To BGP or not to BGP...
System and network designers and administrators responsible for the availabiity, performance and cost-effectiveness of their organization's Internet access. Familiarity with basic network terminology and concepts is assumed, however experience with BGP is not required.
Connectivity to the Internet is now a critical communications requirement for many organizations. Adding a second ISP connection can dramatically improve the availability of Internet access, but that improvement is dependent upon correct implementation and determining what constitutes correct can be a daunting challenge.
There are many alternative ways to provide redundant ISP connectivity and just as many conflicting requirements driving that selection. Making the correct choice requires making tradeoffs, and those tradeoffs require not only an understanding of what your requirements are, but also an understanding of the available alternatives and their strengths and weaknesses.
This tutorial starts with a brief overview of some of the diverse requirements which drive Internet connectivity, ranging from simple web acccess to e-commerce providers, highlighting the unique demands that each makes on Internet connectivity. We then explore a wide range of solutions. For each, we discuss how it works and which demands are optimally supported, which are merely satisfied and which fall by the wayside.
Along the way, we will
explore many different ways the Border Gateway Protocol (BGP) can be adapted
and used to meet unique organizational and communications requirements. We will
also explore techniques for getting the advantages of BGP routing to the Internet
without the overhead and cost associated with learning 80,000+ Internet routes.
Among the tradeoffs explored are: * Multiple connections versus multiple sites,
* Single ISP versus multiple ISPs, is it worth the extra cost?
* Static routes versus BGP routing, when is there a choice?
* Default route, indicator routes, and local routes, how much is enough?
* Running defaultless, when is more better and when is it not?
* Load sharing versus backup routes, what is reasonable?
The goal is to help you understand how your current design works and what alternatives exist to let you move closer to an optimal solution for meeting your requirements in your environment.
|Vincent C. Jones, is the founder and principal consultant of Networking Unlimited, Inc., a network design consulting firm specializing in network performance and reliability enhancement. Vince has been applying the theory of networking to the solution of real world problems for almost three decades and is the author of the Addison-Wesley book High Availability Networking with Cisco.|