High-Availability Capability for Applying an SMU

B.

In Cisco ASR 9000 devices, an SMU (Software Maintenance Upgrade) is a software package that includes bug fixes, security patches, and other software enhancements. Applying an SMU on a production device can cause downtime, which can lead to service interruptions for end-users. Therefore, it's essential to minimize the impact of applying an SMU to ensure high availability of services.

There are several high-availability capabilities that can minimize the impact of applying an SMU on a Cisco ASR 9000 device, as listed in the question. Let's take a closer look at each of them:

A. Install activate: Install activate is a feature that allows a user to install a new software package on a Cisco ASR 9000 device without disrupting the existing services. The new software package is installed on a separate disk partition, and the device continues to run on the existing software package. Once the installation is complete, the user can activate the new software package, which causes the device to reboot and switch to the new software package. The install activate feature can reduce downtime and service interruptions during software upgrades.

B. ISSU (In-Service Software Upgrade): ISSU is a feature that allows a user to upgrade the software on a Cisco ASR 9000 device without disrupting the existing services. With ISSU, the new software package is installed on a standby RP (Route Processor), which runs in parallel with the active RP. Once the installation is complete, the user can switch the device to the standby RP, which becomes the active RP, while the previous active RP becomes the standby RP. The device continues to run on the new software package, without any service interruptions. ISSU can provide continuous service during software upgrades.

C. Graceful Restart: Graceful Restart is a feature that allows a device to continue forwarding traffic while it's rebooting. When a device reboots, it sends a message to its neighboring devices, informing them that it's about to restart. The neighboring devices continue to send traffic to the restarting device, which buffers the traffic until it completes the reboot process. Once the device is back online, it sends another message to its neighbors, informing them that it's ready to receive traffic. The neighbors can then start sending traffic to the device again. Graceful Restart can minimize the impact of rebooting on network traffic.

D. NSF (Non-Stop Forwarding): NSF is a feature that allows a device to continue forwarding traffic during a software upgrade. With NSF, the device sends a message to its neighboring devices, informing them that it's about to upgrade its software. The neighboring devices continue to send traffic to the upgrading device, which forwards the traffic based on its existing forwarding table. Once the software upgrade is complete, the device sends another message to its neighbors, informing them that it's ready to receive traffic. The neighbors can then send updated forwarding information to the device, which updates its forwarding table. NSF can provide continuous forwarding during software upgrades.

E. NSR (Non-Stop Routing): NSR is a feature that allows a device to continue routing traffic during a software upgrade. With NSR, the device sends a message to its neighboring devices, informing them that it's about to upgrade its software. The neighboring devices continue to send routing updates to the upgrading device, which updates its routing table based on the existing routing information. Once the software upgrade is complete, the device sends another message to its neighbors, informing them that it's ready to receive routing updates. The neighbors can then send updated routing information to the device, which updates its routing table. NSR can provide continuous routing during software upgrades.

In the context of the question, the high-availability capability that can minimize the impact of applying an SMU on a Cisco ASR 9000 device is ISSU