Something about Router.

RIB, FIB

https://support.huawei.com/enterprise/fr/doc/EDOC1000178171/94a400ab/routing-table-and-fib-table

Host to Host through a Router

https://www.practicalnetworking.net/series/packet-traveling/host-to-host-through-a-router/

https://www.jannet.hk/address-resolution-protocol-arp-zh-hant/