Nokia Segment Routing v1.0
Question 1
OSPF is being used for segment routing with traffic-engineering (SR-TE). The traffic-engineering option has been set to “sr-te false”. Which of the following statements is TRUE?
- A. The TE information will be advertised for all the OSPF links that have MPLS enabled.
- B. The TE information will only be advertised using application-specific sub-TLVs.
- C. The TE information will only be advertised for the OSPF links that have both MPLS and RSVP enabled.
- D. The TE information will only be advertised using extended-link opaque LSAs.
Answer : B
Question 2
Examine the exhibit.
An LSP is being configured to start at R1 and end at R6 using local-CSPF. The LSP has the following constraints. Include admin-group GREEN, use the TE metric and hop-limit 3. What routers will be included in the LSP path?
- A. R1, R2, R4, R6
- B. R1, R5, R6
- C. R1, R3, R5, R6
- D. R1, R6
Answer : C
Question 3
Examine the exhibit.
Based upon the configuration, which routers will the LSP go through?
- A. R1, R3, R2, R5, R4 and R6
- B. R1, R2, R5 and R6
- C. R1, R3, R4 and R6
- D. R1, R2, R4 and R6
Answer : B
Question 4
Which of the following statements about path definitions is FALSE?
- A. Once a path is associated with an LSP, it cannot be used by other LSPs.
- B. A loose hop is one that does not have to be directly adjacent to the previous hop in the path list.
- C. The path hops can be defined by either the system or physical interface IP address.
- D. In addition to the hops defined in the path list, the head-end and tail-end routers are implicitly added.
Answer : C
Question 5
Which of the following is an advantage of enabling label stack reduction for a CSPF-calculated path, as compared to using plain CSPF?
- A. The number of hops included in the end-to-end path is reduced.
- B. The path calculation can be delegated to an external path computation element (PCE).
- C. There is a larger list of traffic-engineering constraint types that can be imposed on the LSP path.
- D. The routers in the calculated path can take advantage of ECMP to better distribute the traffic load.
Answer : C
Question 6
Which of the following statements about the operation of seamless-BFD is FALSE?
- A. Seamless-BFD responses are sent back using the LSP label stack.
- B. To be able to respond to seamless-BFD messages, a router must be configured as a reflector.
- C. A seamless-BFD template needs to be configured on the head-end of the LSP.
- D. The routing protocol (OSPF or IS-IS) is used to carry the reflector discriminator information.
Answer : C
Question 7
Which of the following statements about primary and secondary SR-TE LSP paths is FALSE?
- A. Only one LSP path forwards the traffic at any time.
- B. Up to three paths can be configured for a given SR-TE LSP.
- C. The primary path is always preferred over a secondary path.
- D. Preference values can be configured for non-standby secondary paths.
Answer : C
Question 8
An SR-TE LSP with a path definition that includes router R4 as a loose hop and for which Seamless-BFD has been enabled is following the path shown in the exhibit. What happens after router R4 fails if the routers along the path follow the default behavior?
- A. The head end will periodically try to calculate a new path at a rate defined by the retry timer.
- B. The head end will periodically try to calculate a new path at a rate defined by the resignal timer.
- C. The head end will continue forwarding traffic to the current next-hop indefinitely, which will be discarded at the point of failure.
- D. The head end will continue forwarding traffic to the current next-hop indefinitely, and R2 will redirect the traffic to R3 after IGP reconvergence.
Answer : C
Question 9
Which of the following statements about the Path Computation Element (PCE) is FALSE?
- A. The PCE can obtain topology and traffic-engineering information from the network using either a link-state IGP or BGP-LS.
- B. A stateful PCE proactively monitors all the existing LSPs and triggers the necessary repairs and re-optimizations.
- C. A stateless PCE can calculate cross-area traffic-engineering-constrained LSP paths.
- D. A stateful PCE can allow LSPs to reserve bandwidth.
Answer : C
Question 10
Based on the exhibit, which of the following is a viable option for the Path Computation Element (PCE) to obtain all the necessary topology and traffic-engineering information from the network, so that it can calculate LSP paths on behalf of the PE routers?
- A. Establishing an IGP adjacency with router R2
- B. Establishing IGP adjacencies with routers R1 and R2
- C. Establishing a BGP session using the BGP-LS address family with router R3
- D. Establishing BGP sessions using the BGP-LS address family with routers R3 and R4
Answer : D
Question 11
Which of the following types of information is considered by a stateless PCE when it processes a new LSP path calculation request?
- A. The IGP link-state database
- B. The traffic-engineering database
- C. The operational state of existing LSP paths
- D. The amount of bandwidth reserved for each of the existing LSP paths
Answer : B
Question 12
Which of the following is NOT an advantage of using a PCE for the computation of TE-constrained LSP paths, as compared to using CSPF locally on the PE router?
- A. The ability to create cross-area TE-constrained LSP paths
- B. The ability to create LSP paths with bandwidth reservation
- C. The ability to create LSPs with primary and secondary paths
- D. The ability to ensure that some LSP paths are disjoint
Answer : D
Question 13
In the context of a network that includes a Path Computation Element (PCE), what is a PCC-initiated LSP?
- A. An LSP that needs to be explicitly configured on the head-end router.
- B. An LSP for which the initial path is calculated by the head-end router.
- C. An LSP for which the path repairs and re-optimizations must be triggered by the head-end router.
- D. An LSP whose existence and state are reported to the PCE.
Answer : D
Question 14
Which of the following statements about segment routing fast re-route is FALSE?
- A. Fast re-route is a temporary fix that becomes active for a short period of time after a local network failure.
- B. Fast re-route typically protects the active segment of a tunnel, but under certain conditions it can protect an end-to-end multi-segment tunnel instead.
- C. On a Nokia 7750 SR, R-LFA and TI-LFA can be enabled independently of each other.
- D. The parameter “max-sr-frr-labels” limits the number of labels that R-LFA can add to the data packet encapsulation.
Answer : C
Question 15
The exhibit presents packets being transmitted inside an LSP's multi-segment primary path going from router R1 to router R8. The LSP also has a standby secondary path, and Seamless-BFD has been enabled on the primary path. The link between routers R1 and R2 fails, and fast re-route (FRR) is triggered. As a result, router R1 forwards the packets to router R3 and adds the proper FRR encapsulation to reach which router?
- A. To reach router R2, which is the LSP's intended next-hop.
- B. To reach router R5, which is the shortest way to go back to the original path.
- C. To reach router R4, which is the tail-end of the active segment.
- D. To reach router R8, which is the tail-end of the LSP.
Answer : B