Workshop

There’s one special static route you’ll want to know about called the default route. This is represented by
the destination network 0.0.0.0 and is the route used when a packet has a destination that isn’t covered
by anything else in the routing table.
Routing protocols are based on the concept that each router “knows” which network it lives on, and that
it can communicate which networks it knows about to other routers. Looking at Figure 14.3 again, it
makes sense that Router 1 could tell Router 2 about the 192.168.1 network, and that Router 2 could
tell Router 1 about the 192.168.3 network—along with the 192.168.4 network, once Router 3 told
Router 2 about it. Whoa. It’s a good thing this happens more or less automatically, because in a large
network, writing this out could get really hairy. Again, here’s how dynamic routes would work in this
sample network:
Router 1 Tells Router 2 about 192.168.1
Router 2 Tells Router 1 about 192.168.3
Tells Router 3 about 192.168.1
Tells Router 1 about 192.168.4
Router 3 Tells Router 2 about 192.168.4
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