Juniper on Denis Nolan

Updating Juniper MX With USB

Wed, 15 Oct 2025 11:56:41 +0100

Sometimes you have a Juniper MX router that may have firmware version from a number of years ago. Juniper usually can update at most 3 versions ahead. So for example you can potentially upgrade a device from Junos 21.3 to 23.3. However should your version be 20.1, you’re advised to upgrade to a version within the 3 max hops.

The alternative is to upgrade straight away using a USB key especially as it is a cleaner install and quicker all round. In my experence that is.

Junos Running on Backup Image

Mon, 26 Sep 2022 21:47:50 +0100

I’ve come across this mostly with SRX units where the device is running on a backup image. This generally happens if the unit suffers a power cut.

Message
#

***********************************************************************
**                                                                   **
**  WARNING: THIS DEVICE HAS BOOTED FROM THE BACKUP JUNOS IMAGE      **
**                                                                   **
**  It is possible that the primary copy of JUNOS failed to boot up  **
**  properly, and so this device has booted from the backup copy.    **
**                                                                   **
**  Please re-install JUNOS to recover the primary copy in case      **
**  it has been corrupted and if auto-snapshot feature is not        **
**  enabled.                                                         **
**                                                                   **
***********************************************************************

Steps
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show system alarms

1 alarms currently active
Alarm time               Class  Description
2022-03-07 09:05:08 GMT  Minor  Host 0 Boot from backup root

show chassis alarms

1 alarms currently active
Alarm time               Class  Description
2022-03-07 09:05:08 GMT  Minor  Host 0 Boot from backup root

show system storage partitions

Boot Media: internal (da0)
Active Partition: da0s1a
Backup Partition: da0s2a
Currently booted from: backup (da0s2a)

Partitions information:
  Partition  Size   Mountpoint
  s1a        2.4G   altroot
  s2a        2.4G   /
  s3e        185M   /config
  s3f        2.1G   /var
  s4a        224M   recovery
  s4e        15M

Note above stating Currently booted from: backup (da0s2a). This is the backup partition the unit has currently booted from. We’ll need to rectify this.

Traffic shaping per IPv4 address on Juniper SRX

Fri, 27 Aug 2021 00:18:20 +0100

Limiting bandwidth per IPv4 address on a Juniper SRX. I’ve not done this for IPv6 as of yet. In this example there is a /29 subnet with two addresses requiring bandwidth limits.

We’ll be configuring the following examples:

172.16.0.2 = 100Mbps symmetrical
172.16.0.3 = 25Mbps symmetrical

Interfaces:

WAN = ge-0/0/0
DMZ = ge-0/0/1

Configure queues and schedules
#

Think of the queues as segregated laneways with speed limits. We’re configuring up a queue number and naming it after the speed we’re going to set. This is just a reference name. The SRX already has some queue numbers as default, so we wont interfere with them. We’ll choose some free queues. Queues 6 and 7