Hi, The issue, like many others, comes from the trust-based nature of the great internets. Just because well-meaning networks have no reason to fake self-report as Anycast, in the absence of a mechanism to actually validate that, some less well-meaning networks could make the marking useless. The communities are not only used for TE, so routing hot/cold/mashed potatoes is just one way to use that info, among others. Then, the good and fake information becomes useless bits moved around with BGP, globally, or until some transit strips them. I can imagine a bunch of people conducting "research" using something like [1] to create an imaginary "Tier 1" on the Facebook-of-the-Internet or other sites by marking all routes as Customer or Internal. [1] https://datatracker.ietf.org/doc/html/draft-ymbk-grow-bgp-collector-communit... Radu On 11/25/2025 6:44 PM, Gert Doering wrote:
Why would they do that?
The idea about "tagging as anycast" is not to make other networks prioritize these (and prioritize in which way, anyhow?) but to give them the chance to do informed decisions on hot/cold-potato routing, which might look different for anycast and for non-anycast prefixes - or, when faced with "what looks like funny routing", to do better informing debugging.
Gert Doering -- NetMaster