RFE, PFE, and FEB Part Deux

As we forge on, we will now talk about the final part of the PFE. Packet buffering, queuing, and filtering are accomplished through the compact Forwarding Engine Board or cFEB.



"Would you like one, two, or three cFEBs With That?"

• The M7i has a single cFEB only


• The M10i has a primary and backup cFEB


• The M120 has six cFEBs and can support N+1 redundancy

PICs can only be used in M and T series routers.

"The software based J-Series Router"

Previously we had explored the separation in Juniper routing platforms of the control and forwarding planes. The J-series router unlike M or T-Series accomplished the separation in software through a virtualized thread. But, just because the PFE is virtualized does not mean we are sans interfaces.

Acronyms of the Moment:

PIM: Physical Interface Module (J-Series only)

EPIM: Enhanced Physical Interface Module (Higher speeds supported, J-Series only, and specific slot position)

Who has PIMs?

• J2320
• J2350
• J4350
• J6350

The above mentioned J-Sereies routers are all Enterprise class routers. The M and T series are usually used as core, backbone, or aggregator routers.

"Who Knows? JUNOS!"

JUNOS the operating system that runs on Juniper routers is built in a modular robust way using FreeBSD Unix.

• Single image of JUNOS for all M/T and J series routers regardless of model number.
• JUNOS is modular through the use of software daemons
• Kernel is transparent to user but many unix-like commands exist in the CLI
• Fully independent software processes for control of routing, CLI and so on.
• List processes with show system processes

A note on processes and the J-Series...

The major difference in daemon processes for the J-series is the fwdd daemon (Forwarding Devices Daemon) which is the software PFE.

Onward to CLI!