Have Internet from two providers. For example, one buy multiple IP addresses. How to make it so that disabling one service provider to a home server to be accessible from the network of another provider for the same IP?
UPD! As implemented in data Centers?
No way. How do you imagine that? Only the other IP. To do this, configure the load balancer and DNS to the 3rd party.
Technology called anycast. Using it can be done even automatically to your clients chose a better channel of communication, even when 2 providers available at the same time. However, the simultaneous use of two providerof there pitfalls from exploding TCP sessions, but when used simultaneously, only one provider is no such problem, except switching between them.
For her self-introduction you'll need to buy a block of 256 addresses and register themselves AS (for AS and need 256 addresses, for a smaller unit AS not give). It is now 30 000 rubles per year for addresses like. Plus how many there are still sponsorship LIRŅ (I don't think you want to become a LIR).
In this case, in the presence of AS - you sea .... um.. on the knee. Do not have to ask permission from providers (perhaps if they filter out other people's IP, just to warn them to not do it, but it's easier than following the agreement).
For combining use of anycast without existing AS (whether you bought the address) - will have to negotiate with the provider to allow the BGP announcements of IP addresses not belonging to this provider.
And, not sure, maybe Yes, maybe no: but whether this provider else to agree about these things with my own providername in turn, or enough announcements took only your direct provider.
under the same IP in any way. if dropped, then dropped.
you need either an external balancer or configure the DNS TTL to 10 minutes to be able to fly to change A record.
approximately:
in DC there are 1 IP and a few pieces of iron that are configured in occasionally mode (if you die one of the glands, or drop service will not fall)
but if you fall Sam dash, at least be 100 irons - IP issued by Prov will not be available, and the glands will not be available
does
in the DTS is realized through the BGP Protocol, but to buy a sub-mesh is not cheap, podate to her link via the home provider is not real,and throw a commercial link is very expensive.