about the the src/dst MAC address you have probably read in everywhere how encapsulation and decapsulation of a frame works. On a per hope basis the MAC address is stripped off and replaced with a new one having the next hop mac address as dst MAC and the outbound interface as SRC MAC. About the IP, you are missing to provide a lot of info. For example, there is NAT in the middle? Is there MPLS? R1 is connected to R2 via what:
- GRE or what else?
To describe a purely IPv4 path is not that difficult and possibly you know it mucch better than many here, but we are talking about a not-defined CLOUD in between two ASA that could even maskerade the IP!!
Too many things can happen between ASA1 and ASA2
Provide a more specific question and it will be easier to answer. I am not an expert as you can see