The reason for that is because IP is not 'integrated' with layer-2 tech like Ethernet. In fact, for a very long time Ethernet was only really used on local networks. Point-to-Point Protocol (PPP) [1] is a completely separate data link layer technology with no real concept of MAC addresses, because there can only be two devices on the bus.
Most of the very expensive 'multilayer' switches [2] do a form of this where they associate a next-hop IP with a MAC address entry and store that in the TCAM or data layer. It's not used as much because Cisco has a ton of patents on this type of technology, and also because general purpose hardware has gotten quick enough that it's not as important as it was ~15 years ago...
Most of the very expensive 'multilayer' switches [2] do a form of this where they associate a next-hop IP with a MAC address entry and store that in the TCAM or data layer. It's not used as much because Cisco has a ton of patents on this type of technology, and also because general purpose hardware has gotten quick enough that it's not as important as it was ~15 years ago...
[1] https://en.wikipedia.org/wiki/Point-to-Point_Protocol
[2] https://en.wikipedia.org/wiki/Multilayer_switch#Layer-3_swit...