JUNOS High Availability

Chapter 13. Managing an Interdomain Routing Table

Chapter 12 focused on mechanisms available to control the information that routers and host systems in the local network add to the local routing table. Emphasis was on keeping the table as small as possible through intelligent address allocation, aggregation schemes, and effective use of Interior Gateway Protocol (IGP) scalability tools.

This chapter looks at the current global routing table, which comprises about 230,000 aggregated routes, as a potential addition to the local table. In this chapter, we look at what we can do to control and organize this massive number of potential route additions to the local table. Clearly, the local administrator lacks the authority to control all routes that are added to the global routing table, so measures must be taken on the devices you do control to make sure external factors do not negatively impact internal stability. Controlling how the local Autonomous System (AS) handles the Internet routing table is a fundamental high availability priority for all networks.

When addressing route table content, we must strive for route table stability. Stability has direct implications for high availability, because an unstable routing table results in an unstable network.

With attention to high availability through strong redundancy schemes, this chapter discusses address mechanisms to control ingestion and advertisement of interdomain destinations. These methods include configuration of both confederated ...