Installation guide

Functional Description
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Cisco IOS 11.2(15)GS2
Choosing the correct primary GRP is important. If only one of the two GRPs has a valid startup-config, that
GRP becomes the primary. If a GRP with an invalid startup-config became primary, that invalid configuration
could be copied to the other GRP, destroying the correct version. Avoiding an invalid startup-config is why the
arbitration mechanism evaluates whether a GRP has a startup-config that was saved while in this router chassis,
and whether the startup-config is the most recent one saved in the chassis.
You can override most of the arbitration mechanism and specify that the GRP in a particular slot is
the primary whenever the system boots. See the command description for the redundancy prefer
EXEC command for usage guidelines.
Secondary Console
The console port on the secondary GRP appears directly connected to a vty port on the primary GRP.
This allows either console to be used to monitor and control the router. However, if there is a permanent failure
on one GRP, you can use the console connected directly to the other GRP. This is why you have separate
connections to the console ports of both GRPs.
Device Access
When the GSR is running in redundant mode, the primary GRP can access the secondary GRP
NVRAM and Flash.
Most users will want to keep the startup-config file on the secondary GRP identical to the
startup-config file on the primary GRP. Automatic synchronization is enabled by default and can be
configured by using the auto-sync main-CPU redundancy configuration command. In auto-sync
mode, changes to the primary startup-config file are automatically applied to the secondary.
No equivalent synchronization mechanism exists for the Flash devices. The Flash devices must be
synchronized manually if you want to keep the Flash on the secondary GRP identical to the Flash in
on the primary GRP.
When using file management commands such as copy and delete, you can specify the command
affects the secondary GRP by adding “sec-” to the device name. For example,
copy slot0: sec-slot0:
Device names that accept sec- are as follows:
sec-slot0:
sec-slot1:
sec-bootflash:
sec-nvram:
Whenever you update the startup-config file on the secondary GRP, that action updates the ROM
monitor variables and the configuration register on the secondary GRP.
These settings may not be exact copies of the primary's ROM monitor variables and configuration register.
Instead, the variables and settings are set to appropriate values, as determined by the primary GRP, which may
differ from those on the primary due to specific hw-module global configuration commands. The end result is
that any ROM and configuration register settings
on the secondary GRP are overwritten by the values
chosen by the primary GRP.