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.
Question 821
Summit Service Provider must enable an IPv6 receiver to join multicast groups on the first-hop router. The operator is comparing several service-provider methods. Which design or control directly addresses that stated requirement?
- MLD IPv6 membership
- IGMPv3 inclusion filtering
- 802.1ah provider backbone bridging
- EVPN route target matching
Explanation
Correct Answer
A:MLD IPv6 membership matches this requirement: the team should activate the appropriate MLD behavior on the IPv6 multicast access. A relevant outcome would be that IPv6 group membership state is present and traffic is forwarded to the receiver.
Incorrect Answers
B:IGMPv3 inclusion filtering instead addresses a different condition: request multicast only from one specified source at the IPv4 receiver edge. It would instead require you to send appropriate IGMPv3 INCLUDE-mode membership state, not the stated goal to enable an IPv6 receiver to join multicast groups on the first-hop router.
C:802.1ah provider backbone bridging instead addresses a different condition: reduce provider core visibility into customer MAC addresses for a large Ethernet service. It would instead require you to apply PBB service encapsulation with backbone MAC and service identifiers where supported, not the stated goal to enable an IPv6 receiver to join multicast groups on the first-hop router.
D:EVPN route target matching instead addresses a different condition: restrict the import of BGP EVPN routes to the correct tenant service. It would instead require you to configure the intended import/export route target set for each EVI, not the stated goal to enable an IPv6 receiver to join multicast groups on the first-hop router.
Question 822
At Ridgeway Networks, the engineering change is approved for MLD IPv6 membership. The specific goal is to enable an IPv6 receiver to join multicast groups on the first-hop router. 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.
- Apply PBB service encapsulation with backbone MAC and service identifiers where supported.
- Configure the intended import/export route target set for each EVI.
Explanation
Correct Answer
B:Implementing MLD IPv6 membership requires the operator to activate the appropriate MLD behavior on the IPv6 multicast access. This makes the required goal testable using evidence that IPv6 group membership state is present and traffic is forwarded to the receiver.
Incorrect Answers
A:The proposed step is for IGMPv3 inclusion filtering, whose purpose is to request multicast only from one specified source at the IPv4 receiver edge. It would not perform the necessary MLD IPv6 membership operation: activate the appropriate MLD behavior on the IPv6 multicast access.
C:The proposed step is for 802.1ah provider backbone bridging, whose purpose is to reduce provider core visibility into customer MAC addresses for a large Ethernet service. It would not perform the necessary MLD IPv6 membership operation: activate the appropriate MLD behavior on the IPv6 multicast access.
D:The proposed step is for EVPN route target matching, whose purpose is to restrict the import of BGP EVPN routes to the correct tenant service. It would not perform the necessary MLD IPv6 membership operation: activate the appropriate MLD behavior on the IPv6 multicast access.
Question 823
Lakeside Transport has deployed MLD IPv6 membership to enable an IPv6 receiver to join multicast groups on the first-hop router. The implementation step was to activate the appropriate MLD behavior on the IPv6 multicast access. Which observation demonstrates that the requested service is working?
- The last-hop router forwards only the approved source/group traffic.
- The core switches backbone encapsulation while customer identities stay at the edge.
- IPv6 group membership state is present and traffic is forwarded to the receiver.
- Authorized routes appear only in the matching customer service tables.
Explanation
Correct Answer
C:For MLD IPv6 membership, successful verification means that IPv6 group membership state is present and traffic is forwarded to the receiver. That evidence directly tests whether the provider can enable an IPv6 receiver to join multicast groups on the first-hop router after deployment.
Incorrect Answers
A:The observation would verify IGMPv3 inclusion filtering under the separate requirement to request multicast only from one specified source at the IPv4 receiver edge. It does not demonstrate the needed MLD IPv6 membership result: IPv6 group membership state is present and traffic is forwarded to the receiver.
B:The observation would verify 802.1ah provider backbone bridging under the separate requirement to reduce provider core visibility into customer MAC addresses for a large Ethernet service. It does not demonstrate the needed MLD IPv6 membership result: IPv6 group membership state is present and traffic is forwarded to the receiver.
D:The observation would verify EVPN route target matching under the separate requirement to restrict the import of BGP EVPN routes to the correct tenant service. It does not demonstrate the needed MLD IPv6 membership result: IPv6 group membership state is present and traffic is forwarded to the receiver.
Question 824
While troubleshooting MLD IPv6 membership at Coastal Communications, the intended acceptance outcome is still missing: IPv6 group membership state is present and traffic is forwarded to the receiver. Which fault condition should be investigated first for this particular design?
- IGMPv2 group-only membership is treated as if it encoded a source filter.
- The provider core learns every subscriber MAC despite planned PBB isolation.
- A foreign tenant EVI imports every received EVPN route without filtering.
- IPv4 IGMP signaling is used expecting IPv6 MLD state to appear.
Explanation
Correct Answer
D:The suspected defect directly frustrates MLD IPv6 membership: IPv4 IGMP signaling is used expecting IPv6 MLD state to appear. Correcting it should allow verification that IPv6 group membership state is present and traffic is forwarded to the receiver.
Incorrect Answers
A:This defect belongs to IGMPv3 inclusion filtering, where the affected outcome is to request multicast only from one specified source at the IPv4 receiver edge. It is not the direct failure mode identified for the MLD IPv6 membership design in this case: IPv4 IGMP signaling is used expecting IPv6 MLD state to appear.
B:This defect belongs to 802.1ah provider backbone bridging, where the affected outcome is to reduce provider core visibility into customer MAC addresses for a large Ethernet service. It is not the direct failure mode identified for the MLD IPv6 membership design in this case: IPv4 IGMP signaling is used expecting IPv6 MLD state to appear.
C:This defect belongs to EVPN route target matching, where the affected outcome is to restrict the import of BGP EVPN routes to the correct tenant service. It is not the direct failure mode identified for the MLD IPv6 membership design in this case: IPv4 IGMP signaling is used expecting IPv6 MLD state to appear.
Question 825
After Bluebird Infrastructure deploys MLD IPv6 membership to enable an IPv6 receiver to join multicast groups on the first-hop router, the primary acceptance check passes (IPv6 group membership state is present and traffic is forwarded to the receiver). What remaining operational risk should still be part of the design review?
- MLD querier and PIMv6 configuration must both be consistent.
- Application and switch support for IGMPv3 is required.
- Edge encapsulation points and service ID mapping require consistent configuration.
- Incorrect route targets can leak connectivity between customer services.
Explanation
Correct Answer
A:The relevant boundary of MLD IPv6 membership is that MLD querier and PIMv6 configuration must both be consistent. Passing the acceptance test does not eliminate this residual operational risk.
Incorrect Answers
B: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 MLD IPv6 membership approach, the relevant caution is instead that MLD querier and PIMv6 configuration must both be consistent.
C:This concern applies to 802.1ah provider backbone bridging in a different scenario where operators need to reduce provider core visibility into customer MAC addresses for a large Ethernet service. For the deployed MLD IPv6 membership approach, the relevant caution is instead that MLD querier and PIMv6 configuration must both be consistent.
D:This concern applies to EVPN route target matching in a different scenario where operators need to restrict the import of BGP EVPN routes to the correct tenant service. For the deployed MLD IPv6 membership approach, the relevant caution is instead that MLD querier and PIMv6 configuration must both be consistent.
Question 826
Horizon Exchange must restore a receiver group whose stream is arriving on an unexpected interface. The operator is comparing several service-provider methods. Which design or control directly addresses that stated requirement?
- PIM-SSM source-specific join
- multicast RPF route failure
- G.8032 Ethernet ring protection
- 802.1ah provider backbone bridging
Explanation
Correct Answer
B:multicast RPF route failure matches this requirement: the team should correct the unicast or multicast RPF path toward the source or rendezvous point. A relevant outcome would be that the incoming interface matches RPF expectations and unwanted drops cease.
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 restore a receiver group whose stream is arriving on an unexpected interface.
C:G.8032 Ethernet ring protection instead addresses a different condition: protect a Carrier Ethernet ring from forwarding loops during normal operation. It would instead require you to configure Ethernet ring protection with its ring protection link behavior, not the stated goal to restore a receiver group whose stream is arriving on an unexpected interface.
D:802.1ah provider backbone bridging instead addresses a different condition: reduce provider core visibility into customer MAC addresses for a large Ethernet service. It would instead require you to apply PBB service encapsulation with backbone MAC and service identifiers where supported, not the stated goal to restore a receiver group whose stream is arriving on an unexpected interface.
Question 827
At Cedar Wireless, the engineering change is approved for multicast RPF route failure. The specific goal is to restore a receiver group whose stream is arriving on an unexpected interface. Which implementation step belongs in this change plan?
- Use SSM with source-aware membership such as IGMPv3 on supported receivers.
- Configure Ethernet ring protection with its ring protection link behavior.
- Correct the unicast or multicast RPF path toward the source or rendezvous point.
- Apply PBB service encapsulation with backbone MAC and service identifiers where supported.
Explanation
Correct Answer
C:Implementing multicast RPF route failure requires the operator to correct the unicast or multicast RPF path toward the source or rendezvous point. This makes the required goal testable using evidence that the incoming interface matches RPF expectations and unwanted drops cease.
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 multicast RPF route failure operation: correct the unicast or multicast RPF path toward the source or rendezvous point.
B:The proposed step is for G.8032 Ethernet ring protection, whose purpose is to protect a Carrier Ethernet ring from forwarding loops during normal operation. It would not perform the necessary multicast RPF route failure operation: correct the unicast or multicast RPF path toward the source or rendezvous point.
D:The proposed step is for 802.1ah provider backbone bridging, whose purpose is to reduce provider core visibility into customer MAC addresses for a large Ethernet service. It would not perform the necessary multicast RPF route failure operation: correct the unicast or multicast RPF path toward the source or rendezvous point.
Question 828
Willow Regional has deployed multicast RPF route failure to restore a receiver group whose stream is arriving on an unexpected interface. The implementation step was to correct the unicast or multicast RPF path toward the source or rendezvous point. Which observation demonstrates that the requested service is working?
- The forwarding entry matches the requested source and group without RP discovery.
- One designated ring section is blocked in steady state and opens for a failure.
- The core switches backbone encapsulation while customer identities stay at the edge.
- The incoming interface matches RPF expectations and unwanted drops cease.
Explanation
Correct Answer
D:For multicast RPF route failure, successful verification means that the incoming interface matches RPF expectations and unwanted drops cease. That evidence directly tests whether the provider can restore a receiver group whose stream is arriving on an unexpected interface after deployment.
Incorrect Answers
A: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 multicast RPF route failure result: the incoming interface matches RPF expectations and unwanted drops cease.
B:The observation would verify G.8032 Ethernet ring protection under the separate requirement to protect a Carrier Ethernet ring from forwarding loops during normal operation. It does not demonstrate the needed multicast RPF route failure result: the incoming interface matches RPF expectations and unwanted drops cease.
C:The observation would verify 802.1ah provider backbone bridging under the separate requirement to reduce provider core visibility into customer MAC addresses for a large Ethernet service. It does not demonstrate the needed multicast RPF route failure result: the incoming interface matches RPF expectations and unwanted drops cease.
Question 829
While troubleshooting multicast RPF route failure at Atlas Backbone, the intended acceptance outcome is still missing: the incoming interface matches RPF expectations and unwanted drops cease. Which fault condition should be investigated first for this particular design?
- IGMP membership is repeatedly refreshed while upstream RPF still fails.
- An any-source IGMPv2 membership is used expecting source-specific filtering.
- All ring links forward at once and create an Ethernet broadcast loop.
- The provider core learns every subscriber MAC despite planned PBB isolation.
Explanation
Correct Answer
A:The suspected defect directly frustrates multicast RPF route failure: IGMP membership is repeatedly refreshed while upstream RPF still fails. Correcting it should allow verification that the incoming interface matches RPF expectations and unwanted drops cease.
Incorrect Answers
B: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 multicast RPF route failure design in this case: IGMP membership is repeatedly refreshed while upstream RPF still fails.
C:This defect belongs to G.8032 Ethernet ring protection, where the affected outcome is to protect a Carrier Ethernet ring from forwarding loops during normal operation. It is not the direct failure mode identified for the multicast RPF route failure design in this case: IGMP membership is repeatedly refreshed while upstream RPF still fails.
D:This defect belongs to 802.1ah provider backbone bridging, where the affected outcome is to reduce provider core visibility into customer MAC addresses for a large Ethernet service. It is not the direct failure mode identified for the multicast RPF route failure design in this case: IGMP membership is repeatedly refreshed while upstream RPF still fails.
Question 830
After Starlight IP Services deploys multicast RPF route failure to restore a receiver group whose stream is arriving on an unexpected interface, the primary acceptance check passes (the incoming interface matches RPF expectations and unwanted drops cease). What remaining operational risk should still be part of the design review?
- The receiver must know and signal the intended multicast source.
- Asymmetric routing requires accurate multicast RPF design.
- Ring protection timers determine switchover and transient disruption.
- Edge encapsulation points and service ID mapping require consistent configuration.
Explanation
Correct Answer
B:The relevant boundary of multicast RPF route failure is that asymmetric routing requires accurate multicast RPF design. 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 multicast RPF route failure approach, the relevant caution is instead that asymmetric routing requires accurate multicast RPF design.
C:This concern applies to G.8032 Ethernet ring protection in a different scenario where operators need to protect a Carrier Ethernet ring from forwarding loops during normal operation. For the deployed multicast RPF route failure approach, the relevant caution is instead that asymmetric routing requires accurate multicast RPF design.
D:This concern applies to 802.1ah provider backbone bridging in a different scenario where operators need to reduce provider core visibility into customer MAC addresses for a large Ethernet service. For the deployed multicast RPF route failure approach, the relevant caution is instead that asymmetric routing requires accurate multicast RPF design.
Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) (350-501) Practice Tests