4A0-114 Nokia Border Gateway Protocol Fundamentals for Services Free Practice Exam Questions (2025 Updated)

Understanding the Network Topology:

Routers are part of different ASes: Router A and Router B are in AS 65540, Router D is in AS 65550, and Router E is in AS 65560.

To allow Router B to exchange traffic with Router D, proper iBGP (internal BGP) configuration is required within AS 65540.

Configuration Requirements:

The configuration on Router A should include:

Enabling IPv6 family for BGP.

Setting the next-hop-self to ensure that the BGP next-hop is reachable.

Specifying the type as internal to denote an iBGP session.

Configuring the neighbor as Router B's IPv6 address.

Analyzing Options:

Option A: Missing the type internal configuration.

Option B: Missing the family ipv6 configuration.

Option C: Missing both next-hop-self and type internal configurations.

Option D: Correctly includes all necessary commands:

family ipv6

next-hop-self

type internal

neighbor 2001:DB8:2::2

Conclusion:

Option D provides a complete configuration for Router A to enable traffic exchange between Router B and Router D using iBGP with IPv6.

References

Nokia Border Gateway Protocol (BGP) Fundamentals documentation

Best practices for iBGP and eBGP configurations

IPv6 addressing and BGP configurations in multi-AS environments

Policy Statement Analysis: The given policy statement includes an "or" condition for matching prefixes in "List-1" or "List-2".

Action on Match: The action specified for matches is "reject".

Import Policy Behavior: When applied as an import policy, any BGP route that matches either "List-1" or "List-2" will be rejected and not allowed into the BGP table.

References:

Nokia Border Gateway Protocol Fundamentals

Nokia 7750 SR OS BGP Configuration Guide

A type-2 EVPN route update is used to carry host-specific information.

It includes the MAC address of the host and optionally the associated IP address.

This type of update allows for efficient MAC and IP address learning and advertisement within the EVPN.

Therefore, the type-2 EVPN route update carries a host MAC address and optionally the associated IP address.

References:

Nokia Border Gateway Protocol Fundamentals documentation, Section 11.2 on type-2 EVPN route updates.

BGP Peer Discovery: Unlike some other routing protocols (e.g., OSPF, EIGRP), BGP does not use Hello messages to discover peers dynamically. Instead, BGP peers (neighbors) must be manually configured.

TCP Session: For BGP to operate, it requires an underlying TCP connection (port 179) between the two routers.

OPEN Message: The initial BGP message sent after establishing the TCP connection is the OPEN message, which is used to negotiate session parameters and exchange capabilities.

Exterior Routing Protocol: BGP was designed primarily for inter-AS (Autonomous System) routing, making it suitable for internet backbone routing and other exterior routing scenarios.

References:

Nokia BGP Fundamentals Documentation, Chapter on BGP Peer Establishment

RFC 4271 (A Border Gateway Protocol 4), Section 4

When a TCP connection fails to be established with a BGP peer, the BGP state machine goes through several states. The initial state is "Idle". In this state, BGP initializes all resources and awaits a start event. After initiating a TCP connection to the peer, it transitions to the "Connect" state. If the TCP connection attempt is unsuccessful, the state will transition to "Active", where BGP will continue to try to establish the TCP connection.

Idle: BGP is waiting for a start event to initialize a connection.

Connect: BGP is trying to establish a TCP connection.

Active: BGP attempts to establish a connection if the previous TCP connection attempt fails.

Since the question specifies the failure of TCP connection establishment, the valid states are "Idle" and "Active".

ReferencesNokia Border Gateway Protocol Fundamentals, Chapter on BGP States and the BGP Finite State Machine.

A distributed EVPN VPRN service acts as a router for IP packets between customer sites.

It does require two types of interfaces: one towards customer sites (CEs) and another towards the EVPN VPLS for backhaul connectivity.

The configured route target (RT) helps PE routers identify relevant BGP updates.

MP-BGP with the EVPN address family is used to populate the routing table.

Therefore, the statement "It requires two types of interfaces, one towards customer sites and one towards the backhaul VPLS." is FALSE because the backhaul VPLS reference should instead pertain to VPRN backhaul routing.

References:

Nokia Border Gateway Protocol Fundamentals documentation, Section 9.2 on EVPN VPRN interface requirements and configuration.

BGP Message Types: BGP uses several types of messages for various functions: Open, Update, Notification, and Keep-Alive.

Keep-Alive Message: This type of message is sent periodically to verify connectivity between BGP peers. After the BGP session is established with Open messages, Keep-Alive messages ensure the session remains active and monitor the health of the connection.

Connectivity Verification: During the establishment of a BGP session, the Open message is initially used. Post-establishment, Keep-Alive messages are sent at regular intervals to maintain the connection and to verify that both peers are still reachable and operational.

References:

Nokia BGP Fundamentals Documentation, Chapter on BGP Message Types

RFC 4271 (A Border Gateway Protocol 4), Sections 4.2 and 4.4

The BGP import policy "north-and-south" on R5 checks the community attribute of incoming routes.

If the community matches "65200:1", it sets the local preference to 20.

Since R1 advertises the prefix 140.100.1.0/24 with a community of "65200:1", R5 will apply the policy action.

Therefore, the prefix's local preference is set to 20.

References:

Nokia Border Gateway Protocol Fundamentals documentation, Section 5.2 on BGP policies.

Route reflectors (RR) are used in BGP to reduce the number of iBGP sessions required within an Autonomous System (AS). Here are key points about route reflectors:

B. True: A route reflector can have both iBGP and eBGP clients, allowing it to propagate routes between internal and external peers.

C. True: A route reflector disables the iBGP split-horizon rule for its clients, allowing it to propagate routes received from one iBGP client to other iBGP clients.

D. True: Route reflectors reduce the number of iBGP sessions required in an AS by allowing clients to form iBGP sessions only with the route reflector instead of with every other iBGP peer.

The false statement is:

A. False: A full iBGP mesh is not required among route reflectors themselves. Instead, route reflectors can form a partial mesh or hierarchical structure to propagate routes efficiently.

ReferencesNokia Border Gateway Protocol Fundamentals, Chapter on Route Reflectors.

Route reflector clusters help in organizing route reflectors within an AS to manage scalability and redundancy. Here are key points about route reflector clusters:

A. True: Multiple clusters may be configured within an AS to improve scalability and load distribution.

B. False: Within an AS, route reflectors belonging to different clusters do need to be fully-meshed among themselves to ensure proper route propagation and to avoid routing loops.

C. True: A router can be the client of multiple route reflectors within its AS, providing redundancy and load balancing.

D. True: When a route reflector reflects a route, it adds its cluster ID to the Cluster_list attribute to prevent routing loops and ensure proper route propagation.

ReferencesNokia Border Gateway Protocol Fundamentals

IPv6 BGP Session Requirements: To establish an IPv6 BGP session, the configuration must include the IPv6 addresses of the neighbors and the appropriate family settings.

Option Analysis:

Option A: Incorrect. The configuration does not match typical BGP IPv6 configuration standards for Nokia routers.

Option B: Incorrect. The configuration is incomplete for establishing an IPv6 BGP session.

Option C: Correct. The configuration includes the appropriate neighbor IPv6 address and family settings required to establish an IPv6 BGP session.

Option D: Incorrect. The configuration has errors or missing components needed for a proper IPv6 BGP session.

Conclusion: Option C provides the correct configuration necessary to establish an IPv6 BGP session between router A and router B.

References:

Nokia Border Gateway Protocol Fundamentals

Nokia 7750 SR OS BGP Configuration Guide

Route Reflector (RR) Basics: In a BGP network, route reflectors help reduce the need for a full mesh of iBGP sessions. Each route reflector assigns a cluster ID to identify the cluster it belongs to and avoid routing loops.

Cluster-ID: When multiple route reflectors have the same cluster ID, a router receiving routes from these reflectors will use the cluster ID to identify if the routes have been advertised by the same cluster.

Duplicate Routes: If a route is received from different route reflectors with the same cluster ID, the receiving router (RA) will detect this as a duplicate advertisement from the same cluster.

Invalid Route Handling: BGP protocol dictates that routes received from the same cluster ID will be flagged as invalid to prevent potential routing loops.

Conclusion: Router RA flags both updates for prefix 192.168.1.0/27 received from RR1 and RR2 as invalid because they have the same cluster ID.

References:

Nokia Border Gateway Protocol Fundamentals

RFC 4456 - BGP Route Reflection: An Alternative to Full Mesh iBGP