Junos Architecture - Processes | Introduction to Juniper and JNCIA Part 13

there are different schools of thought when it comes to operating system design juniper's junos and cisco's ios for example take very different approaches we're going to see the advantages to the junos modular design when it comes to operating systems there are two main designs monolithic and modular the monolithic architecture is very simple all processes including memory management file management device management and process management are contained directly in the kernel this can be used for very specific purposes and it can be very fast too unfortunately there are also downsides the entire operating system uses a single memory space which means that a fault in one component can take down the entire kernel it's also difficult to port to different hardware as the drives are part of the kernel too i've put a link in the description if learning about this kind of thing interests you a modular operating system is a bit different each process operates independently separate from the kernel in its own protected memory space if there's a fault in one process it will not damage another drivers are also independent which means that the operating system can be more easily ported to other hardware overall this is a more modern sophisticated design which improves stability and uptime for comparison reasons let me point out that cisco's traditional ios is a monolithic operating system ios has been around a long time so monolithic is pretty normal considering its age cisco improved on this with ios xe which is using their modern routers and switches it has linux as the base operating system and ios runs as a monolithic application in a container there's a link in the description which explains cisco's operating systems as cows of all things it's actually a really good read i recommend having a look high-end cisco routers run ios xr which like junos is modular everything runs in its own protected memory space this was in fact one of juniper's primary design goals when they created junos separation of modules for stability one of the advantages of this is that we can restart certain processes without restarting the entire device while we're talking about processors let's look at the common ones you can practice with these in the associated lab first we have the chassis process called chassis d this runs shortly after boot up and is responsible for bringing the line cards online as well as interfaces and other hardware components chassis d runs on the re as well as on the pfe you'll notice that most processors end with a d which is short for daemon which is the traditional unix name for a process or service next we have the device control process dcd which manages interfaces this includes encapsulation timers vlans ip addresses and so on if you ever need to troubleshoot this process run show log dcd the management daemon mgd is used for management traffic this includes incoming ssh and telnet requests this also handles commands we send to the device and device configuration rpd the routing protocol daemon manages all routing protocols this includes ospf bgp isis and rip rpd's job includes performing calculations like finding the shortest path through a network and adding routes to the routing table this process is multi-threaded and uses scheduling so it doesn't devote all its time to a single task this is important as it can't be allowed to get too busy working on one thing and then miss some routing updates finally snmpd manages snmp requests and responses as well as snmp traps there are plenty more processes these are just some of the common ones you might come across from time to time in fact let's take a look at them now with this command we can see the name of the process the percentage of the cpu that it's using as well as some other details the restart command lets us restart these processes if we need to in this video you can probably see how an underlying linux or freebsd operating system affects the philosophy that juniper has towards their devices so we've got a good idea around juniper's philosophy on hardware and software architecture the next video changes it up a bit and looks at the structure of firewall filters components that are used for many functions in junos click the video here to get started

Channel: Network Direction

Views: 1,350

Rating: 5 out of 5

Keywords: Network direction, Juniper, Junos, JNCIA, JN0-103, Modular, Monolithic, Hybrid, Architecture, Memory space, Drivers, Kernel, chassisd, Daemon, Dcd, Mgd, Rpd, Snmpd, Processes, web-management

Id: HBwEfmiL0RI

Length: 4min 59sec (299 seconds)

Published: Tue Feb 02 2021