если не активная, то что должно произойти?
При BGP что любая, это вызовет перерасчет хешей коннектов на маршрутизаторе
Using BGP as a load-balancing mechanism has the advantage that you can use standard router hardware, rather than bespoke load-balancers. However, this comes with downsides as well. The biggest is that BGP-based load balancing does not react gracefully to changes in the backend set for an address. What this means is that when a cluster node goes down, you should expect all active connections to your service to be broken (users will see “Connection reset by peer”). BGP-based routers implement stateless load-balancing. They assign a given packet to a specific next hop by hashing some fields in the packet header, and using that hash as an index into the array of available backends. The problem is that the hashes used in routers are usually not stable, so whenever the size of the backend set changes (for example when a node’s BGP session goes down), existing connections will be rehashed effectively randomly, which means that the majority of existing connections will end up suddenly being forwarded to a different backend, one that has no knowledge of the connection in question. The consequence of this is that any time the IP→Node mapping changes for your service, you should expect to see a one-time hit where most active connections to the service break. There’s no ongoing packet loss or blackholing, just a one-time clean break.
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