Configuring Secure Domain Routers on Cisco IOS XR Software
Information About Configuring Secure Domain Routers
SMC-137
Cisco IOS XR System Management Configuration Guide
another 30 seconds. This causes an inconsistent system view in the named SDR using DRP paired across
the rack in which the DRP loses control Ethernet connectivity, but the LR plane is still working and can
bring the named SDR into an inconsistent view if the named SDR is across the rack.
To support DSC migration in Cisco IOS XR Software Release 3.3.2 and higher, we recommend that you:
•Keep the default placement of all four RPs in the owner SDR. When the owner SDR spans both
LCCs, the impact on the SDR resources is minimal in the remaining rack. Existing connections are
not interrupted for the resources in the remaining rack, but a delay in routing new connections can
occur while the routing tables are updated.
•Run all routing protocols in a named SDR. In addition, by running all routing protocols in a named
SDR, which requires a distributed route processor (DRP) paired across the rack, the operation of
Cisco Nonstop Forwarding (NSF) and Cisco Nonstop Routing (NSR) continues.
An election process selects the node that is to receive the DSC role upon DSC migration. The basis of
the election is the shelf number. The shelf with the lowest number is designated to receive the DSC role.
DSC migration can cause a very short interruption to traffic flowing through the owner SDR. Although
the time can vary with the addition of new features to DSC management and other factors, in the current
release the time is likely to be around 20 to 30 seconds.
The reason for the traffic loss is because virtual Interfaces (VI), such as loopback, null, tunnels, and
bundles are hosted on the DSDRSC of an SDR. For the owner SDR, the DSDRSC is the same node as
the DSC itself. For DSC migration to occur, both active and standby DSC must be lost. Therefore, for
the owner SDR, both active and standby DSDRSC are lost. VI's must be recreated on the new DSC,
which is also the new DSDRSC. This operation takes some time, during which routing protocols such
as BGP that use loopback or null interfaces are affected. Similarly, tunnels and bundles must also be
recreated, affecting protocols such as MPLS. As a result, there is a drop in traffic in the default or owner
SDR.
Note In Cisco IOS XR Software Release 3.3.0 and higher, DSC migration is disabled if the RPs in both LCCs
are assigned to different SDRs.
To minimize the impact of DSC migration, create named SDRs that operate on DRP in each LCC. If the
DSC rack fails, any named SDRs on the failed rack also fail. However, named SDRs on the unaffected
rack can continue through DSC migration without any interruption in service. If the failure in the DSC
rack affects only the RP cards, the named SDR in the affected rack cannot function after the RPs on that
rack go down.
Cisco IOS XR Software Package Management
Software packages are added to the DSC of the system from Administration Exec mode. Once added, a
package can be activated for all SDRs in the system, or for a specific SDR.
Note In Release 3.3.0, SDR-specific activation is supported for specific packages and upgrades, such as
optional packages and SMUs. Packages that do not support SDR-specific activation can only be activated
for all SDRs in the system. For detailed instructions, see the “Managing Cisco IOS XR Software
Packages” module of the Cisco IOS XR Getting Started Guide. See also the “Software Package
Management Commands on Cisco IOS XR Software” module of the Cisco IOS XR System Management
Command Reference.