Chapter 10. Junos High Availability on MX Routers

This chapter covers Junos software high-availability (HA) features supported on MX routers. These HA features serve to lessen, if not negate, the impacts of software or Routing Engine (RE) faults that would otherwise disrupt network operators and potential impact revenue.

The topics discussed in this chapter include:

  • Junos HA feature overview

  • Graceful Routing Engine Switchover

  • Graceful restart

  • Nonstop routing and nonstop bridging

  • In-service software upgrades

  • ISSU demonstration

Junos High-Availability Feature Overview

Numerous HA features have been added to Junos software in the 13 years since its first commercial release. These enhancements were in keeping with the ever more critical role that networks play in the infrastructure of modern society. As competition increased in the networking industry, both Enterprise and Service Providers demanded HA features so that they, in turn, could offer premium services that included network reliability as a critical component of their Service Level Agreements (SLAs).

Gone are the days of hit-and-miss network availability, whether caused by failing hardware or faulty software; people just can’t get their jobs done without computers, and for most people, a computer these days is only as useful as its network connection. This is the era of “five nines” reliability and achieving that goal on a yearly basis can be demanding. When luck is simply not enough, it’s good to know that ...

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