You’ve learned the ins and outs of integrating SRX into your organization’s own routed networks, but what if you need to connect an SRX to the global Internet? This section gives you the tools to do just that.
Although there’s a plethora of choices for gluing together your internal routed networks (OSPF, IS-IS, RIP), there is just one protocol for the global Internet: Border Gateway Protocol (BGP).
BGP has been central to the functioning of the global Internet for two decades. It was created in the time when “the Internet” was just a handful of educational and research institutions connected together via the government-funded National Science Foundation Network (NSFNET). BGP has survived, to its creators’ great surprise, through to the enormous and privately funded global spider web of service providers and corporations that is called “the Internet” today.
BGP is very different from the interior gateway protocols such as OSPF, IS-IS, and RIP that you reviewed earlier. It is the sole surviving exterior gateway protocol (EGP) in use today. It is designed specifically for router peering between organizations. Where IGP protocols assume some level of trust and freely pass their routing information between routers once adjacencies are formed, an EGP protocol can never take trust for granted. This is why the routing policy covered in the preceding section is so fundamental to building any real-world BGP configuration.
BGP must cope with a much larger routing world. Whereas ...