modular router software?

[nwrGUY]

I have been reading a lot about routers. I understand what a modular router is. It has different ports and slots. You use them to add cards of special types. What does it mean if the router is software is modular? Like this from Extreme Networks:

Modular ExtremeXOS® Operating System (OS) for non-stop operations

[GoldenRabbit]

It means the OS itself is modular. Meaning, you can make changes to specific parts of the system without affecting the other parts. For example, you can make changes to operating systems without affecting the already running system. It also provides better stablity because processes run isolated. If something were to go wrong or crash, it doesn't take down the whole router as a result.

I have never used the Extreme XOS, but we use JunOS on some routers. Since switching from Cisco IOS, we are able to do more things without taking outages. Cisco IOS is considered monolithic in case you ever hear that term. It's the opposite of modular as everything is tied together and requires a restart of the system to make major changes.

[Webmaster]

I've used both JunOS and XOS. The thing I like best about JunOS is the ability to make changes to the configuration (major changes in some cases) and apply it later. I can configure new interfaces or make changes to existing ones and schedule the changes to take place at a later time and date.

JunOS has a great rollback feature as well. The problem with IOS is once you make a change, you hope you didn't mis-configure anything. If you did, you are forced to reboot the device or console to undo the changes. Using JunOS, you can issue the command "commit confirm" which will apply the configuration. After a short time, if you do not aknowledge your changes, it rolls back to the previous configuration automatically. That eliminates the problem of being locked out after an incorrect change. You will not have to console or reboot the device. In most cases, that feature alone is enough to make network enigneers make the switch to a modular OS.

Cisco's new Nexus line includes a modular OS.