Cisco 642-887 Online Practice Questions and Exam Preparation

Cisco 642-887 Online Questions & Answers

• Question 71:

  A network operations center requests support to configure a Cisco MPLS TE tunnel on a Cisco IOS XR router. Which command sets a specific bandwidth required to the corresponding Cisco MPLS TE tunnel?

  A. rsvp interface interface-path-id bandwidth bandwidth
  B. interface tunnel-te tunnel_id ! bandwidth bandwidth
  C. interface tunnel-te tunnel_id ! signaled-bandwidth bandwidth
  D. mpls traffic-eng auto-bw collect frequency value !
  C. interface tunnel-te tunnel_id ! signaled-bandwidth bandwidth

• Question 72:

  What is a crucial LDP default operating behavior?

  A. LDP uses the solicited mode by default. An LDP label request is sent to the FIB next hop LSR. When the egress router receives the request, it returns message with all the label-mapping information for the LSP is generated.
  B. LDP establishes a TCP session between the PE routers, thus providing label mapping for the LSP
  C. LDP uses downstream unsolicited mode by default. An LSR advertises label mappings to peers without being asked
  D. LDP uses UDP-confirmed messages to establish sessions between PE ingress and egress routers. The UDP messages encode the label information for each LSP and sub- LSP link
  C. LDP uses downstream unsolicited mode by default. An LSR advertises label mappings to peers without being asked

• Question 73:

  Drag the QoS model on the left to match its correct description on the right

  Select and Place:

  

  

• Question 74:

  When implementing Cisco MPLS TE, the constrained-based path calculations will use which value as the TE cost of each link within the MPLS domain?

  A. By default, it will use the IGP metric, or each link can be assigned a specific value using the admin-weight command.
  B. It can only use the IGP metric as the TE cost.
  C. It will use the interface bandwidth as the TE cost.
  D. Each link must be assigned a TE cost using the metric command.
  A. By default, it will use the IGP metric, or each link can be assigned a specific value using the admin-weight command.

• Question 75:

  LDP session protection uses which one to maintain the LDP session between LDP neighbors?

  A. LDP NSF
  B. LDP NSR
  C. backup-targeted LDP hellos
  D. BFD
  E. LDP-IGP synchronization
  C. backup-targeted LDP hellos

• Question 76:

  Refer to the exhibit. Which configuration error prevents this traffic-shaping policy from working?

  

  A. The WAN interface is starting to drop packets because no queuing mechanism is implemented.
  B. Traffic-shaping policies are applied only in the outbound direction.
  C. The class_A configuration shape peak is used to maximize the serial interface performances.
  D. The service-policy command is applied only on logical or channeled interfaces.
  B. Traffic-shaping policies are applied only in the outbound direction.

• Question 77:

  Which field in the MPLS shim header is used to support different QoS markings?

  A. IP precedence
  B. DSCP
  C. EXP
  D. ToS
  E. S
  F. Label
  C. EXP

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  MPLS EXP Marking The three MPLS EXP (experimental) bits in the shim header of an input or output MPLS packet header may be set or changed by a user configured value

• Question 78:

  Which two factors must you consider when configuring MPLS EXP? (Choose two.)

  A. MPLS EXP marking is supported in the egress direction
  B. A packet that IP ToS classifies at ingress can be reclassified by MPLS EXP at egress
  C. MPLS EXP marking is supported in the ingress direction
  D. MPLS EXP classification for bridged MPLS packets on EVCs is supported
  E. A packet that MPLS classifies at ingress can be reclassified by IP ToS at egress
  C. MPLS EXP marking is supported in the ingress direction
  E. A packet that MPLS classifies at ingress can be reclassified by IP ToS at egress

• Question 79:

  An LDP session is established between two neighbors. Over which protocol and port number do they maintain their adjacency?

  A. TCP 711
  B. UDP 646
  C. UDP 711
  D. TCP 646
  D. TCP 646

• Question 80:

  When implementing MPLS DS-TE on Cisco IOS XR routers, all aggregate Cisco MPLS TE traffic is mapped to which class type by default?

  A. class-type 0 (bandwidth global pool)
  B. class-type 1 (bandwidth subpool)
  C. class-type 2 (bandwidth priority)
  D. class type class-default (bandwidth best-effort)
  A. class-type 0 (bandwidth global pool)

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  Differentiated Services Traffic Engineering MPLS Differentiated Services (Diff-Serv) Aware Traffic Engineering (DS-TE) is an extension of the regular MPLS-TE feature. Regular traffic engineering does not provide bandwidth guarantees to different traffic classes. A single bandwidth constraint is used in regular TE that is shared by all traffic. To support various classes of service (CoS), users can configure multiple bandwidth constraints. These bandwidth constraints can be treated differently based on the requirement for the traffic class using that constraint.

  MPLS diff-serv traffic engineering provides the ability to configure multiple bandwidth constraints on an MPLSenabled interface. Available bandwidths from all configured bandwidth constraints are advertised using IGP.

  TE tunnel is configured with bandwidth value and class-type requirements. Path calculation and admission control take the bandwidth and class-type into consideration. RSVP is used to signal the TE tunnel with bandwidth and class-type requirements.

  Diff-Serv TE can be deployed with either Russian Doll Model (RDM) or Maximum Allocation Model (MAM) for bandwidth calculations.