March 2008
Intermediate to advanced
816 pages
25h 6m
English
Content preview from JUNOS Enterprise RoutingBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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JUNOS Overview
JUNOS software is cool. It just is. The designers of JUNOS software put tremendous thought into making a stable, robust, and scalable operating system that would be a positive for the router. They were able to learn from previous vendors’ mistakes, and created an OS that other companies will forever use as their model.
The core philosophy of JUNOS software was to create a modular and stable operating system. The modularization was created by the use of software daemons, and the stability was achieved by choosing a well-known, open source, and stable kernel of FreeBSD. This kernel is usually hidden to the user, but many features of FreeBSD have been ported to the command line of JUNOS. The kernel also maintains the forwarding table synchronization between the RE and the PFE.
Riding on top of the kernel are all the fully independent software processes for routing, CLI, interfaces, and so forth. Figure 1-2 shows a small subset of these processes; you can show a complete list in the router by issuing a show system processes command. These processes are fully independent, so a failure of one process will not affect the other. For example, Figure 1-2 shows the Simple Network Management Protocol (SNMP) process pulling information from the interface, chassis, and routing processes. If this SNMP process fails or contains a software bug, it affects only this process and not the others. This is a major shift from other routing vendors that operated monolithic code where one change ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.