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 MX routers have inherited the complete suite of field-proven Junos HA features, which, when combined with sound network design principals, enable HA.
This chapter starts with a brief overview of the HA features available on all MX routers; subsequent sections will detail the operation, configuration, and usage of these features.
Graceful Routing Engine Switchover (GRES) is the foundation upon which most other Junos HA features are stacked. The feature is only supported on platforms that have support for dual REs. ...