Why not keep it simple?
Why networks use routing protocols, BGP and redundant links instead of a few static routes, when they shouldn't, and what the extra complexity buys. With a real experiment: one quiet link failure, three designs, measured.
By the end you will be able to:
- Explain the three forces that push a network beyond static routing: failure, growth and other networks
- Describe why a backup link with static routes often fails to protect against quiet failures
- Decide when a default route, an IGP or BGP is the simplest design that works
- Name the guard rails that make powerful routing protocols safe to operate
Most of what this site teaches looks, at first glance, like complication for its own sake: routing protocols instead of a few static routes, two links where one would do, loopbacks, route reflectors, communities, firewalls in zones. If you've ever thought "why not just keep it simple?", this lesson is for you, and the honest answer starts with: you're partly right.
Simplicity is a real virtue in networks. Every extra protocol is something to configure, monitor, understand at 3 a.m. and get wrong. A small office with one internet connection should have a default route and nothing more. Running BGP there would add risk and buy nothing.
So the useful question isn't "simple or complicated?". It's "what does this extra piece buy, and is that worth what it costs?" Three forces push networks beyond the simplest design, and every technique in these lessons answers at least one of them:
- Things fail. Links, routers, power, providers, and the people configuring them. A network that has to keep working through failures needs more than one path, and a way to choose between paths without a human.
- Networks change and grow. Every new site, subnet or link has to be known by every router that needs it. By hand, that work grows faster than the network does.
- You don't control the other networks. The internet is tens of thousands of independent organisations. None of them will configure your routes for you; they can only tell you what they can reach.
When none of these applies, static routing is the right answer. The rest of this lesson is about what happens when they do, starting with an experiment.
Check your understanding
A small office has one internet connection and one router. A consultant proposes running BGP with the ISP. What's the best response?
- Decline: with one provider, a default route does everything BGP would, with less to go wrong.
- Accept: BGP is the professional choice for any internet connection.
- Accept, but only with BFD.
- Use OSPF with the ISP instead.