This may well be a stupid question, but imagine this:
I have Router1-ISP1 and Router2-ISP2.
My goal is that all egress traffic should flow thru Router1-ISP1. In case of failure, Router2-ISP2 should be used.
I could influence routes with BGP attributes such as localpreference or weight.
Instead, why not just use HSRP and set Router1-ISP1 as active and Router2-ISP2 standby?
Then the ingress traffic:
If I understand correctly, influencing ingress traffic is not a straighforward process since it depends on agreement with ISP.
So my question is, why use BGP attributes for control of egress traffic if HSRP could be used in this case? What is wrong with my rationale?