JunOS

From Juniper Clue

Juniper JUNOS is the operating system powering virtually all Juniper routing/switching products. At the time of the release, it became the only purpose-built control plane in the market, which allowed for high degree of instrumentation and modularity. Over the time, JUNOS gained structurally complex functionality, such as non-stop routing (NSR), in-service software upgrades (ISSU), horizontal modularity (JUNOS SDK for 3rd party developers aka JUNOS Space).

The JunOS operating system is based on FreeBSD, with significant modifications. JUNOS contains all the standard FreeBSD user programs and tools and allows FreeBSD binaries to run, but the opposite is not true. Juniper appears to have the ability to sync their network OS to main branches of FreeBSD development:

• JUNOS prior to 5.0 was based on FreeBSD 2.2.6.
• JUNOS between 5.0 and 7.2 (inclusive) is based on FreeBSD 4.2.
• JUNOS 7.3 and higher is based on FreeBSD 4.10.
• JUNOS 8.5 is based on FreeBSD 6.1

In addition to having the features typical to the carrier-grade network OS, JUNOS also is known for its highly regular and well-regressed release schedule (see history of JUNOS releases). As a general rule, mainline JUNOS release happens four times a year and is (sometimes) followed with multiple "regress" releases incorporating only bugfixes. New feature development happens only at the head of the development train.

Also, see: JunOS 7.3 kldstat. Snapshot of JUNOS 4.2 kernel config.