Junos Architecture (Processes)

Junos Architecture (Processes)




Operating systems can be classified as modular, or monolithic.

Monolithic operating systems have the kernel manage all functions. This is fast, but unfortunately, one area of code can affect another area of code.

Modular operating systems split functions into completely separate and independent processes. If there’s a fault in one process, it will not affect another.

Junos is a modular operating system.

Common processes include:

  • chassisd – Starts up PFE’s, interfaces, and related hardware
  • dcd – Manages devices
  • mgd – Device management (SSH, web, CLI, etc)
  • rpd – Manages routing protocols (a multithreaded process)
  • snmpd – responds to SNMP polling, sends SNMP trap messages

Command Summary

Command Mode Description
show log dcd Operational Troubleshoot the device control daemon
show system processes extensive Operational Shows a full list of processes
restart web-management Operational Restart the web management daemon

Additional References

What is a monolithic operating system

What is a monolithic operating system

Using Cows to Explain the Differences of the Cisco Operating Systems


Junos OS Routing Engine Components and Processes


Junos OS Routing Processes


Leave a Reply