I would like to know what exactly happens to a packet once it reaches an interface, through which exact steps does it go and the precise order. Both inbound and outbound traffic. Something like a flow chart.. I can't find a proper document that shows this.
Appreciate any help in advance.
Your question is very generic. The way packet processed varies depending on if it routed switched, what all services are configured on the router. Also it depends on the platform
Can you specify if it is a CEF router, or harware swiched platfrom and the kind of traffic
General packet forwarding steps:
1. Layer 2 engine performs the input VLAN ACL lookup
2. If necessary, an input router ACL check is performed
3. The destination IP addr. is compared against Layer 3 FIB.
4. The Layer 2 and Layer 3 header rewritten (according Adjacency table)
5. Layer 2 forwarding engine forwards the frame.
Link about packet switching methods: