Architecture Design Trade-offs

Most new networking designs have trade-offs; they offer new features and improvements but bring with them their own unique costs and caveats. It is little wonder then that agreement cannot be reached on how best to evolve the architecture of the Internet. The research paper on NIRA, a new inter-domain routing architecture, is one example of an Internet proposal upgrade. The proposal is elegant, relies on existing ideas and deployments like IPv6 as much as possible, and offers feature that could be useful for society. Specifically, the protocol aims to give users the ability to choose between available routes between a source and destination. As a side effect, it will also exhibit improved scalability relative to the existing inter-domain routing protocol BGP.

Of course, NIRA is not without potential flaws. First, it allocates IPv6 addresses in a specific way so as to limit other potential uses for the same address space. Second, it's protocol for communicating topology changes and user up-graphs has a per-message overhead linear with the number of domain-level links in a user's up-graph. Third, the network state a user must maintain is theoretically exponential in the depth of a user's up-graph. And last of all, if NRLS updates, analogous to DNS updates, are frequent they could also result in scalability issues as the Internet grows.

On one hand, the authors argue effectively that all of the above potential issues are unlikely to be realized in practice. On the other hand, the protocols of the original Internet also met their most important design goals, but at the same time have been stretched in ways their original authors never imagined. Is NIRA's added value important enough to integrate in the next Internet? Would its design weaknesses eventually become serious problems? As with the current Internet architecture, only time will tell!