Nokia 4A0-100 Exam Dumps

VLAN Stacking, also known as Q-in-Q tunneling, is a technology that allows multiple customers to use overlapping VLAN IDs while being transported over a shared service provider network.

Key Concepts:

Customer VLAN (C-VLAN): The VLAN used by the customer in their own network.

Service VLAN (S-VLAN): The VLAN used by the service provider to encapsulate the customer VLAN.

When VLAN stacking is applied:

A customer's Ethernet frame already tagged with a C-VLAN is encapsulated with an additional outer S-VLAN tag.

This way, multiple customers can use the same C-VLAN ID, but remain isolated by the unique S-VLAN assigned to them by the service provider.

Why Other Options Are Incorrect:

A . VLAN Trunking: Used to carry multiple VLANs over a single physical link but doesn't allow reuse of VLAN IDs across customers.

C . VLAN Tagging: Refers to the general process of adding a VLAN tag; it doesn't provide the isolation needed across shared infrastructure.

D . VLAN Routing: Refers to Layer 3 routing between VLANs, not to ID reuse or transport over a shared provider backbone.

Nokia Service Architecture and VPNs Study Guide -- Section: ''Q-in-Q VLAN Stacking''

IEEE 802.1ad Standard -- Provider Bridges (Q-in-Q)

The Ingress Label Edge Router (LER) is the first router that:

Receives an unlabeled IP packet.

Applies an MPLS label based on its forwarding decision.

Forwards it into the MPLS core.

Option A is correct -- Ingress LER does MPLS label push.

Option B (Egress LER) -- removes labels at the end of the path.

Option C (LSR) -- switches labels, but doesn't push them onto unlabeled packets.

Option D -- is not a specific MPLS role.

Nokia IP/MPLS Fundamentals Guide -- Label Operations

RFC 3031 -- MPLS Architecture

VPLS (Virtual Private LAN Service) is a Layer 2 VPN service that emulates a bridged Ethernet LAN across an MPLS/IP network.

Learns MAC addresses dynamically from:

SAPs (Service Access Points)

SDPs (Service Distribution Points)

Maintains a Forwarding Database (FDB) per VPLS instance.

For unknown MAC destinations, a VPLS floods the frame to all other sites -- just like a regular Ethernet switch.

Option C is FALSE -- VPLS does NOT discard unknown MACs; it floods them.

Nokia VPLS Services Guide -- Learning and Forwarding

Nokia SRA Study Guide -- VPLS Operation

Nokia MPLS Fundamentals Guide -- Chapter: ''Label Operations (Push, Swap, Pop)''

Nokia SRA Study Guide -- Ingress/Egress LER roles in MPLS

In Nokia SR OS, event logging allows the router to report system events, alarms, and operational changes to external systems or users. The valid logging destinations include:

SNMP -- Used to send traps or informs to SNMP managers.

Syslog -- Sends logs to centralized syslog servers, a standard for log management.

NETCONF -- Can be used for event notification in model-driven management setups, although it is more frequently used for configuration and state management.

However, BOF (Boot Options File) is not a valid logging destination. The BOF is used to store critical system boot configurations, such as:

Which image to boot from

Network interface settings

Auto-boot parameters

BOF plays no role in the logging infrastructure.

Nokia SR OS Fundamentals Guide -- Section: ''Event Logging''

Nokia SRA Study Guide -- Chapter: 'Logging and Event Monitoring'