Question

I just finished a phone interview. The interviewer asked me a question:

Tell me about what happen about IP
packet go through router.

It’s been long time since I study networking. And I just say something about router transmission list and there are several router protocols such as OSPF etc. . that’s it.
Could anybody give a good answer to this? or lead me check some resources?
Thank you!!

Answer 1

A router is a network layer device. So, when it receives an IP packet, the IP packet current destination is set to that router. So, router does this:

1. Checks the packet’s final destination.
2. From its routing table, it finds the the next hop router to reach that destination
3. Adds that next hop router’s address to that packet, sends it over to its link layer (which adds the frame header and trailer)
4. Then, that packet is off to that next hop router.

This way, that packet sails off to its final destination

PS: I had taken a Computer Networking course last quarter