Route Processor Redundancy; Stateful Switchover - Cisco ASR1000-RP1 - ASR 1000 Series Route Processor 1 Router Software Configuration Manual

Chapter 5 High Availability Overview

Route Processor Redundancy

Route Processor Redundancy (RPR) allows you to configure a standby RP. When you configure RPR,
the standby RP loads the Cisco IOS software on bootup and initializes itself in standby mode. In the
event of a fatal error on the active RP, the system switches to the standby RP, which reinitializes itself
as the active RP. In this event, the entire system is rebooted, so the switchover with RPR is slower than
with other High Availability switchover features such as Nonstop Forwarding/Stateful
Switchover (NSF/SSO).
On the Cisco ASR 1000 Series Router, RPR can also be used to enable a second IOS process on a single
RP for a Cisco ASR 1002 or 1004 Router. See the
Router" section on page 5-4
For the Cisco ASR 1000 Series Routers, RPR introduces the following functionality:
•
•
It is important to note that in most cases, Stateful Switchover (SSO) requires less downtime for
switchover and upgrades than RPR. RPR should only be used when there is a compelling reason to not
use SSO.
It is important to note RPR is supported on the Cisco ASR 1000 Series Routers while RPR+ is not.

Stateful Switchover

The Stateful Switchover (SSO) feature takes advantage of processor redundancy by establishing one of
the processors as the active processor while the other RP is designated as the standby processor, and then
synchronizing critical state information between them. Following an initial synchronization between the
two processors, SSO dynamically maintains RP state information between the dual processors.
Stateful Switchover is particularly useful in conjunction with Nonstop Forwarding. SSO allows the dual
processors to maintain state at all times, and Nonstop Forwarding lets a switchover happen seamlessly
when a switchover occurs.
On the Cisco ASR 1000 Series Router, SSO can also be used to enable a second IOS process on a single
RP for a Cisco ASR 1002 or 1004 Router. See the
Router" section on page 5-4
It is important to note that in most cases, SSO requires less downtime for switchover and upgrades than
RPR. RPR should only be used when there is a compelling reason to not use SSO.
For additional information on NSF/SSO, see the
OL-16506-10
for additional information on the second IOS process.
Startup configuration synchronization between the active and standby RP or IOS process. It is
important to note, however, that changes in the running configuration are not synchronized using
RPR.
Warm Reload—The Warm Reload feature allows users to reload their routers without reading
images from storage; that is, the router reboots by restoring the read-write data from a previously
saved copy in the RAM and by starting execution without either copying the software from flash to
RAM or self-decompression of the image.
for additional information on the second IOS process.
Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide
"Second IOS Process on a Cisco ASR 1002 or 1004
"Second IOS Process on a Cisco ASR 1002 or 1004
Cisco Nonstop Forwarding
Route Processor Redundancy
document.
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