Question 810
After Bluebird Infrastructure deploys PIM-SSM source-specific join to let subscribers request an explicitly selected multicast source and group pair, the primary acceptance check passes (the forwarding entry matches the requested source and group without RP discovery). What remaining operational risk should still be part of the design review?
- Application and switch support for IGMPv3 is required.
- The receiver must know and signal the intended multicast source.
- Split-horizon and aliasing behavior must be correct to avoid duplicate forwarding.
- Stateful firewall and return-path policies must match the breakout design.
Explanation
Correct Answer
B:The relevant boundary of PIM-SSM source-specific join is that the receiver must know and signal the intended multicast source. Passing the acceptance test does not eliminate this residual operational risk.
Incorrect Answers
A:This concern applies to IGMPv3 inclusion filtering in a different scenario where operators need to request multicast only from one specified source at the IPv4 receiver edge. For the deployed PIM-SSM source-specific join approach, the relevant caution is instead that the receiver must know and signal the intended multicast source.
C:This concern applies to EVPN multihomed all-active Ethernet segment in a different scenario where operators need to let a CE use two provider edges without losing its active Ethernet path on one PE failure. For the deployed PIM-SSM source-specific join approach, the relevant caution is instead that the receiver must know and signal the intended multicast source.
D:This concern applies to controlled Internet breakout in a different scenario where operators need to provide Internet access for an L3VPN tenant without leaking private customer prefixes. For the deployed PIM-SSM source-specific join approach, the relevant caution is instead that the receiver must know and signal the intended multicast source.
Question 811
Horizon Exchange must support a many-to-many multicast service using appropriate shared distribution state. The operator is comparing several service-provider methods. Which design or control directly addresses that stated requirement?
- PIM-SSM source-specific join
- EVPN MAC mobility control
- PIM bidirectional shared delivery
- traffic policing excess handling
Explanation
Correct Answer
C:PIM bidirectional shared delivery matches this requirement: the team should configure supported bidirectional PIM and corresponding RP infrastructure. A relevant outcome would be that forwarding follows the bidirectional shared tree without source-specific shortest path switching.
Incorrect Answers
A:PIM-SSM source-specific join instead addresses a different condition: let subscribers request an explicitly selected multicast source and group pair. It would instead require you to use SSM with source-aware membership such as IGMPv3 on supported receivers, not the stated goal to support a many-to-many multicast service using appropriate shared distribution state.
B:EVPN MAC mobility control instead addresses a different condition: maintain forwarding when a customer virtual machine moves between EVPN access PEs. It would instead require you to apply MAC mobility and sequence handling for newly advertised locations, not the stated goal to support a many-to-many multicast service using appropriate shared distribution state.
D:traffic policing excess handling instead addresses a different condition: enforce a hard contracted rate with an explicit action for out-of-profile traffic. It would instead require you to use a policer with appropriate committed rate and drop or remark behavior, not the stated goal to support a many-to-many multicast service using appropriate shared distribution state.
Question 812
At Cedar Wireless, the engineering change is approved for PIM bidirectional shared delivery. The specific goal is to support a many-to-many multicast service using appropriate shared distribution state. Which implementation step belongs in this change plan?
- Use SSM with source-aware membership such as IGMPv3 on supported receivers.
- Apply MAC mobility and sequence handling for newly advertised locations.
- Use a policer with appropriate committed rate and drop or remark behavior.
- Configure supported bidirectional PIM and corresponding RP infrastructure.
Explanation
Correct Answer
D:Implementing PIM bidirectional shared delivery requires the operator to configure supported bidirectional PIM and corresponding RP infrastructure. This makes the required goal testable using evidence that forwarding follows the bidirectional shared tree without source-specific shortest path switching.
Incorrect Answers
A:The proposed step is for PIM-SSM source-specific join, whose purpose is to let subscribers request an explicitly selected multicast source and group pair. It would not perform the necessary PIM bidirectional shared delivery operation: configure supported bidirectional PIM and corresponding RP infrastructure.
B:The proposed step is for EVPN MAC mobility control, whose purpose is to maintain forwarding when a customer virtual machine moves between EVPN access PEs. It would not perform the necessary PIM bidirectional shared delivery operation: configure supported bidirectional PIM and corresponding RP infrastructure.
C:The proposed step is for traffic policing excess handling, whose purpose is to enforce a hard contracted rate with an explicit action for out-of-profile traffic. It would not perform the necessary PIM bidirectional shared delivery operation: configure supported bidirectional PIM and corresponding RP infrastructure.
Question 813
Willow Regional has deployed PIM bidirectional shared delivery to support a many-to-many multicast service using appropriate shared distribution state. The implementation step was to configure supported bidirectional PIM and corresponding RP infrastructure. Which observation demonstrates that the requested service is working?
- Forwarding follows the bidirectional shared tree without source-specific shortest path switching.
- The forwarding entry matches the requested source and group without RP discovery.
- Remote sites converge on the latest legitimate MAC attachment point.
- Excess traffic is counted and treated per policy rather than queued indefinitely.
Explanation
Correct Answer
A:For PIM bidirectional shared delivery, successful verification means that forwarding follows the bidirectional shared tree without source-specific shortest path switching. That evidence directly tests whether the provider can support a many-to-many multicast service using appropriate shared distribution state after deployment.
Incorrect Answers
B:The observation would verify PIM-SSM source-specific join under the separate requirement to let subscribers request an explicitly selected multicast source and group pair. It does not demonstrate the needed PIM bidirectional shared delivery result: forwarding follows the bidirectional shared tree without source-specific shortest path switching.
C:The observation would verify EVPN MAC mobility control under the separate requirement to maintain forwarding when a customer virtual machine moves between EVPN access PEs. It does not demonstrate the needed PIM bidirectional shared delivery result: forwarding follows the bidirectional shared tree without source-specific shortest path switching.
D:The observation would verify traffic policing excess handling under the separate requirement to enforce a hard contracted rate with an explicit action for out-of-profile traffic. It does not demonstrate the needed PIM bidirectional shared delivery result: forwarding follows the bidirectional shared tree without source-specific shortest path switching.
Question 814
While troubleshooting PIM bidirectional shared delivery at Atlas Backbone, the intended acceptance outcome is still missing: forwarding follows the bidirectional shared tree without source-specific shortest path switching. Which fault condition should be investigated first for this particular design?
- An any-source IGMPv2 membership is used expecting source-specific filtering.
- PIM-SM source tree behavior is expected to apply to BIDIR shared-tree traffic.
- Older advertisements repeatedly overwrite the new location and cause oscillation.
- Shaping is used where immediate excess-drop enforcement was required.
Explanation
Correct Answer
B:The suspected defect directly frustrates PIM bidirectional shared delivery: PIM-SM source tree behavior is expected to apply to BIDIR shared-tree traffic. Correcting it should allow verification that forwarding follows the bidirectional shared tree without source-specific shortest path switching.
Incorrect Answers
A:This defect belongs to PIM-SSM source-specific join, where the affected outcome is to let subscribers request an explicitly selected multicast source and group pair. It is not the direct failure mode identified for the PIM bidirectional shared delivery design in this case: PIM-SM source tree behavior is expected to apply to BIDIR shared-tree traffic.
C:This defect belongs to EVPN MAC mobility control, where the affected outcome is to maintain forwarding when a customer virtual machine moves between EVPN access PEs. It is not the direct failure mode identified for the PIM bidirectional shared delivery design in this case: PIM-SM source tree behavior is expected to apply to BIDIR shared-tree traffic.
D:This defect belongs to traffic policing excess handling, where the affected outcome is to enforce a hard contracted rate with an explicit action for out-of-profile traffic. It is not the direct failure mode identified for the PIM bidirectional shared delivery design in this case: PIM-SM source tree behavior is expected to apply to BIDIR shared-tree traffic.
Question 815
After Starlight IP Services deploys PIM bidirectional shared delivery to support a many-to-many multicast service using appropriate shared distribution state, the primary acceptance check passes (forwarding follows the bidirectional shared tree without source-specific shortest path switching). What remaining operational risk should still be part of the design review?
- The receiver must know and signal the intended multicast source.
- Rapidly flapping customer MACs can still trigger mobility dampening.
- Bidirectional mode has distinct DF and topology design requirements.
- Burst sizing affects how many short traffic spikes are permitted.
Explanation
Correct Answer
C:The relevant boundary of PIM bidirectional shared delivery is that bidirectional mode has distinct DF and topology design requirements. Passing the acceptance test does not eliminate this residual operational risk.
Incorrect Answers
A:This concern applies to PIM-SSM source-specific join in a different scenario where operators need to let subscribers request an explicitly selected multicast source and group pair. For the deployed PIM bidirectional shared delivery approach, the relevant caution is instead that bidirectional mode has distinct DF and topology design requirements.
B:This concern applies to EVPN MAC mobility control in a different scenario where operators need to maintain forwarding when a customer virtual machine moves between EVPN access PEs. For the deployed PIM bidirectional shared delivery approach, the relevant caution is instead that bidirectional mode has distinct DF and topology design requirements.
D:This concern applies to traffic policing excess handling in a different scenario where operators need to enforce a hard contracted rate with an explicit action for out-of-profile traffic. For the deployed PIM bidirectional shared delivery approach, the relevant caution is instead that bidirectional mode has distinct DF and topology design requirements.
Question 816
Northstar Carrier must request multicast only from one specified source at the IPv4 receiver edge. The operator is comparing several service-provider methods. Which design or control directly addresses that stated requirement?
- MLD IPv6 membership
- L3VPN label blackhole diagnosis
- EVPN single-active access design
- IGMPv3 inclusion filtering
Explanation
Correct Answer
D:IGMPv3 inclusion filtering matches this requirement: the team should send appropriate IGMPv3 INCLUDE-mode membership state. A relevant outcome would be that the last-hop router forwards only the approved source/group traffic.
Incorrect Answers
A:MLD IPv6 membership instead addresses a different condition: enable an IPv6 receiver to join multicast groups on the first-hop router. It would instead require you to activate the appropriate MLD behavior on the IPv6 multicast access, not the stated goal to request multicast only from one specified source at the IPv4 receiver edge.
B:L3VPN label blackhole diagnosis instead addresses a different condition: investigate a VPNv4 route that exists in BGP but does not carry packets end to end. It would instead require you to check transport label and VPN service label resolution from ingress to egress, not the stated goal to request multicast only from one specified source at the IPv4 receiver edge.
C:EVPN single-active access design instead addresses a different condition: make only one provider edge forward traffic for a protected customer Ethernet segment. It would instead require you to configure supported single-active EVPN multihoming and designated-forwarder behavior, not the stated goal to request multicast only from one specified source at the IPv4 receiver edge.
Question 817
At Orion Transit, the engineering change is approved for IGMPv3 inclusion filtering. The specific goal is to request multicast only from one specified source at the IPv4 receiver edge. Which implementation step belongs in this change plan?
- Send appropriate IGMPv3 INCLUDE-mode membership state.
- Activate the appropriate MLD behavior on the IPv6 multicast access.
- Check transport label and VPN service label resolution from ingress to egress.
- Configure supported single-active EVPN multihoming and designated-forwarder behavior.
Explanation
Correct Answer
A:Implementing IGMPv3 inclusion filtering requires the operator to send appropriate IGMPv3 INCLUDE-mode membership state. This makes the required goal testable using evidence that the last-hop router forwards only the approved source/group traffic.
Incorrect Answers
B:The proposed step is for MLD IPv6 membership, whose purpose is to enable an IPv6 receiver to join multicast groups on the first-hop router. It would not perform the necessary IGMPv3 inclusion filtering operation: send appropriate IGMPv3 INCLUDE-mode membership state.
C:The proposed step is for L3VPN label blackhole diagnosis, whose purpose is to investigate a VPNv4 route that exists in BGP but does not carry packets end to end. It would not perform the necessary IGMPv3 inclusion filtering operation: send appropriate IGMPv3 INCLUDE-mode membership state.
D:The proposed step is for EVPN single-active access design, whose purpose is to make only one provider edge forward traffic for a protected customer Ethernet segment. It would not perform the necessary IGMPv3 inclusion filtering operation: send appropriate IGMPv3 INCLUDE-mode membership state.
Question 818
Meridian Networks has deployed IGMPv3 inclusion filtering to request multicast only from one specified source at the IPv4 receiver edge. The implementation step was to send appropriate IGMPv3 INCLUDE-mode membership state. Which observation demonstrates that the requested service is working?
- IPv6 group membership state is present and traffic is forwarded to the receiver.
- The last-hop router forwards only the approved source/group traffic.
- The programmed FIB includes valid next hop and VPN egress label disposition.
- One active access PE forwards while backup takes over after failover.
Explanation
Correct Answer
B:For IGMPv3 inclusion filtering, successful verification means that the last-hop router forwards only the approved source/group traffic. That evidence directly tests whether the provider can request multicast only from one specified source at the IPv4 receiver edge after deployment.
Incorrect Answers
A:The observation would verify MLD IPv6 membership under the separate requirement to enable an IPv6 receiver to join multicast groups on the first-hop router. It does not demonstrate the needed IGMPv3 inclusion filtering result: the last-hop router forwards only the approved source/group traffic.
C:The observation would verify L3VPN label blackhole diagnosis under the separate requirement to investigate a VPNv4 route that exists in BGP but does not carry packets end to end. It does not demonstrate the needed IGMPv3 inclusion filtering result: the last-hop router forwards only the approved source/group traffic.
D:The observation would verify EVPN single-active access design under the separate requirement to make only one provider edge forward traffic for a protected customer Ethernet segment. It does not demonstrate the needed IGMPv3 inclusion filtering result: the last-hop router forwards only the approved source/group traffic.
Question 819
While troubleshooting IGMPv3 inclusion filtering at Kestrel Broadband, the intended acceptance outcome is still missing: the last-hop router forwards only the approved source/group traffic. Which fault condition should be investigated first for this particular design?
- IPv4 IGMP signaling is used expecting IPv6 MLD state to appear.
- BGP reachability alone is accepted as proof that labeled forwarding is correct.
- IGMPv2 group-only membership is treated as if it encoded a source filter.
- Both PEs forward simultaneously despite a single-active customer requirement.
Explanation
Correct Answer
C:The suspected defect directly frustrates IGMPv3 inclusion filtering: IGMPv2 group-only membership is treated as if it encoded a source filter. Correcting it should allow verification that the last-hop router forwards only the approved source/group traffic.
Incorrect Answers
A:This defect belongs to MLD IPv6 membership, where the affected outcome is to enable an IPv6 receiver to join multicast groups on the first-hop router. It is not the direct failure mode identified for the IGMPv3 inclusion filtering design in this case: IGMPv2 group-only membership is treated as if it encoded a source filter.
B:This defect belongs to L3VPN label blackhole diagnosis, where the affected outcome is to investigate a VPNv4 route that exists in BGP but does not carry packets end to end. It is not the direct failure mode identified for the IGMPv3 inclusion filtering design in this case: IGMPv2 group-only membership is treated as if it encoded a source filter.
D:This defect belongs to EVPN single-active access design, where the affected outcome is to make only one provider edge forward traffic for a protected customer Ethernet segment. It is not the direct failure mode identified for the IGMPv3 inclusion filtering design in this case: IGMPv2 group-only membership is treated as if it encoded a source filter.
Question 820
After Harbor Metro deploys IGMPv3 inclusion filtering to request multicast only from one specified source at the IPv4 receiver edge, the primary acceptance check passes (the last-hop router forwards only the approved source/group traffic). What remaining operational risk should still be part of the design review?
- MLD querier and PIMv6 configuration must both be consistent.
- Packet loss can reflect core MTU or data-plane policy even with labels installed.
- Failover convergence remains limited by Ethernet segment state timing.
- Application and switch support for IGMPv3 is required.
Explanation
Correct Answer
D:The relevant boundary of IGMPv3 inclusion filtering is that application and switch support for IGMPv3 is required. Passing the acceptance test does not eliminate this residual operational risk.
Incorrect Answers
A:This concern applies to MLD IPv6 membership in a different scenario where operators need to enable an IPv6 receiver to join multicast groups on the first-hop router. For the deployed IGMPv3 inclusion filtering approach, the relevant caution is instead that application and switch support for IGMPv3 is required.
B:This concern applies to L3VPN label blackhole diagnosis in a different scenario where operators need to investigate a VPNv4 route that exists in BGP but does not carry packets end to end. For the deployed IGMPv3 inclusion filtering approach, the relevant caution is instead that application and switch support for IGMPv3 is required.
C:This concern applies to EVPN single-active access design in a different scenario where operators need to make only one provider edge forward traffic for a protected customer Ethernet segment. For the deployed IGMPv3 inclusion filtering approach, the relevant caution is instead that application and switch support for IGMPv3 is required.
Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) (350-501) Practice Tests