How to Use Unified ISSU with Enhanced Mode
Unified ISSU with Enhanced Mode Overview
Enhanced mode is an in-service software upgrade (ISSU)
option available on MPC8E, and MPC9E line cards that eliminates packet
loss during the unified ISSU process. This is achieved by taking advantage
of new line card architecture improvements that make it possible to
have a second copy of the Junos OS software running on the line card
in standby mode ready to take over while software moves from an old
image to a new one during unified ISSU. You can enable enhanced mode
by adding the enhanced-mode option to the request
system software in-service-upgrade CLI command.
SUMMARY Use this document to learn about unified ISSU with enhanced mode and how to use it.
Benefits of Unified ISSU with Enhanced Mode
Unified ISSU with enhanced mode provides the following benefits:
Upgrades to a new software version with no loss of transit or host bound traffic
Reduces packet loss to zero or several milliseconds depending on configuration and network conditions
Allows software upgrades to be performed without the need for maintenance windows
Uses the existing unified ISSU process and doesn’t require any special configuration
Prerequisites for Performing Unified ISSU with Enhanced Mode
Before you begin a unified ISSU with enhanced mode, there are several prerequisites to keep in mind:
The device running unified ISSU with enhanced mode must use an MPC8E, or MPC9E line card.
Note:If you are performing unified ISSU with enhanced mode on a device that has a mix of supported and unsupported line cards, there will be sub-second traffic loss for traffic passing through the unsupported line cards.
Note:If you are performing unified ISSU with enhanced mode on guest network functions (GNFs), then all GNFs should be using MPC8E, or MPC9E line cards to avoid traffic loss.
The Linux version running on your Flexible PIC Concentrator (FPC) and the line card Linux version in the target release need to be compatible.
Enhanced mode won’t work if the target release carries changes that require the ASIC blocks to be reset.
Forwarding memory usage should be below 75 percent to ensure no packet loss during the unified ISSU process
Note:Unified ISSU with enhanced mode will still work if forwarding memory usage is above 75 percent, but it might introduce several milliseconds of packet loss.
All prerequisites for unified ISSU also apply to enhanced mode. See Unified ISSU System Requirements for more information.
You can check to see if your device can use unified ISSU with
enhanced mode to upgrade to a specific release by using the request
system software validate in-service-upgrade package-name.tgz enhanced-mode command. If your device and the target release
are not compatible with enhanced mode, you can still use regular unified
ISSU to upgrade with minimal disruption of traffic.
Performing Unified ISSU with Enhanced Mode
To perform a unified ISSU with enhanced mode, follow these steps:
Download the software package by following the procedure in Downloading Software.
Copy the software package or packages to the device. We recommend that you copy the file to the
/var/tmpdirectory.Log in to the console connection. Using a console connection allows you to monitor the progress of the upgrade.
Verify that you can use unified ISSU with enhanced mode for your desired release.
On the device, enter:
user@host>
request system software validate in-service-upgrade /var/tmp/package-name.tgz enhanced-modewhere
package-name.tgzis the name of the software package you downloaded in Step 1.
Start the unified ISSU with enhanced mode:
On the device, enter:
user@host>
request system software in-service-upgrade /var/tmp/package-name.tgz enhanced-moderebootwhere
package-name.tgzis the name of the software package you downloaded in Step 1.
Note:During the upgrade, you will not be able to access the Junos OS CLI.
The device displays status messages similar to the following messages as the upgrade executes:
Chassis ISSU enhanced-mode ISSU: set chassis enhanced-mode Chassis ISSU Check Done ISSU: Validating Image .. mgd: commit complete Validation succeeded Validating Image Done Preparing Backup RE Pushing /var/tmp/junos-install-mx-x86-32-20.1.tgz to re1:/var/tmp/junos-install-mx-x86-32-20.1.tgz Pushing package /var/tmp/junos-install-mx-x86-32-20.1.tgz to re1 done Installing package /var/tmp/junos-install-mx-x86-32-20.1.tgz on re1 … Verified sflow-mx signed by PackageDevelopmentEc_2019 method ECDSA256+SHA256 NOTICE: 'pending' set will be activated at next reboot... ISSU: Installing package /var/tmp/junos-install-mx-x86-32-20.1.tgz on re1 done ISSU: Rebooting Backup RE Rebooting re1 Backup RE Prepare Done Waiting for Backup RE reboot Backup RE reboot done. Backup RE is up Waiting for Backup RE state synchronization Backup RE state synchronization done GRES operational "Initiating Chassis In-Service-Upgrade" Chassis ISSU Started ISSU: Preparing Daemons ISSU: Daemons Ready for ISSU ISSU: Offline Incompatible FRUs ISSU: Starting Upgrade for FRUs … ISSU: Preparing for Switchover ISSU: Ready for Switchover Checking In-Service-Upgrade status Item Status Reason FPC 1 Online (ISSU) FPC 2 Offline Configured power off Resolving mastership... Complete. The other routing engine becomes the master.
Note:If the unified ISSU process stops, you can look at the CLI output by using the
request system software in-service-upgradecommand to diagnose the problem. You can also look at syslog files for more information.Log in after the reboot of the device is completed. To verify that the software has been upgraded, enter the following command:
user@host>
show version
When using unified ISSU with enhanced mode, the base Linux OS on your FPC cannot be upgraded as part of the ISSU process. Linux can be updated with an upgrade done through regular unified ISSU or a reboot of the FPC.