Cisco 642-887 Online Practice Questions and Exam Preparation

Cisco 642-887 Online Questions & Answers

• Question 21:

  Layer 2 VPN services that are offered by traditional service providers using a SONET/SDH backbone can be implemented by service providers using an IP/MPLS backbone with which MPLS feature?

  A. LSP stitching
  B. AToM
  C. virtual private WAN services
  D. cell-mode MPLS
  B. AToM

• Question 22:

  Which four pieces of information are stored for each prefix in the LFIB? (Choose four.)

  A. local label
  B. outgoing label
  C. next-hop IP address
  D. outgoing interface
  E. incoming interface
  F. Layer 2 header rewrite information
  A. local label
  B. outgoing label
  C. next-hop IP address
  D. outgoing interface

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  Forwarding Labeled Packets LSR forwards the packet based on: Top Label value of the received packet Corresponding entry in LFIB (LABEL <=> INTERFACE) #show mpls forwarding-table - will show: local label outgoing label prefix (network) outgoing interface next-hop

  

  LSR expects packet to come with "top" label being "Local" (from show mpls forwarding- table).

  If Outgoing label is "Aggregate", then that means that this is a summary route and more specific lookup is performed.

  If LSR cannot find label/interface mapping in LFIB, then it drops the packet. There are several "RESERVED" labels numbered from 0 to 15:

  0 - explicit NULL - is used to preserver QoS info through EXP bits. It copies 'ip prec' or DiffServ.

  1 - Router alert label - forces LSR to software switch the packet. 3 - Implicit NULL - this label is used for "connected" or "summary" routes. This way LSR signals its neighbors to execute "POP label" operation on "connected" routes. It is called

  PHP, Penultimate Hop Popping, and is used to make sure that LSR does not perform 2 lookups (label + ip).

  14 - OEM alert label - is used for monitoring purpose. In Cisco IOS, the default range is 16 through 100,000, but can be expanded by using "mpls label range" command.

• Question 23:

  On the Cisco IOS XR, which MQC configuration is different than on the Cisco IOS and IOS XE?

  A. On the Cisco IOS XR, WRED can only be applied in the output direction.
  B. On the Cisco IOS XR, marking can only be applied in the input direction.
  C. On the Cisco IOS XR, LLQ can be applied in the input or output direction.
  D. On the Cisco IOS XR, LLQ can use up to four priority queues: level 1, level 2, level 3, and level 4.
  C. On the Cisco IOS XR, LLQ can be applied in the input or output direction.

• Question 24:

  Refer to the partial Cisco IOS XR configurations exhibit for Router 1 and Router 2.

  

  There are two routers that are connected back to back over the Gigabit Ethernet link. If the "show mpls ldp neighbor" command output on Router 1 does not show LDP peering with Router 2, what could be the possible root cause of the LDP peering problem?

  A. missing interface under OSPF IGP configuration
  B. hello timers mismatch on Router 1 and Router 2
  C. password for LDP session mismatch on Router 1 and Router 2
  D. MPLS LDP session protection is not configured
  A. missing interface under OSPF IGP configuration

• Question 25:

  What is a primary difference between QoS operations on IOS and IOS XR?

  A. IOS XR features multi-level LLQ
  B. IOS XR automatically polices the LLQ
  C. IOS XR does not support NBAR
  D. IOS XR cannot set FR-DE
  B. IOS XR automatically polices the LLQ

• Question 26:

  Which two network devices are trusted endpoints in a network? (Choose two.)

  A. video endpoint
  B. PC
  C. wireless clients
  D. IP phone
  A. video endpoint
  D. IP phone

• Question 27:

  Refer to the exhibit.

  

  MPLS TE Tunnel 138 has a headend R1 and a tailend R4, and uses path R1-R2-R4 as the primary LSP. The path R1-R2-R3-R4 should be implemented as a backup LSP in case the R2-R4 link fails. To which interface should the appropriate configuration be applied to accomplish this?

  

  A. Option A
  B. Option B
  C. Option C
  D. Option D
  C. Option C

• Question 28:

  Which option shows how a class map is implemented that matches only packets originating from the network 10.0.0.0/8, which are not marked as VoIP on Cisco IOS XE?

  

  A. Option A
  B. Option B
  C. Option C
  D. Option D
  B. Option B

• Question 29:

  How is bandwidth recalculated when utilizing the automatic bandwidth adjustment feature for MPLS TE?

  A. The tunnel's output average is periodically sampled and then the bandwidth is adjusted to the largest sample obtained during the period, or to the configured maximum
  B. The tunnel's output is sampled and then the bandwidth is adjusted by a configured percentage until the configured maximum value is reached
  C. Ping is used to measure congestion and the bandwidth is adjusted by a configured percentage until the maximum value is reached
  D. Ping is used to measure congestion and the bandwidth is adjusted to either the minimum, average, or maximum configured bandwidth value
  A. The tunnel's output average is periodically sampled and then the bandwidth is adjusted to the largest sample obtained during the period, or to the configured maximum

• Question 30:

  Which three mechanisms are used to implement MPLS TE? (Choose three.)

  A. tunnel interface
  B. CSPF
  C. RSVP
  D. LDP
  E. MP-BGP
  A. tunnel interface
  B. CSPF
  C. RSVP

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  Constrained-Based Shortest Path First (CSPF).

  Resource Reservation Protocol - Traffic Engineering is an extension of the resource reservation protocol (RSVP) for traffic engineering.