Cisco 642-887 Torrent 2021

NEW QUESTION 1
DRAG DROP

• A. Mastered
• B. Not Mastered

Answer: A

Explanation:
Applies the QOS policy to interface—service policy
Defines the PHB qos action for each of the different traffic classes—policy map Defines the making parameters for classifying packets into service classes—class-map
Applies the QOS policy to interface--service policy
Defines the PHB qos action for each of the different traffic classes--policy map Defines the making parameters for classifying packets into service classes--class-map

NEW QUESTION 2
Referring to the show output exhibit, which statement is correct?

• A. The P1 router is receiving label information for the 10.0.2.1/32 prefix from two LDP peers.
• B. The P1 router is receiving label information for the 10.7.1.1/32 prefix from two LDP peers.
• C. The P1 router is using the IMP-NULL local label for the 10.7.1.1/32 prefix because 10.7.1.1/32 is the loopback interface IP address on the P1 router.
• D. The P1 router will perform PHP for the 10.7.1.1/32 and 10.7.10.1./32 prefixes.

Answer: B

NEW QUESTION 3
On Cisco routers, which QoS marker is only locally significant?

• A. DSCP
• B. MPLS EXP
• C. IP precedence
• D. QoS group
• E. discard eligible (DE)

Answer: D

NEW QUESTION 4
Which two values are class-selector DSCP values? (Choose two.)

• A. 001001
• B. 000111
• C. 111000
• D. 100000
• E. 000001

Answer: CD

NEW QUESTION 5
Which Cisco IOS XR command should be used to identify if MPLS TE FRR is enabled?

• A. show mpls traffic-eng tunnel <tunnel#>
• B. show mpls frr
• C. show mpls traffic-eng protection
• D. show mpls protection
• E. show mpls fast-reroute

Answer: A

Explanation:
The MPLS Traffic Engineering (TE)—Fast Reroute (FRR) Link and Node Protection feature provides link protection (backup tunnels that bypass only a single link of the label-switched path (LSP)), node protection (backup tunnels that bypass next-hop nodes along LSPs), and the following FRR features:
•Backup tunnel support
•Backup bandwidth protection
•Resource Reservation Protocol (RSVP) Hellos
Prerequisites for MPLS Traffic Engineering (TE)—Fast Reroute (FRR) Link and Node Protection
Your network must support the following Cisco IOS features:
•IP Cisco Express Forwarding
•Multiprotocol Label Switching (MPLS)
Your network must support at least one of the following protocols:
•Intermediate System-to-Intermediate System (IS-IS)
•Open Shortest Path First (OSPF)
Before configuring FRR link and node protection, it is assumed that you have done the following tasks but you do not have to already have configured MPLS TE tunnels:
•Enabled MPLS TE on all relevant routers and interfaces
•Configured MPLS TE tunnels

NEW QUESTION 6
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. rsvpinterface 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-engauto-bw collect frequency value!

Answer: C

NEW QUESTION 7
Which statement is correct regarding the default MPLS TTL behavior?

• A. When an ingress edge LSR receives an IP packet, it will decrement the IP TTL field by 1; then it will set the MPLS Label TTL field to 255.
• B. When an ingress edge LSR receives an IP packet, it will decrement the IP TTL field by 1; then it will copy the decremented IP TTL field into the MPLS Label TTL field.
• C. When an ingress edge LSR receives an IP packet, it will just copy the IP TTL field into the MPLS Label TTL field.
• D. When an ingress edge LSR receives an IP packet, it will copy the IP TTL field into the MPLS Label TTL field first; then it will only decrement the MPLS Label TTL field by 1.
• E. When an ingress edge LSR receives an IP packet, it will copy the IP TTL field into the MPLS Label TTL field first; then it will only decrement the IP TTL field by 1.

Answer: B

NEW QUESTION 8
Referring to the Cisco IOS XR show command output exhibit,

what are three possible reasons that the GigabitEthernet0/1/0/10 LDP IGP sync status is not ready? (Choose three.)

• A. GigabitEthernet0/1/0/10 is not configured to run LDP.
• B. Graceful restart is not configured on the peer.
• C. The LDP neighbor on GigabitEthernet0/1/0/10 is not up.
• D. The OSPF neighbor on GigabitEthernet0/1/0/10 is not up.
• E. LDP is up on GigabitEthernet0/1/0/10, but no label bindings have been received from the peer.
• F. GigabitEthernet0/1/0/10 is a member link of Bundle-Ether9000.

Answer: CDE

NEW QUESTION 9
Which QoS technique can be used to protect customer traffic from being dropped by traffic rate limiting performed by the service provider?

• A. LLQ
• B. policing
• C. fair-queue
• D. shaping

Answer: D

NEW QUESTION 10
Which three mechanisms are used to implement MPLS TE? (Choose three.)

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

Answer: ABC

Explanation:
Constrained-Based Shortest Path First (CSPF).
Resource Reservation Protocol - Traffic Engineering is an extension of the resource reservation protocol (RSVP) for traffic engineering.

NEW QUESTION 11
At which layer does Cisco recommend the QoS trust boundary be set for an enterprise network environment?

• A. core layer, facing the distribution layer
• B. distribution layer, facing the access layer
• C. access layer, facing the end hosts
• D. distribution layer, facing the core layer

Answer: C

NEW QUESTION 12
Which driver uses an IntServ QoS model in an MPLS TE enabled service provider network?

• A. DSCP, which requires signaling across the provider network
• B. RSVP, which enables bandwidth guarantees across a provider network
• C. RSVP, which enables per-hop behavior across a provider network
• D. DSCP, which enables bandwidth guarantees across a provider network

Answer: B

NEW QUESTION 13
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

Answer: CE

NEW QUESTION 14
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)

B)

C)

D)

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

Answer: C

NEW QUESTION 15
An engineer is having a problem getting an operational 10 Gigabit link on a Cisco ASR 9000 series router. The service provider instructs the engineer to use an LR optic. The engineer must access the router remotely.
Which command should the engineer issue to determine that the correct optic has been installed?

• A. show controllers
• B. show module optics
• C. show ip interface
• D. show optics

Answer: A

NEW QUESTION 16
Which Cisco IOS XR command should be used in order to enable LDP on all interfaces for which the IGP protocol is enabled?

• A. RP/0/0/CPU0:R1(config-ospf)#mpls ldp auto-config
• B. RP/0/0/CPU0:R1(config-ospf)#mpls ldp interface all enable
• C. RP/0/0/CPU0:R1(config-ospf)#enable all
• D. RP/0/0/CPU0:R1(config-ldp)#enable all

Answer: A

NEW QUESTION 17
Which of the following three statements are correct regarding IPv6 QoS? (Choose three.)

• A. The traffic class field in the IPv6 header can be used to set specific precedence or DSCP values.
• B. A 20-bit flow label field enables per-flow processing.
• C. DS-TE is not supported by IPv6.
• D. Per-hop behavior in IPv6 networks is based on EXP bits.
• E. IPv6 QoS features are configured using the modular QoS CLI on Cisco routers.

Answer: ABE

Explanation:
http://www.cisco.com/en/US/technologies/tk648/tk872/technologies_white_paper0900aecd 8026004d.pdf

NEW QUESTION 18
Cisco MPLS TE path setup can be affected by which three tunnel attributes? (Choose three.)

• A. bandwidth
• B. delay
• C. MTU
• D. priority
• E. affinity

Answer: ADE

NEW QUESTION 19
Which Cisco IOS XR command should be used in order to enable LDP-IGP synchronization for the ISIS IGP protocol?

• A. RP/0/RSP0/CPU0:R1(config-isis-if-af)#mpls ldp sync
• B. RP/0/RSP0/CPU0:R1(config-isis)#mpls ldp sync
• C. RP/0/RSP0/CPU0:R1(config-ldp)#isis ldp sync
• D. LDP-IGP synchronization is not supported for the ISIS IGP protocol on Cisco IOS XR platforms

Answer: A

NEW QUESTION 20
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

Answer: ABCD

Explanation:
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.

NEW QUESTION 21
DRAG DROP
You create an MPLS TE tunnel in IOS XR Software and want to configure forwarding on the tunnel. Drag the steps on the left to their correct order on the right.
Select and Place:

• A. Mastered
• B. Not Mastered

Answer: A

Explanation:

NEW QUESTION 22
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 largestsample 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 theconfigured 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, ormaximum configured bandwidth value

Answer: A

NEW QUESTION 23
Which two options are able to perform the MPLS label distribution function? (Choose two.)

• A. manual tagging
• B. static
• C. LDP
• D. RSVP-TE
• E. CEF

Answer: CD

NEW QUESTION 24
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