I work for a company who provides internet services to hotels. We recently have a new client. They have two ISP connections, one for hotel guests and another for hotel admin network. Currently these two links are independent and separate. They ask me if it's possible to make both redundent to each other, so normally, traffic sourced from admin network will be sent out from ISP1 link and traffic sourced from guest side will use ISP2 link. And when one link is down, all traffic go on another link.
They also want public IP on the admin gateway (which is an ASA) and don't want any NAT in the process.
So here is my thought:
Let's say the router has 4 interfaces. First two are for connection to two ISPs and let's say their IP ranges are A and B. Guest side gateway will be on network C and admin ASA will be on network D and they will be connected on the rest two ports of the router.
I think in this case, both ISP1 and ISP2 have to aware of both network C and D, correct? Then in case one link is down, another link can pickup and still route for both C and D. We also want, in normal case, traffic destinated to admin ASA will always use link1/A and traffic destinated to guest side gateway will always use link2/B. Is that something ISP can easily done? Will that cost a lot? I will for sure check with ISP but just want to have a basic idea how much it will cost.
I also googled and I see solution of using BGP. I think they mean run the BGP on the 1841 router and tell the both ISPs that it has network C and D directly connected. However will I be able to configure BGP to tell both ISPs that when both links are up, always use link1 for admin ASA traffic and link2 for guest side traffic? If possible, can anybody please paste a sample config? Is this using BGP ease configuration for the ISP and save cost?
Hotel also asks if 1841 is good enough for it because they have a spare one. What do you think?
Any suggestions are welcome! If my solution is not a good one, let me know if there is a better alternative. Thank you!