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Cisco IOS XR Getting Started Guide
OL-10957-02
Chapter1 Introduction to Cisco IOS XR Software
Selecting and Identifying the Designated Shelf Controller
•Selecting and Identifying the DSC on Cisco CRS-1 Routers, page 1 -8
•Selecting and Identifying the DSC on Cisco CRS-1 Multishelf Systems, page 1-8
•Selecting and Identifying the DSC on Cisco XR 12000 and 12000 Series Routers, page 1-9
Selecting and Identifying the DSC on Cisco CRS-1 Routers
A Cisco CRS-1 router supports up to two RPs. If only one RP is installed, that RP automatically becomes
the DSC. If two RPs are installed, the default configuration selects RP0 as the DSC. To select RP1 to
become the DSC for a new installation, install RP1 first, apply power to the system, and wait for RP1 to
start up. When the Primary LED on the RP1 front panel lights, RP1 is operating as the DSC, and you can
install RP0.
Tip After the router starts for the first time, you can use the redundancy reddrv command to select which
RP becomes the DSC during a restart.
The active RP and DSC lights the Primary LED on the RP front panel. The alphanumeric LED display
on the active RP displays ACTV RP. By default, the other RP becomes the standby RP, displays STBY
RP on the alphanumeric display, and takes over if the DSC fails.
To visually determine which RP is operating as the DSC in a Cisco CRS-1 router, look for the RP on
which the Primary LED is lit. You can also look for the RP that displays the ACTV RP message on the
alphanumeric display.
Selecting and Identifying the DSC on Cisco CRS-1 Multishelf Systems
A Cisco CRS-1 Multishelf System supports up to two RPs in each LCC. Each LCC must have at least
one RP, so a multishelf system supports between two and four RPs. The RPs in a multishelf system
operate much like the RPs in a standalone router. The difference is that only one LCC can host the DSC.
During the initial startup of a multishelf system, the DSC is RP0 in the LCC with the lowest configured
rack number, which is usually Rack 0. If you want to select RP1 within Rack 0 to become the DSC,
install RP1 first, and wait for RP1 to start up. When the Primary LED on the RP1 front panel l ights (or
the alphanumeric display shows ACTV RP), RP1 is operating as the DSC, and you can install RP0. If
you are setting up a new multishelf system, the instructions in Cha pter 3, “Bringing Up the Cisco IOS
XR Software on a Multishelf System,” specify the appropriate time to bring up and configure the DSC.
Tip After the router starts for the first time, you can use the redundancy reddrv command to select which
Rack 0 RP becomes the DSC during a restart.
The active RP and DSC lights the Primary LED on the RP front panel. The alphanumeric LED display
on the active RP displays ACTV RP. By default, the other RP becomes the standby RP, displays STBY
RP on the alphanumeric display, and takes over if the DSC fails.
After the DSC starts up in Rack 0, the DSC remains in Rack 0 while at least one RP in Rack 0 is operating
properly. If both RPs in Rack 0 fail, the active RP in the other rack becomes the DSC. The process of
moving the DSC function from one rack to another is called DSC migration. For more information on
DSC migration, see the Cisco IOS XR System Management Configuration Guide, Release 3.4.