Ensurepass

QUESTION 21

The regional operation center deploys a Cisco MPLS TE tunnel over the company’s core network. The Cisco MPLS TE tunnel is up and no error is detected, but no traffic is traversing the tunnel. Which two issues are possible causes? (Choose two.)

 

A.

The provider edge router is not performing the correct redistribution.

B.

The interior gateway protocol has no knowledge of the Cisco MPLS TE tunnel.

C.

No static route has been defined to route data traffic over the Cisco MPLS TE tunnel.

D.

The customer edge router is injecting rogue IPv4 prefixes in the provider edge routing table.

E.

The end-to-end label switched path has not been established.

 

Correct Answer: BC

 

 

QUESTION 22

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

 

Correct Answer: B

 

 

QUESTION 23

Which method is used to mark traffic matched by class-map MY_CLASS as Expedited Forwarding?

 

A.

set ip dscp cs7

B.

set dscp cs7

C.

set dscp 46

D.

set dscp 45

 

Correct Answer: C

 

 

QUESTION 24

Which two fields are in the traffic engineering top
ology database? (Choose two.)

 

A.

TE-metric

B.

IGP metric

C.

link delay

D.

LSP setup priority

E.

LDP authentication

 

Correct Answer: AD

 

 

 

 

 

QUESTION 25

On Cisco routers, how is hierarchical QoS implemented?

 

A.

Within the parent policy, reference another child policy using the policy-map command.

B.

Within the child policy, reference another parent policy using the policy-map command.

C.

Use the policy-map command within a service-policy to implement nested policy-maps.

D.

Within the parent policy-map, reference another child policy-map using the service- policy command.

 

Correct Answer: D

 

 

QUESTION 26

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

 

A.

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

B.

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

C.

They use ICMP echo request and ICMP echo reply packets.

D.

They are used to test for a broken LSP.

E.

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.

 

Correct Answer: ABD

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 127.0.0.1. The IP TTL will be set to 1.

 

Below is a sample IP format when MPLS Ping is originated from R5 to 150.1.6.6/32.

 

clip_image002

 

Now the originating LSR will look into the LFIB and populate the label header with respective labels to reach the FEC, in our case 150.1.6.6/32.

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 127.0.0.1 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 127.0.0.0/8

QUESTION 27

DS-TE implementations on Cisco routers support which bandwidth pool(s) and class type(s)? (Choose two.)

 

A.

global pool only

B.

subpool only

C.

global pool and subpool

D.

class-type 0 only

E.

class-type 1 only

F.

class-type 0 and class-type 1

 

Correct Answer: CF

Explanation:

Differential Service Tunnels

Differential Service Traffic Engineering (TE) is an extension of the regular MPLS Traffic Engineering (MPLSTE) feature. Regular TE does not provide bandwidth guarantees to different traffic classes. A single bandwidth pool (global pool) is used in regular TE that is shared by all traffic. In order to support various class of service (CoS), the ability to provide multiple bandwidth pools is required. These bandwidth pools then can be treated differently based on the requirement for the traffic class using that pool.

 

In RSVP global and subpools reservable bandwidths are configured on a per interface basis to accommodate TE tunnels on the node. Available bandwidth from all c
onfigured bandwidth pools is advertised using Interior Gateway Protocol (IGP). RSVP is used to signal the TE tunnel with appropriate bandwidth pool requirements.

 

 

QUESTION 28

An engineer is tasked to deploy Fast Reroute for Cisco MPLS TE. Which LSR is in charge to request the Fast Reroute capability along the LSP?

 

A.

point of local repair

B.

tail end router

C.

ingress and egress PE routers

D.

head-end router

E.

BGP routers acting as route reflectors

 

Correct Answer: D

 

 

QUESTION 29

A service provider recently defined new SLA services that provide QoS transparency over MPLS DiffServ-TE services. Which two tunneling modes provide QoS transparency? (Choose two.)

 

A.

short pipe mode

B.

uniform mode

C.

pipe mode with an explicit NULL LSP

D.

pipe mode without a explicit NULL LSP

E.

best effort mode

 

Correct Answer: AC

 

 

 

QUESTION 30

When a link flaps, an mpls ldp session will also flap. Which feature minimizes traffic loss and provides faster convergence after the link is re-established?

 

A.

BFD

B.

MPLS LDP IGP SYNC

C.

graceful restart

D.

LDP session protection

E.

LDP nonstop routing

 

Correct Answer: D

 

Free VCE & PDF File for Cisco 642-887 Real Exam

Instant Access to Free VCE Files: CCNA | CCNP | CCIE …
Instant Access to Free PDF Files: CCNA | CCNP | CCIE …

Comments are closed.