Ensurepass

QUESTION 181

Which two things are correct about QinQ technology? (Choose two.)

 

A.

The Outer.1Q tag represents customer VLAN ID and inner.1Q tag represents Service Provider VLAN (PVLAN)

B.

It is an effective way to achieve VLAN transparency between Provider and enterprise customer by tunneling one ser of VLAN tags inside a second VLAN tag

C.

The Outer.1Q tag represents Service Provider VLAN (PVLAN) and inner.1Q tag represents customer VLAN

D.

QinQ is a way to hide native VLAN which can conflict with Provider native VLAN

 

Correct Answer: BC

Explanation:

IEEE 802.1ad[note 1] is an Ethernet networking standard informally known as IEEE 802.1QinQ[by whom?] and is an amendment to IEEE standard IEEE 802.1Q-1998. The technique is also known as provider bridging, Stacked VLANs, or simply QinQ or Q-in-Q. “Q-in-Q” can for supported devices apply to C-tag stacking on Ctag (Ethernet Type = 0x8100) but this has limited application in the modern methodology of network routing.

The original 802.1Q specification allows a single Virtual Local Area Network (VLAN) header to be inserted into an Ethernet frame. QinQ allows multiple VLAN headers to be inserted into a single frame, an essential capability for implementing Metro Ethernet network topologies. Just as QinQ extends 802.1Q, QinQ itself is extended by other Metro Ethernet protocols.[specify]

In a multiple VLAN header context, out of convenience the term “VLAN tag” or just “tag” for short is often used in place of “802.1Q VLAN header”. QinQ allows multiple VLAN tags in an Ethernet frame; together these tags constitute a tag stack. When used in the context of an Ethernet frame, a QinQ frame is a frame that has 2 VLAN 802.1Q headers (double-tagged).

There is a mild confusion regarding the naming because the 802.1ad standard was grown out of the 802.1QinQ[citation needed] protocol (which was developed based the trademarked method 802.1Q, with capital “Q” as a distinction instead of the 802.1q as the standardised protocol) which originally used 0x8100 as ethernet type instead of 0x88a8.

While the network industry usually mix the naming, the proper, standardized name is 802.1ad which sometimes gets appended by the other alternative names mentioned above; the plain “802.1QinQ”[citation needed] name usually refers to the old standard which is now[when?] considered obsolete.

QUESTION 182

When should traffic shaping be implemented on Frame Relay PVCs? (Choose two)

 

A.

When you want to drop excess traffic above the CIR

B.

When there is a speed mismatch between the central site and the remote site.

C.

When using Frame Relay SVCs

D.

When over-subscribing the central site link

E.

When LLQ is implemented on the Frame Relay PVC.

F.

When Multilink PPP LFI is implemented on the Frame Relay PVC.

 

Correct Answer: BD

 

 

QUESTION 183

What is the purpose of Dual Ring Interconnect with D C for SDH rings?

 

A.

Protects signals when a ring switch fails

B.

Protects signals when multiple span switches fail

C.

Protects pre-emptible traffic from being dropped when a ring switch occurs

D.

Protects signals against any combination of link failure in each ring

 

Correct Answer: D

 

 

QUESTION 184

What is the effect of changing DMT interleaved delay from 3 milliseconds to 15 milliseconds?

 

A.

Latency remains the same, but throughput is decreased.

B.

Latency remains the same, but error correction effectives may also be reduced.

C.

Latency is increased, but faster error correction occurs.

D.

Fewer ATM PVCs can be provisioned on DSL line.

 

Correct Answer: C

 

 

QUESTION 185

In Ethernet Aggregation application which option is needed when the U-PE connects to an N-PE and broadband remote access servers?

 

A.

Ethernet Multipoint Service (EMS)

B.

VPLS

C.

E1

D.

Wire Service

 

Correct Answer: A

 

 

QUESTION 186

Which three of these statements about PPPoE are true? (Choose three.)

 

A.

PPPoE can provide a host with access to a destination over Ethernet. You can have only one PPPoE session per PVC.

B.

You must install PPPoE client software on all hosts that connect to the Ethernet segment. This means that the access provider must maintain a CPE.

C.

You cannot use PPPoE with Cisco Service Selection Gateway.

D.

PPPoE implementation is susceptible to broadcast storms and possible denial-of-service attacks.

E.

Per-session accounting is possible, which allows the service provider to charge the subscriber based on session time for various services offered. The service provider can also require a minimum access charge.

 

Correct Answer: BDE

 

 

QUESTION 187

In a cable HFC plant, what is a modulator?

 

A.

Set top box

B.

Diplex filter

C.

Local head end

D.

Fiber node

 

Correct Answer: A

 

 

QUESTION 188

Which four of these key points should be considered during implementation of PPPoA architecture? (Choose four)

 

A.

The number of subscribers that will be serviced currently and in the future because this affects the number of required PPPoA sessions

B.

The types of applications that the NSP offers to the end subscriber

C.

The capacity of ATM and Frame Relay interworking on the NSP

D.

In the case of more than one user, whether all users need to reach the same final destination or service, or they all have different service destinations

E.

Whether the service provider or the final service destination is providing the IP address to the CPE of the subscriber

 

Correct Answer: ABDE

Explanation:

Implementation Considerations for PPPoA Architecture

The number of subscribers that will be serviced currently and in the future, as this affects the number of required PPP sessions.

Whether the PPP sessions are being terminated at the service provider aggregation router or forwarded to other corporate gateways or Internet Service Providers (ISPs).

Whether the service provider or the final service destination is providing the IP address to the subscriber’s CPE.

Whether the IP addresses provided are legal public or private. Is the CPE going to do NAT/PAT or will NAT be performed at the termination destination?

Profiles of end subscribers, residential users, small office home office (SOHO) customers,and telecommuters.

In the case of more than one user, whether all users need to reach the same final destination or service, or they all have different service destinations.

Is the service provider providing any value added services like voice or video? Does the service provider require all subscribers to first go to a particular network before reaching a final destination? When subscribers use SSG, are they going to use passthrough services, PPP Terminated Aggregation (PTA), a mediation device, or proxy?

 

How the service provider bills subscribers–based on a flat rate, per session usage, or services used.

Deployment and provisioning of CPEs, DSLAMs and aggregation points of presence (POPs).

The business model for the NAP. Does the model also include s
elling wholesale services like secure corporate access and value added services like voice and video? Are NAPs and NSPs the same entity?

 

The business model of the company. Is it comparable to an independent local exchange carrier (ILEC), a competitive local exchange carrier (CLEC) or an ISP?

The types of applications the NSP will offer to the end subscriber.

The anticipated upstream and downstream volume of data flow.

Keeping these points in mind, we will discuss how the PPPoA architecture will fit and scale to different business models for service providers and how the providers can benefit using this architecture.

 

 

QUESTION 189

Typical ADSL broadband Internet access requires a username and password to be entered on end-user PC connected to the ADSL modem in order for the end user to gain access to the Internet. If a Cisco ADSL router is used instead of an ADSL modem, what functionality is required on the Cisco ADSL router so the end-user connected to the Cisco ADSL router can access the Internet without entering a username and password?

 

A.

Route Bridge Encapsulation (RBE)

B.

PPPoA

C.

Integrated Routing and Bridging (IRB)

D.

AAA

E.

PPPoE client

 

Correct Answer: E

 

 

QUESTION 190

What is the effect of turning on all available downstream carrier tones in a DMT DSL transmission systems?

 

A.

Downstream RS error correction effectiveness is reduced.

B.

The downstream line rate and throughput remains unchanged, but FEC efficiency is reduced.

C.

The upstream DSL bandwidth is reduced, since less carriers become available for upstream traffic.

D.

The downstream DSL bandwidth is increased.

 

Correct Answer: D

 

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