642-887 Latest Exam (Aug 2018)

[Free] 2018(Aug) Ensurepass Cisco 642-887 Dumps with VCE and PDF 21-30

September 14, 2018

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2018 Aug Cisco Official New Released 642-887
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Implementing Cisco Service Provider Next-Generation Core Network Services

Question No: 21

Which item is not available to be used for QoS classification in Cisco IOS XR?

  1. MAC SA

  2. protocol

  3. inner EXP

  4. discard-class

  5. QoS-group

  6. VLAN

Answer: C

Question No: 22

A network engineer must design a core network routing domain that supports Cisco MPLS TE. Which two interior gateway protocols represent viable solutions? (Choose two.)

  1. Routing Information Protocol version 2

  2. Open Shortest Path First

  3. Enhanced Interior Gateway Routing Protocol

  4. Intermediate-System to Intermediate-System

  5. Border Gateway Protocol

Answer: B,D

Question No: 23

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Refer to the exhibit. XR2 needs to have LDP configured with PE1. Which configuration achieves this goal?

  1. interface giga 0/0 Mpls ip



  2. router ospf 1

    mpls ldp auto config area 0 exit


  3. router ospf 1

    area 0 mpls ldp auto config exit


  4. interface giga 0/1 mpls ldp

exit commit

Answer: C

Question No: 24


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From the PE8 router, how many total prefixes for have an incoming local label assigned (including the imp-null)?

  1. 45

  2. 21

  3. 66

  4. 22

Answer: B

Explanation: On PE8 issue: show mpls ip binding summary and look at quot;assigned in labelsquot;. That value is the correct answer NOT quot;learned out labelquot;.

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Question No: 25

Which three statements are correct regarding ping mpls command operations? (Choose three.)

  1. MPLS OAM has to be enabled on the router using the mpls oam command.

  2. They use a 127/8 address as the destination address in the MPLS echo request packet.

  3. They use ICMP echo request and ICMP echo reply packets.

  4. They are used to test for a broken LSP.

  5. If there is a broken LSP, instead of using label switching, the packet can still be forwarded based on the destination IP address in the mpls ping echo request packet.

Answer: A,B,D Explanation:

How MPLS Ping works?

MPLS Ping doesn’t rely on ICMP echo messages. Instead it uses UDP protocol with both source and destination port as 3503 and relies on MPLS Echo request and MPLS Echo reply.

When MPLS ping is triggered from any MPLS router, it will generate UDP segment with source/destination port as 3503. The source address will be selected as usual while the destination address will be The IP TTL will be set to 1.

Below is a sample IP format when MPLS Ping is originated from R5 to,

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Now the originating LSR will look into the LFIB and populate the label header with respective labels to reach the FEC, in our case

R4 on receiving the MPLS packet will be able to send to the actual destination only if the LSP is end to end. If the LSP is broken between R4 and R6, R4 will look into the destination IP address which will be and won’t be able to perform IP forwarding. As per RFC 1812, a router should not forward any packet that has destination address of

Question No: 26 DRAG DROP

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Question No: 27

A DSCP value of 41 in decimal corresponds to which IP precedence value?

  1. 3 – Flash

  2. 4 – Flash Override

  3. 5 – Critical

  4. 6 – Internet Control

  5. 7 – Network Control

Answer: C Explanation:

= INT(41/8)

The AF behavior group defines four separate AF classes with Class 4 having the highest priority. Within each class, packets are given a drop precedence (high, medium or low). The combination of classes and drop precedence yields twelve separate DSCP encodings from AF11 through AF43 (see table)

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Question No: 28

Which two of the following statements are correct regarding LSPs? (Choose two.)

  1. An LSP is created for every routing protocol entry.

  2. Each LSP is bidirectional, that is, packets traveling in the opposite direction use the same LSP.

  3. An IGP is used to populate routing tables in all routers in an MPLS domain.

  4. LDP is used to propagate labels and build LSPs.

  5. The FIB is used to forward MPLS-labeled packets down an LSP.

Answer: C,D

Question No: 29

A network engineer must make a reservable maximum bandwidth of 75 Mbps on a Cisco ASR 9000 series router. Which configuration satisfies this requirement in Cisco IOS XR?

A. 2802_FY14Q4_CORE_Q33_o1 B. 2813_FY14Q4_CORE_Q33_o2 C. 2824_FY14Q4_CORE_Q33_o3 D. 2835_FY14Q4_CORE_Q33_o4

Answer: C

Question No: 30

Which three network services can be implemented using MPLS within the service provider IP NGN core? (Choose three.)

  1. Layer 2 VPNs

  2. Layer 3 VPNs

  3. traffic engineering

  4. IntServ traffic engineering tunnels

  5. encrypted LSPs

Answer: A,B,C

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