Understanding How Nonstop Active Routing Preserves Routing Protocol Information During A Routing Engine Switchover; Nonstop Active Routing Concepts - Juniper EX9200 Features Manual

CHAPTER 7
Understanding How Nonstop Active
Routing Preserves Routing Protocol
Information During a Routing Engine
Switchover

Nonstop Active Routing Concepts

Copyright © 2017, Juniper Networks, Inc.
Nonstop Active Routing Concepts on page 35
Nonstop active routing (NSR) uses the same infrastructure as graceful Routing Engine
switchover (GRES) to preserve interface and kernel information. However, NSR also
saves routing protocol information by running the routing protocol process (rpd) on the
backup Routing Engine. By saving this additional information, NSR is self-contained and
does not rely on helper routers (or switches) to assist the routing platform in restoring
routing protocol information. NSR is advantageous in networks in which neighbor routers
(or switches) do not support graceful restart protocol extensions. As a result of this
enhanced functionality, NSR is a natural replacement for graceful restart.
Starting with Junos OS Release 15.1R1, if you have NSR configured, it is never valid to issue
the command in any form on the NSR master Routing Engine. Doing so
restart routing
results in a loss of protocol adjacencies and neighbors and a drop in traffic.
NOTE: To use NSR, you must first enable GRES on your routing (or switching)
platform. For more information about GRES, see
Routing Engine Switchover" on page
NOTE: Starting with Junos OS Release 12.3, due to its synchronization
requirements and logic, NSR/GRES performance is limited by the slowest
Routing Engine in the system.
"Understanding Graceful
3.
35