Question 530
After Harbor Metro deploys CBTS tunnel service assignment to steer traffic classes over traffic-engineered tunnels according to service treatment, the primary acceptance check passes (premium and best-effort classes follow their intended TE tunnels). What remaining operational risk should still be part of the design review?
- Preemption can interrupt displaced services and requires policy controls.
- Fallback behavior matters if a class-specific tunnel becomes unavailable.
- Loss of PCE connectivity requires planned fallback behavior.
- Synchronization failure handling should not permanently isolate healthy IP service.
Explanation
Correct Answer
B:The relevant boundary of CBTS tunnel service assignment is that fallback behavior matters if a class-specific tunnel becomes unavailable. Passing the acceptance test does not eliminate this residual operational risk.
Incorrect Answers
A:This concern applies to MPLS-TE preemption priority in a different scenario where operators need to allow higher-priority reservation requests to displace lower-priority capacity commitments. For the deployed CBTS tunnel service assignment approach, the relevant caution is instead that fallback behavior matters if a class-specific tunnel becomes unavailable.
C:This concern applies to PCE PCC path delegation in a different scenario where operators need to allow a centralized PCE to update a delegated SR-TE candidate path on a headend. For the deployed CBTS tunnel service assignment approach, the relevant caution is instead that fallback behavior matters if a class-specific tunnel becomes unavailable.
D:This concern applies to IGP LDP synchronization in a different scenario where operators need to avoid forwarding traffic onto a link before necessary MPLS labels are usable. For the deployed CBTS tunnel service assignment approach, the relevant caution is instead that fallback behavior matters if a class-specific tunnel becomes unavailable.
Question 531
Summit Service Provider must delegate constrained SR-TE or MPLS-TE path computation to a path computation entity. The operator is comparing several service-provider methods. Which design or control directly addresses that stated requirement?
- MPLS-TE preemption priority
- SR static versus dynamic path choice
- PCE constrained path computation
- SRv6 locator aggregation
Explanation
Correct Answer
C:PCE constrained path computation matches this requirement: the team should use a PCE-PCC architecture with agreed objectives and topology visibility. A relevant outcome would be that the PCC receives a viable path matching the constraints and programs it.
Incorrect Answers
A:MPLS-TE preemption priority instead addresses a different condition: allow higher-priority reservation requests to displace lower-priority capacity commitments. It would instead require you to configure setup and hold priorities consistently with the provider TE policy, not the stated goal to delegate constrained SR-TE or MPLS-TE path computation to a path computation entity.
B:SR static versus dynamic path choice instead addresses a different condition: choose a repeatable explicit path when an operator needs fixed audited waypoints. It would instead require you to configure an explicit SR segment list candidate rather than only dynamic SPF computation, not the stated goal to delegate constrained SR-TE or MPLS-TE path computation to a path computation entity.
D:SRv6 locator aggregation instead addresses a different condition: allocate routable prefixes to identify SRv6-capable nodes and behaviors. It would instead require you to configure a valid SRv6 locator prefix and corresponding IGP advertisement, not the stated goal to delegate constrained SR-TE or MPLS-TE path computation to a path computation entity.
Question 532
At Ridgeway Networks, the engineering change is approved for PCE constrained path computation. The specific goal is to delegate constrained SR-TE or MPLS-TE path computation to a path computation entity. Which implementation step belongs in this change plan?
- Configure setup and hold priorities consistently with the provider TE policy.
- Configure an explicit SR segment list candidate rather than only dynamic SPF computation.
- Configure a valid SRv6 locator prefix and corresponding IGP advertisement.
- Use a PCE-PCC architecture with agreed objectives and topology visibility.
Explanation
Correct Answer
D:Implementing PCE constrained path computation requires the operator to use a PCE-PCC architecture with agreed objectives and topology visibility. This makes the required goal testable using evidence that the PCC receives a viable path matching the constraints and programs it.
Incorrect Answers
A:The proposed step is for MPLS-TE preemption priority, whose purpose is to allow higher-priority reservation requests to displace lower-priority capacity commitments. It would not perform the necessary PCE constrained path computation operation: use a PCE-PCC architecture with agreed objectives and topology visibility.
B:The proposed step is for SR static versus dynamic path choice, whose purpose is to choose a repeatable explicit path when an operator needs fixed audited waypoints. It would not perform the necessary PCE constrained path computation operation: use a PCE-PCC architecture with agreed objectives and topology visibility.
C:The proposed step is for SRv6 locator aggregation, whose purpose is to allocate routable prefixes to identify SRv6-capable nodes and behaviors. It would not perform the necessary PCE constrained path computation operation: use a PCE-PCC architecture with agreed objectives and topology visibility.
Question 533
Lakeside Transport has deployed PCE constrained path computation to delegate constrained SR-TE or MPLS-TE path computation to a path computation entity. The implementation step was to use a PCE-PCC architecture with agreed objectives and topology visibility. Which observation demonstrates that the requested service is working?
- The PCC receives a viable path matching the constraints and programs it.
- Admission selects eligible reservations and preemption obeys intended priorities.
- Policy forwarding traverses the recorded waypoint order under healthy conditions.
- The locator is reachable and its local SID behaviors resolve on the endpoint.
Explanation
Correct Answer
A:For PCE constrained path computation, successful verification means that the PCC receives a viable path matching the constraints and programs it. That evidence directly tests whether the provider can delegate constrained SR-TE or MPLS-TE path computation to a path computation entity after deployment.
Incorrect Answers
B:The observation would verify MPLS-TE preemption priority under the separate requirement to allow higher-priority reservation requests to displace lower-priority capacity commitments. It does not demonstrate the needed PCE constrained path computation result: the PCC receives a viable path matching the constraints and programs it.
C:The observation would verify SR static versus dynamic path choice under the separate requirement to choose a repeatable explicit path when an operator needs fixed audited waypoints. It does not demonstrate the needed PCE constrained path computation result: the PCC receives a viable path matching the constraints and programs it.
D:The observation would verify SRv6 locator aggregation under the separate requirement to allocate routable prefixes to identify SRv6-capable nodes and behaviors. It does not demonstrate the needed PCE constrained path computation result: the PCC receives a viable path matching the constraints and programs it.
Question 534
While troubleshooting PCE constrained path computation at Coastal Communications, the intended acceptance outcome is still missing: the PCC receives a viable path matching the constraints and programs it. Which fault condition should be investigated first for this particular design?
- Low-priority LSPs consume all reservable capacity while urgent LSPs cannot signal.
- A path is selected by local shortest path ignoring the stated constraint.
- An automatically recomputed dynamic path violates the mandated deterministic route.
- A SID is created without a routed locator leading traffic to that node.
Explanation
Correct Answer
B:The suspected defect directly frustrates PCE constrained path computation: a path is selected by local shortest path ignoring the stated constraint. Correcting it should allow verification that the PCC receives a viable path matching the constraints and programs it.
Incorrect Answers
A:This defect belongs to MPLS-TE preemption priority, where the affected outcome is to allow higher-priority reservation requests to displace lower-priority capacity commitments. It is not the direct failure mode identified for the PCE constrained path computation design in this case: a path is selected by local shortest path ignoring the stated constraint.
C:This defect belongs to SR static versus dynamic path choice, where the affected outcome is to choose a repeatable explicit path when an operator needs fixed audited waypoints. It is not the direct failure mode identified for the PCE constrained path computation design in this case: a path is selected by local shortest path ignoring the stated constraint.
D:This defect belongs to SRv6 locator aggregation, where the affected outcome is to allocate routable prefixes to identify SRv6-capable nodes and behaviors. It is not the direct failure mode identified for the PCE constrained path computation design in this case: a path is selected by local shortest path ignoring the stated constraint.
Question 535
After Bluebird Infrastructure deploys PCE constrained path computation to delegate constrained SR-TE or MPLS-TE path computation to a path computation entity, the primary acceptance check passes (the PCC receives a viable path matching the constraints and programs it). What remaining operational risk should still be part of the design review?
- Preemption can interrupt displaced services and requires policy controls.
- Explicit segment lists need operational update when topology changes.
- PCE availability and stale topology information can limit path validity.
- Locator planning must avoid overlap and comply with forwarding prefix constraints.
Explanation
Correct Answer
C:The relevant boundary of PCE constrained path computation is that PCE availability and stale topology information can limit path validity. Passing the acceptance test does not eliminate this residual operational risk.
Incorrect Answers
A:This concern applies to MPLS-TE preemption priority in a different scenario where operators need to allow higher-priority reservation requests to displace lower-priority capacity commitments. For the deployed PCE constrained path computation approach, the relevant caution is instead that PCE availability and stale topology information can limit path validity.
B:This concern applies to SR static versus dynamic path choice in a different scenario where operators need to choose a repeatable explicit path when an operator needs fixed audited waypoints. For the deployed PCE constrained path computation approach, the relevant caution is instead that PCE availability and stale topology information can limit path validity.
D:This concern applies to SRv6 locator aggregation in a different scenario where operators need to allocate routable prefixes to identify SRv6-capable nodes and behaviors. For the deployed PCE constrained path computation approach, the relevant caution is instead that PCE availability and stale topology information can limit path validity.
Question 536
Horizon Exchange must allow higher-priority reservation requests to displace lower-priority capacity commitments. The operator is comparing several service-provider methods. Which design or control directly addresses that stated requirement?
- RSVP TE explicit path
- LDP address family transport
- LDP label binding verification
- MPLS-TE preemption priority
Explanation
Correct Answer
D:MPLS-TE preemption priority matches this requirement: the team should configure setup and hold priorities consistently with the provider TE policy. A relevant outcome would be that admission selects eligible reservations and preemption obeys intended priorities.
Incorrect Answers
A:RSVP TE explicit path instead addresses a different condition: steer an MPLS TE tunnel over selected intermediate nodes rather than only IGP shortest path. It would instead require you to configure an RSVP-TE tunnel with a suitable explicit-route object, not the stated goal to allow higher-priority reservation requests to displace lower-priority capacity commitments.
B:LDP address family transport instead addresses a different condition: carry the intended labeled IPv4 transport prefixes consistently across a provider core. It would instead require you to enable the supported address-family LDP capability on participating routers, not the stated goal to allow higher-priority reservation requests to displace lower-priority capacity commitments.
C:LDP label binding verification instead addresses a different condition: check the label binding for a specific IGP destination before enabling a VPN. It would instead require you to inspect local and remote LDP bindings and installed labeled forwarding entries, not the stated goal to allow higher-priority reservation requests to displace lower-priority capacity commitments.
Question 537
At Cedar Wireless, the engineering change is approved for MPLS-TE preemption priority. The specific goal is to allow higher-priority reservation requests to displace lower-priority capacity commitments. Which implementation step belongs in this change plan?
- Configure setup and hold priorities consistently with the provider TE policy.
- Configure an RSVP-TE tunnel with a suitable explicit-route object.
- Enable the supported address-family LDP capability on participating routers.
- Inspect local and remote LDP bindings and installed labeled forwarding entries.
Explanation
Correct Answer
A:Implementing MPLS-TE preemption priority requires the operator to configure setup and hold priorities consistently with the provider TE policy. This makes the required goal testable using evidence that admission selects eligible reservations and preemption obeys intended priorities.
Incorrect Answers
B:The proposed step is for RSVP TE explicit path, whose purpose is to steer an MPLS TE tunnel over selected intermediate nodes rather than only IGP shortest path. It would not perform the necessary MPLS-TE preemption priority operation: configure setup and hold priorities consistently with the provider TE policy.
C:The proposed step is for LDP address family transport, whose purpose is to carry the intended labeled IPv4 transport prefixes consistently across a provider core. It would not perform the necessary MPLS-TE preemption priority operation: configure setup and hold priorities consistently with the provider TE policy.
D:The proposed step is for LDP label binding verification, whose purpose is to check the label binding for a specific IGP destination before enabling a VPN. It would not perform the necessary MPLS-TE preemption priority operation: configure setup and hold priorities consistently with the provider TE policy.
Question 538
Willow Regional has deployed MPLS-TE preemption priority to allow higher-priority reservation requests to displace lower-priority capacity commitments. The implementation step was to configure setup and hold priorities consistently with the provider TE policy. Which observation demonstrates that the requested service is working?
- The established tunnel follows listed hops and reserves the requested resources.
- Admission selects eligible reservations and preemption obeys intended priorities.
- LDP neighbors and FEC bindings appear for the selected address family.
- The expected FEC maps to valid incoming and outgoing label operations.
Explanation
Correct Answer
B:For MPLS-TE preemption priority, successful verification means that admission selects eligible reservations and preemption obeys intended priorities. That evidence directly tests whether the provider can allow higher-priority reservation requests to displace lower-priority capacity commitments after deployment.
Incorrect Answers
A:The observation would verify RSVP TE explicit path under the separate requirement to steer an MPLS TE tunnel over selected intermediate nodes rather than only IGP shortest path. It does not demonstrate the needed MPLS-TE preemption priority result: admission selects eligible reservations and preemption obeys intended priorities.
C:The observation would verify LDP address family transport under the separate requirement to carry the intended labeled IPv4 transport prefixes consistently across a provider core. It does not demonstrate the needed MPLS-TE preemption priority result: admission selects eligible reservations and preemption obeys intended priorities.
D:The observation would verify LDP label binding verification under the separate requirement to check the label binding for a specific IGP destination before enabling a VPN. It does not demonstrate the needed MPLS-TE preemption priority result: admission selects eligible reservations and preemption obeys intended priorities.
Question 539
While troubleshooting MPLS-TE preemption priority at Atlas Backbone, the intended acceptance outcome is still missing: admission selects eligible reservations and preemption obeys intended priorities. Which fault condition should be investigated first for this particular design?
- An ordinary LDP LSP follows IGP SPF instead of the required explicit path.
- An IPv6-only label session is expected to install IPv4 FEC bindings without support.
- Low-priority LSPs consume all reservable capacity while urgent LSPs cannot signal.
- An LDP neighbor is up but no label binding exists for the target FEC.
Explanation
Correct Answer
C:The suspected defect directly frustrates MPLS-TE preemption priority: low-priority LSPs consume all reservable capacity while urgent LSPs cannot signal. Correcting it should allow verification that admission selects eligible reservations and preemption obeys intended priorities.
Incorrect Answers
A:This defect belongs to RSVP TE explicit path, where the affected outcome is to steer an MPLS TE tunnel over selected intermediate nodes rather than only IGP shortest path. It is not the direct failure mode identified for the MPLS-TE preemption priority design in this case: low-priority LSPs consume all reservable capacity while urgent LSPs cannot signal.
B:This defect belongs to LDP address family transport, where the affected outcome is to carry the intended labeled IPv4 transport prefixes consistently across a provider core. It is not the direct failure mode identified for the MPLS-TE preemption priority design in this case: low-priority LSPs consume all reservable capacity while urgent LSPs cannot signal.
D:This defect belongs to LDP label binding verification, where the affected outcome is to check the label binding for a specific IGP destination before enabling a VPN. It is not the direct failure mode identified for the MPLS-TE preemption priority design in this case: low-priority LSPs consume all reservable capacity while urgent LSPs cannot signal.
Question 540
After Starlight IP Services deploys MPLS-TE preemption priority to allow higher-priority reservation requests to displace lower-priority capacity commitments, the primary acceptance check passes (admission selects eligible reservations and preemption obeys intended priorities). What remaining operational risk should still be part of the design review?
- Strict hop constraints fail if an intermediate node or link becomes unavailable.
- Dual-stack label operation depends on platform feature compatibility.
- Missing labels can produce selective packet loss despite healthy routing.
- Preemption can interrupt displaced services and requires policy controls.
Explanation
Correct Answer
D:The relevant boundary of MPLS-TE preemption priority is that preemption can interrupt displaced services and requires policy controls. Passing the acceptance test does not eliminate this residual operational risk.
Incorrect Answers
A:This concern applies to RSVP TE explicit path in a different scenario where operators need to steer an MPLS TE tunnel over selected intermediate nodes rather than only IGP shortest path. For the deployed MPLS-TE preemption priority approach, the relevant caution is instead that preemption can interrupt displaced services and requires policy controls.
B:This concern applies to LDP address family transport in a different scenario where operators need to carry the intended labeled IPv4 transport prefixes consistently across a provider core. For the deployed MPLS-TE preemption priority approach, the relevant caution is instead that preemption can interrupt displaced services and requires policy controls.
C:This concern applies to LDP label binding verification in a different scenario where operators need to check the label binding for a specific IGP destination before enabling a VPN. For the deployed MPLS-TE preemption priority approach, the relevant caution is instead that preemption can interrupt displaced services and requires policy controls.
Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) (350-501) Practice Tests