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Hey everyone,

I'm trying to get a clearer understanding of how TCP/IP packets are routed across different networks. Specifically, I'm interested in the role of routers, IP addresses, subnet masks, and routing tables in this process. What are the key steps a packet takes from source to destination when traversing multiple hops?

Any insights or diagrams would be greatly appreciated!

Thanks in advance!

Hi JohnDoe,

Great question! Routing is a fundamental concept. Here's a breakdown of the process:

1. Packet Creation: When you send data, it's broken down into packets. Each packet contains a header with source and destination IP addresses, along with other control information.
2. Local Network Decision: If the destination IP is on the same local network (determined by the subnet mask), the packet is sent directly to the destination MAC address using ARP.
3. Router Involvement: If the destination is on a different network, the packet is sent to the default gateway (a router).
4. Router's Role: The router examines the destination IP address in the packet's header.
5. Routing Table Lookup: The router consults its routing table, which is a database of network routes. It looks for the best match for the destination IP.
6. Forwarding Decision: Based on the routing table, the router forwards the packet to the next hop (another router or the destination network).
7. Repeat: This process repeats at each router along the path until the packet reaches its destination network.

The subnet mask is crucial for identifying if an IP address belongs to the local network or a remote one. Routing tables are dynamically updated via routing protocols (like OSPF, BGP) or statically configured.

Thanks, AlicePortia! That explanation is very helpful. I'm a bit confused about the difference between static and dynamic routing tables. When would you prefer one over the other?