Architecure planes Flashcards
What are the 3 planes on JunOS?
Control
Forwarding
Management
Why are there multiple planes?
Logical separation of tasks
What is in the control plane?
Lives on the Device CPU.
Responsible for;
-All processes that learn of network paths (L2 and L3)
- populating software forwarding tables
- Routing protocol maintenance
- Runs the JunOS OS and daemons
Whats in the Forwarding plane?
Lives on the PFE (Packet forwarding Engine)
- composed of ASIC based hardware and software microcode
- Typically distributed across multiple pieces of hardware in the chassis
- Every linecard has its own PFE…
Rsponsible for quick forwarding using forwarding tables and firewall filters
What is management plane?
Subset of the control plane - runs on the same hardware…
- Controls any process that is used to manage the box;
- ClI via console port
- Telnet/SSH
-SNMP, RESTCONF, Netconf sessions - Incoming locally terminated ICMP
What is transit traffic?
Traffic that is not destined for the device and is routed/switched through the device by the PFE
Could be either Unicast or Multicast
What is exception traffic?
Traffic that for some reason needs to be handled locally on-device.
- Traffic destined to the device - traffic for routing protocols or management for example
- If the IP Options field is set, it will be exception traffic
- ## ICMP - like ping responses, TTL Expired messages
Where is exception traffic proccessed?
Either Management or Control plane - depending what the traffic is.
Where does multicast replication occur?
On the PFE. If needed the traffic is replicated and sent out multiple interfaces without needing to touch the RE
How was legacy JUNOS first delivered?
As a single combined image with all planes running together.
32bit BSD
Images are hardware specific
Ran from 1990’s to 2012
Whats Junos VM? (Stage2 Junos evolution)
virtualised Junos
Still legacy Junos - planes are squished, but we can run it in a VM now.
Launched in 2012
vMX and vSRX are this product.
What was the 3rd stage of Junos Evolution?
What were the benefits?
2017+
Disaggregation.
Separation of PFE and platform code - now running in different BSD VMs running ontop of a Linux hypervisor
The platform specific drivers are now separate so we’re no longer tied to a specific hardware
New APIs
Still talking about everything running together within those VMs.
Benefits:
Breaking platform drivers and RE away from PFE made it way more performant
Hardware independent
per process processor pinning
ISSU!
3rd party tools can now run on the device.
What product used Disaggregated Junos?
NFX series!
What is the final form of Junos evolution?
stage 4 - OS Evolved.
2018+
No more BSD.
Junos has been broken down further, we now have each function broken out into its own application.
Still have PFE and Platform VM separation, but now theres application control and separation too.
New Distributed State infrastructure - the DDS so all the Daemons can write state data in the same place. Makes HA easier as you can more easily retain state between daemon restarts.
What runs OS Evolved?
QTX’s
PTX’s
maybe more, but for the exam just those.
