Chapter 1 JunOS Fondamentals

Question 1

Routing engine

Answer 1

A routing engine is the control plane of the device handling processes/daemons such as RDP, SSH and the management of CPU and memory

Question 2

fxp1

Answer 2

It’s the internal interface/L2 switch in between linecards and routing engine

Question 3

Linecard

Answer 3

Linecards are the forwarding/data plane of the device, they receive the forwarding table from the routing engine and handle the traffic not destined directly to the device. There are multiple linecards in each device

Question 4

JunOS processes

Answer 4

RDP -> handles routing, created the forwarding table
MGD -> Management daemon, manage ssh and the CLI
DCD -> Device configuration daemon, gets cli commands and change
config
ChassisD -> handles linecards through the fxp1

Question 5

Linecards possible names

Answer 5

FPC Flexible PIC oncentrators (PIC = Physical interface card)
DPD Dense port concentrators
MPC Modular port concentrators

Question 6

Transit vs local host traffic

Answer 6

Transit traffic is managed by the linecards using the forwarding table
Local host traffic arrive to the linecards that pass it to the RE that will manage it

Question 7

Transit e localhost traffic exceptions

Answer 7

• TTL Expires are managed by the linecards
• Network unreachable managed by the linecards as they won’t find
  an entry in the forwarding table for the destination
• Firewall configured (ACL) the deny of the traffic is applied on the
  fxp1