JN0-280 Exam Dumps : Data Center, Associate (JNCIA-DC)

AMAC address of FF-FF-FF-FF-FF-FFis the Ethernetbroadcast address. When a switch receives a frame with this destination MAC address, it is required to forward the frame to all interfaces except the one it was received on.

Step-by-Step Breakdown:

Broadcast Frame Handling:When a frame with the broadcast MAC address is received, the switch will flood it out of all active ports that belong to the same VLAN as the incoming frame. The broadcast frame is not sent back out of the ingress interface (the interface where the frame was originally received).

Purpose of Flooding:Broadcasting is used to ensure that the frame reaches all devices within the broadcast domain (all devices within the same VLAN), which may not have a specific entry for the MAC address in their MAC address table.

Juniper Reference:

Layer 2 Frame Forwarding: Juniper switches flood broadcast frames to all ports in the same VLAN, except the port the frame was received on.

In aVirtual Chassis(VC) configuration, multiple Juniper switches are interconnected to form a single logical device. Each member switch in the Virtual Chassis plays a specific role.

Step-by-Step Breakdown:

Line Card Role:

Member switches acting asline cardsprovide additional ports for traffic forwarding but do not perform control or routing functions. These switches depend on the routing engine to handle control-plane tasks.

Routing Engine Role:

A switch in therouting-enginerole is responsible for control-plane operations such as routing protocol management and control of the Virtual Chassis.

Virtual Chassis Roles:

Master Routing Engine: Handles control-plane functions and manages the entire Virtual Chassis.

Backup Routing Engine: Takes over if the master fails.

Line Card: Provides additional ports and handles data-plane operations.

Juniper Reference:

Virtual Chassis: In a five-member Virtual Chassis, multiple switches act asline cards, while one or more switches are designated as therouting engines(master and backup).

In OSPF, routers exchange link-state information in different stages to establish full adjacency. TheMTU sizeis checked during theExchangestate.

Step-by-Step Breakdown:

OSPF Adjacency Process:

OSPF routers go through multiple stages when forming an adjacency:Down,Init,2-Way,ExStart,Exchange,Loading, andFull.

Exchange State:

During theExchangestate, OSPF routers exchangeDatabase Description (DBD)packets to describe their link-state databases. TheMTU sizeis checked at this stage to ensure both routers can successfully exchange these packets without fragmentation.

If there is anMTU mismatch, the routers may fail to proceed past the Exchange state.

Juniper Reference:

MTU Checking in OSPF: Junos uses the Exchange state to check for MTU mismatches, ensuring that routers can properly exchange database information without packet fragmentation issues.