This article is intended to provide step-by-step instructions on how to complete NSSU software upgrade on a virtual chassis of EX4600, EX4650, QFX5100 and QFX5120 Juniper Networks switching platforms.

Customer needs instructions on how to perform NSSU (Nonstop Software Upgrade) software upgrade on a virtual chassis of EX4600, EX4650, QFX5100 and QFX5120 Juniper Networks switching platforms. Nonstop software upgrade (NSSU) enables you to upgrade the software running on a switch or Virtual Chassis with redundant Routing Engines using a single command and with minimal disruption to network traffic.

Before proceed with NSSU upgrade on your virtual chassis, you must verify that the SDK version of the currently running Junos version is the same as the SDK version of the target Junos version. Please consult with Juniper TAC team to confirm this.

Once the SDK versions are confirmed to be the same, we can continue with NSSU process as per detailed below.
 

1) Download the Junos OS image: Obtain the target Junos OS software image from the Juniper support website Juniper Downloads.

2) Copy the Junos OS image to a /var/tmp location of the master routing engine.

3) Always make sure that the checksum matches the one that is listed in Juniper downloads. You may use the command below. Note that if the checksum does not match, chances are that the integrity of the package may have been corrupted during file transfer. If all FTP/SCP attempts cause this issue, you should transfer the file by USB as per detailed in KB [Junos] How to mount a USB drive on EX/SRX/MX/QFX Series platforms to import/export files

user@switch> file checksum md5 /var/tmp/jinstall-host-ex-4e-x86-64-21.4R3-S5.17-secure-signed.tgz

4) Ensure that the virtual chassis is Preprovisioned. Note that Non-preprovisioned VC configuration is not compatible with NSSU upgrade feature. Below is an example of Preprovisioned VC configuration. It is also important to remark that the "no-split-detection" stanza is recommended on 2-member VC stacks. For VC stacks with more than two members, you do not need it.

user@switch# set virtual-chassis no-split-detection
user@switch# set virtual-chassis preprovisioned
user@switch# set virtual-chassis member 0 role routing-engine
user@switch# set virtual-chassis member 0 serial-number ABCDSERIAL
user@switch# set virtual-chassis member 1 role routing-engine
user@switch# set virtual-chassis member 1 serial-number FGHISERIAL

5) You must enable Graceful Routing Engine switchover (GRES) and nonstop active routing (NSR) features along with commit synchronize as it is needed for a successful commit. Below are the commands to configure these features.

user@switch# set chassis redundancy graceful-switchover
user@switch# set routing-options nonstop-routing
user@switch# set system commit synchronize

6) Proceed with NSSU upgrade with the command below. Note that it is suggested to have console access available in case something goes wrong during the process, and keep in mind that there might be minimal service disruption even if successful.

user@switch> request system software nonstop-upgrade /var/tmp/jinstall-host-ex-4e-x86-64-21.4R3-S5.17-secure-signed.tgz no-validate force-host.

Note: The NSSU feature is not a zero-downtime guarantee, the Feature Explorer indicates that it is intended for minimal disruption of network traffic. For comparison, regular software upgrade process implies several minutes of downtime as it causes the virtual chassis members to reboot, and the network traffic is disrupted throughout the entire reboot time.

Note: NSSU is also applicable for Mixed Virtual Chassis.

2024-04-18 : Article Created

2024-12-14: Adding note about Mixed VC