Hi
from my understaning now you will have two DCs active and standbay and they are interconnected towgather for example or you have an idnetical Public IP range to be advertised to two diffrent ISPs then to the interent
in this case i would recomend you to obtain your own Public BGP ASN then use this AS number in both DC/DR and advertise the same range of public IPs
from the DR you can use AS path Prepending to adverise this range with longer AS path to make it less prefered, once the DC is down this route from the DR will be used to reach your public range thorugh the DR
however there are some points you need to check
- someISP they use internal polices that effect BGP attributes useing BGP community strings and this you need to obtain it from the ISP
- you need to let the ISPs to permit your Public BGP ASN and the IP range you have ot be addvertised as some of then they block it unless allocted by them
note: you may be able to use two diffrent BGP ASN in DC and DR but it is not as good as if you have it one BGP AS more controled as some ISP might give it preference to thier local customers over the other AS !!!
HTH
if helpful Rate
