Letter of Authorization (LOA)
A letter of authorization (LOA) is a document that authorizes Cloudflare to announce a prefix(es) on behalf of another entity. Some backbone and transit providers require that Cloudflare provide them with an LOA whenever Cloudflare starts to announce a customer prefix.
The letter must contain both the prefixes you are authorizing Cloudflare to announce, and which ASN they will be announced under. Cloudflare can announce a prefix under your ASN or you are welcome to use ours. If you want Cloudflare to use our ASN, just let us know and we will provide the AS number to put in the LOA document.
An LOA is a formal document which should be on company letterhead and contain a wet signature. Feel free to use the example template.