I'm about to change ISP's. I connect to our current ISP #1 with a static route pointing my default route (0.0.0.0) to his dsl modem.
I will route to my new ISP #2 using BGP. I expect he will hand me a default route ( 0.0.0.0 ), and I assume the new BGP route will be of a lower priority than the static ? ( i.e. the static will be selected first ) Given this I have instructed ISP #1 to prepend the route that he advertises for us so that when we advertise to ISP #2 this new route will be higher priority than ISP #2. No dramas so far.
However, when I start advertising my route to ISP #2 via BGP, these routes will eventually filter to the internet and assume a higher priority than the prepended route of ISP #1.
My question is, what effect will my static route to ISP #1 have on the traffic that comes from ISP #2, particularly as it returns back to the source IP ? I see a situation whereby the route will filter to some sources who will com in via ISP #2 and then on returning to the source will pick up the static from ISP #1 and return via that link ?
Cheers - and thanks in advance