Nice lecture, thanks. But I saw always when thinking about multihoming some other problems also. 2] Multihomed to different ISP without BGP, supposing I need only one /24. It will be PA or PI addressing space ?? With respect to CIDR aggregation effort, make it sense to require /24 PI address block?? How will route the second ISP my PA from the other ISP (he will de-aggregate the block of the second provider to announce more specific prefix??) ?? 2] Multihomed to different ISP with BGP , supposing I need only one /24. Again, make it sense to have my own AS and /24 PI block ?? Supposing to have IBGP to one ISP (to avoid assigning of independent AS) and EBGP to the second ISP, again will my router announce the /24 inside of the first ISP address block to the EBGP peer ?? 2. Multi-homed. Enterprise connects to more than one ISP. May or may not use BGP. Wishes to protect against problems in the ISP routing system, and will accept additional complexity and router requirements to get this. May also have differing service agreements for Internet access for different divisions.