slip. The owner of the block grants you\u2014a third party\u2014the right to use and announce that specific space. In the messy reality of IPv4 leasing, this document is the only bridge of trust between the resource holder, the entity using the IPs, and the upstream ISPs carrying the traffic.<\/p>\n

    Here is the friction. When you lease, the Regional Internet Registry (RIR) records still show the original owner. They are the maintainer. Your upstream provider cannot just look up the database to verify you. They need an LOA to prove the current holder actually sanctioned you to announce their prefixes.<\/p>\n

    \nKey Tip:<\/strong> Always ensure the LOA is on the official letterhead of the registered resource holder and includes the signature of an authorized contact. Without this, ISPs will likely reject your BGP request.\n<\/div>\n

    The Mechanics of BGP Announcement for Leased Space<\/h2>\n

    Announcing leased IP space isn’t just a router configuration. It is a coordination dance between the Lessor, you (the Lessee), and the Upstream Providers. Miss a step, and the session stays down.<\/p>\n

      \n
    1. Secure the Lease Agreement:<\/strong> Get the contract locked down for the specific IPv4 block (a \/24, perhaps).<\/li>\n
    2. Obtain the LOA:<\/strong> The lessor must provide a signed LOA. It needs to specify the exact prefixes and the ASNs allowed to announce them.<\/li>\n
    3. Submit to Upstream:<\/strong> You send the LOA to your ISP or transit provider. They use this to validate the request in their portal.<\/li>\n
    4. Create ROA (optional but recommended):<\/strong> If the lessor agrees, have them create a Route Origin Authorization (ROA) for your ASN in RPKI. It prevents route hijacking.<\/li>\n
    5. Configuration:<\/strong> Configure your edge routers to advertise the prefix. And watch your no-export<\/strong> communities if the agreement limits propagation.<\/li>\n<\/ol>\n

      Why LOAs Matter for Route Security<\/h3>\n

      Try announcing without a valid LOA. The ISP sees a hijack attempt or a leak. Given the stricter filtering we’ve seen since incidents like the Facebook outage in 2021, documentation is your first line of defense. Providers are risk-averse. They want auditable proof that the announcement is sanctioned by the legitimate resource holder. No paper, no route.<\/p>\n

      The Role of RIRs and the WHOIS Database<\/h2>\n

      This is where confusion usually sets in with LOA for IPv4 leasing<\/strong>. People look at the WHOIS database and get stuck. In a typical lease, legal ownership does not change hands. ARIN, RIPE NCC, APNIC, or LACNIC will continue to list the Lessor as the organization maintaining the block.<\/p>\n

      I\u2019ve seen engineers assume they need to update the maintainer details immediately. Not necessarily. While some contracts allow for “Maintainer Object” transfers\u2014where the Lessee becomes the technical contact\u2014most leases skip that administrative overhead. Instead, the LOA acts as an override mechanism. You manage the routing policy. They keep the registration rights.<\/p>\n

      Leasing vs. Ownership: Administrative Differences<\/h2>\n

      Buying IPv4 space outright gives you a “Transfer” receipt from the RIR. You become the legal registrant. You control the ROAs, the POC records, the routing policy. Leasing is different. You rely on the Lessor for specific actions.<\/p>\n

      \n\n\n\n\n\n\n\n\n
      Feature<\/th>\nIPv4 Ownership<\/th>\nIPv4 Leasing (with LOA)<\/th>\n<\/tr>\n<\/thead>\n
      RIR Record<\/strong><\/td>\nUpdated to Buyer (End-user)<\/td>\nStays with Lessor<\/td>\n<\/tr>\n
      ROA Creation<\/strong><\/td>\nDone directly by Owner<\/td>\nRequires Lessor cooperation<\/td>\n<\/tr>\n
      Upstream Verification<\/strong><\/td>\nWHOIS\/RPKI check<\/td>\nLOA + WHOIS check<\/td>\n<\/tr>\n
      Capital Cost<\/strong><\/td>\nHigh (Asset purchase)<\/td>\nLow (Operational expense)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
      \nWarning:<\/strong> If you lease IP space, ensure your SLA with the Lessor guarantees a specific turnaround time for issuing new LOAs or updating ROAs. If their contact goes dark, you could lose your ability to announce the prefixes.\n<\/div>\n

      Best Practices for Network Engineers<\/h2>\n

      Want this to go smoothly? Stick to the protocols that experienced engineers use:<\/p>\n