Dual Router Path: Multi-Hop Routing

The scenario

PC-Left (10.0.1.10) and PC-Right (10.0.3.10) are on different networks with two routers between them. Router-A joins 10.0.1.0/24 to the transit network 10.0.2.0/24; Router-B joins 10.0.2.0/24 to 10.0.3.0/24. OSPF is switched off on both routers, so each one knows only the networks plugged into it plus the static routes typed into it: Router-A has 10.0.3.0/24 via 10.0.2.2 (Router-B), and Router-B has 10.0.1.0/24 via 10.0.2.1 (Router-A). Neither router sees the whole path. Each only decides where the packet goes next, and the reply is routed the same way in the other direction.

What you will work out

Understand how a packet crosses several routers, each making its own next-hop decision, and why the reply needs routes of its own.

Why this matters

Every path across more than one router depends on each router having a route onward and a route back. When a request shows up at the far end but the sender sees a timeout, or a traceroute stops partway, the cause is usually one router's table. Small networks and network edges often use static routes like these; larger networks let a routing protocol such as OSPF or BGP install them instead.

Running it

Dual Router Path: Multi-Hop Routing opens on a canvas, already wired and addressed. Trace a packet through it hop by hop, or run the same topology live on real Linux network namespaces. How the two modes differ.