Wan Services Isdn Ddr

8/9/2019 Wan Services Isdn Ddr

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Integrated Services Digital Network (ISDN)

ISDN is a set of standards that define an end-to-end digital network it is a circuit-switchedservice provided by telecoms providers to allow voice, data, and video and audio transmissionsover existing digital telephone lines. ISDN is often used as a low cost alternative to Frame Relay

or T1 connections while still offering a higher connection speed than an analog modem.

QuestionWhich circuit-switched WAN technology is often used to provide a backup for a leased line andadditional capacity during peak usage times?

X.25DSLISDNcable modem

Answer ISDN

ISDN is offered at two levels Basic Rate Interface (BRI) and Primary Rate Interface (PRI).

ISDN configurations Basic Rate Interface, or BRI. (In Europe, this service is called S0.) On asingle pair of ordinary phone wires, BRI offers two 64kbps "bearer" channels and one "data"channel at 16kbps. This configuration is often referred to as 2B+D. When ISDN BRI is installed inyour facility, each line is brought in on only one pair of wires.

PPP is typically used with ISDN to provide data encapsulation, link integrity and authentication.ISDN is an underlying infrastructure that PPP, HDLC or Frame Relay could use.


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ISDN Components

ISDN standards use function groups and reference points to describe the various components

that can be utilized in making an ISDN connection.

Below, Router 1 is a router without a BRI interface so it uses a TA (ISDN Modem) to connect to

the ISDN line. Router 2 has a BRI interface without a built-in NT1.

Router 3 has a BRI interface with a built-in NT1. Router 4 is attached to a line that uses a NT2device for the local PBX.

ISDN Connections

ISDN BRI is made up of two B channels of 64k each and one D channel of 16kISDN BRI routers come with either a U interface or an S/T interface


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The difference is the U interface is already the 2 wire ISDN convention that can plug into the localloop, the S/T interface is a four wire interface that needs an adapter(a Network termination type1 - NT1)

The U interface has a built-in NT1 device. If your service provider uses an NT1 device then youneed to buy a router that has an S/N interface.

ISDN Functions and Devices

Terminal Adapter (TA) --- A converter device that allows non-ISDN devices (TE2 devices such

as a pc, analogue phone or modem) to operate on an 2-wire ISDN network.

Terminal Equipment 1 (TE1) --- A device that supports ISDN standards and that can be

connected directly to an ISDN network connection. For example, routers with integrated ISDN

interfaces, ISDN telephones, personal computers, or videophones could function as TE1s.

Terminal Equipment 2 (TE2) --- A non-ISDN device, such as a serial interface on a router or a

standard pc, analogue phone or modem which requires a TA in order to connect to an ISDN

network.

Network Termination 1 (NT1) --- A small connection box that is attached to ISDN BRI lines. Thisdevice terminates the connection from the Central Office (CO). Converts BRI signals for use byISDN line. An (NT1) device implements the ISDN Physical Layer specifications and coverts the 4-wire user device to the 2-wire network used by ISDN. (A U reference point)

Network Termination 2 (NT2) --- A device that provides switching services for the internal

network. This type of interface is typically used with PRI lines, when they need to be divided for

several functions. For example, some channels may be used for WAN data communications and


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others for the telephone system (such as PBX) and/or video tele-conferencing. It is a more

complex NT1 that performs layer 2 and 3 functions.

The connection between two function groups (including cabling) is called a reference point.

ISDN Reference Points (ISDN has four reference points that define logical interfaces)

U --- The U-interface is the actual two-wire cable, also called the local loop that connects the

Customer Premise Equipment to the telecommunications provider. (only in America)

R--- The R-interface is the wire or circuit that connects the TE2 (non-ISDN equipment) to

the TA.

S --- The S-interface is a four-wire cable from TE1 or TA to the NT1 or NT2, which is a two-

wire termination point.

T --- The point between the NT1 and NT2 is the T-interface. This four-wire cable is used to

divide the normal telephone company's two-wire cable into four-wires, which then allows theconnection of up to eight ISDN devices.

S/T --- When NT2 is not used on a connection that uses NT1, the connection from the router

or TA to the NT1 connection is typically called S/T. This is essentially the combination of the

S and T reference points.

ISDN Protocols

ISDN protocols deal with diverse issues

Protocols beginning with the letter E deal with using ISDN on the existing telephone networkProtocols beginning with the letter I deal with concepts, aspects and services.Protocols beginning with the letter Q cover switching and signalling.


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The Q.921 protocol describes the ISDN Data Link process of the Link Access Procedure on the Dchannel (LAPD)

ISDN Operations

Link Access Procedure, D channel

Layer 2 of the ISDN signalling protocol is Link Access Procedure, D channel, also known as

LAPD, it is used by ISDN to pass the signalling messages between the router and the ISDN

switch at the local CO (Central Office). LAPD is similar to High-Level Data Link Control (HDLC)

and Link Access Procedure, Balanced (LAPB). As the expansion of the LAPD acronym indicates,

it is used across the D channel to ensure that control and signalling information flows and is

received properly. The data travels between routers on the B-channels via HDLC or PPP

encapsulation. The LAPD frame format is very similar to that of HDLC and, like HDLC, LAPD

uses supervisory, information, and unnumbered frames.

Configuring ISDN on Cisco Routers

Accessing ISDN with a Cisco router means that you will need to purchase either a Cisco router

with a built-in NT1 (U reference point) or an ISDN modem (called a TA). If your router has a BRI

interface (called a TE1), you only need attach an NT1 device to connect to the services. If your

router doesn't have a BRI interface (called a TE2), you need to attach a TA and a NT1 to connect

to ISDN services.

ISDN supports virtually every upper layer protocol (IP, IPX, AppleTalk), and you can choose PPP,

HDLC, or X.25 as the encapsulation protocol.

ISDN Switch Types

To configure a router for the variety of switches to connect to use the right identifier along withthe isdn switch-type commandRouter(config)#isdn switch-type [identifier]


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QuestionWhich of the following are valid steps for a basic ISDN BRI configuration? (Choose two.)

A. create subinterfacesB. define the LMI typeC. set the SPIDs if required by the ISDN switchD. set the interface DLCIE. set the switch typeF. specify the encapsulation as either Cisco or IETF

Answer C, ESet the SPIDs if required by the ISDN switchSet the switch type

Basic Rate Interface

ISDN BRI provides two bearer (B) channels, each capable of transferring voice or data at64 kbps, and one 16 kbps data (D) signaling channel, which is used by the telephone network tocarry instructions about how to handle each of the B channels. ISDN BRI(also referred to as 2 B + D) Total bandwidth for ISDN BRI, is then 144k (64+64+16=144)D channels work with LAPD at the Data Link Layer for reliable connections.

When configuring ISDN BRI, youll need to obtain service profile identifiers (SPIDs) and youshould have one SPID for each B channel. SPIDs can be thought of as the telephone number ofeach B channel. The ISDN device gives the SPID to the ISDN switch, which then allows thedevice to access the network for BRI or PRI service. Without a SPID many ISDN switches dontallow an ISDN device to place a call on the network.

To setup a BRI call, 4 events must take place.

1. The D channel between the router and the local ISDN switch comes up

2. The ISDN switch uses the SS7 signalling technique to setup a path to a remoteswitch

3. The remote switch sets up the D-channel link to the remote router4. The B channels are then connected end-to-end

Primary Rate Interface

In the US and Japan ISDN PRI service, (also known as 23B+D1) delivers 23 64Kbps B channelsand one 64Kbps D channel for a total bit rate of 1.544MbpsIn Europe and other parts of the world ISDN provides 30 64Kbps B channels and one 64Kbps Dchannel for a total bit rate of up to 2.048Mbps.


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For the exam you do not need to worry about how many PRI channels thereare only the BRI is tested

A system administrator needs to configure the regional office with ISDN for DDR connections tothree remote sites. Each remote site requires different IP subnets, different encapsulations, anddifferent authentication methods. The sites will not be connected at the same time. The companywould like to accomplish this in the most cost effective manner. What method can the systemadministrator use to accomplish this task using the fewest B channels?

A. Install and configure a PRI.B. Install and configure a BRI interface with separate SPIDs for each remote site.C. Install and configure a BRI with multiple switch types in global configuration.D. Install and configure a BRI using dialer profiles.E. Install and configure a separate BRI for each remote site.

Answer D

Install and configure a BRI using dialer profiles.


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Dial-on-Demand Routing (DDR)One frequent use of ISDN is as a backup to another WAN connection, such as Frame Relay.

When the Frame Relay link goes down, the ISDN automatically establishes a connection. Thetechnology that provides this backup connectivity is called dial-on demand routing (DDR)You can use DDR to allow two or more Cisco routers to dial an ISDN dial-up connection on an as

needed basis. DDR is used only for low-volume periodic network connections using PSTN orISDN designed to reduce WAN costs.

Configuring DDR

Define static routes, which define how to get to the remote networks and what interface to use toget there.Specify the traffic that is considered interesting to the router.Configure the dialler information that will be used to dial the interface to get to the remotenetwork.

Configuring Static Routes

To forward traffic across the ISDN link, you configure static routes in each of the routers, youcould configure dynamic routes but the link never drops therefore static is best.

When creating Static routesAll participating routers must have static routes defining all routes of known networksDefault routing can be used if the network is a stub network.

Static routing with ISDN

RouterA(config)#ip route 172.16.50.0 255.255.255.0 172.16.60.2

RouterA(config)#ip route 172.16.60.2 255.255.255.255 bri0

What this does is tell the router how to get to network 172.16.50.0 through 172.16.60.2The second line tells the router how to get to 172.16.60.2

Specifying Interesting Traffic

After setting the route tables in each router it is then determined what brings up the ISDN line. Anadministrator using the dialer-list global configuration command defines interesting packets.

The command to turn on all IP traffic is shown

804(config)#dialer-list 1 protocol ip permit804(config)#int bri0

804(config)#dialer-group 1

The dialer-group command sets the access list on the BRI interface. Extended access lists

can be used with the dialer-list command to define interesting traffic to just certain applicantsNote if you use the dialer-list command you must enter the dialer-group command on aninterface.Configuring the Dialer Information (5 steps)


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1. Choose the interface2. Set the IP address3. Configure the encapsulation type4. Link interesting traffic to the interface5. Configure the number/s to dial

Heres how to configure the 5 steps

804A#config t

804A(config-if)#int bri0

804A(config-if)#ip address 172.16.60.1 255.255.255.0

804A(config-if)#no shut

804A(config-if)#encapsulation ppp

804A(config-if)#dialer-group 1

804A(config-if)#dialer string 8350661

Instead of the dialer string command you can use a dialer map. It provides more security

804A(config-if)#dialer map ip 172.16.60.2 name 804B 8350661

You can use the dialer map command with the dialer group command and its associated

access list to initiate dialling. The dialer map command uses the IP address of the next hoprouter, the hostname of the remote router for authentication and the number to dial

Take a look at the configuration of an 804 router

804B#show run

Building configuration

Current configuration;

!

Version 12.0

No service pad

!Hostname 804B

!

ip subnet-zero

!

isdn switch-type basic-ni

!

interface Ethernet0

ip address 172.16.50.10 255.255.255.0

no ip directed-broadcast

!

interface BRIO

ip address 172.16.60.2 255.255.255.0

no ip directed-broadcast

encapsulation ppp

dialer idle-timeout 300

dialer string 8358661

dialer load-threshold 2 either

dialer-group 1

isdn switch-type basic-ni

isdn spid1 0835866201 8358662

isdn spid2 0835866401 8358664

hold-queue 75 in


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!

ip classless

ip route 172.16.30.0 255.255.255.0 172.16.60.1

ip route 172.16.16.1 255.255.255.255 BRIO

!

dialer-list 1 protocol ip permit

!

Looking at this output you can determine that the BRI interface is running the PPP encapsulationand it has a timeout value of 300 seconds. The load-thresholdcommand makes both

interfaces come up immediately.Note the dialer-group 1 command. That number must match the dialer-list number. The

hold-queue75in command tells the router that when it receives an interesting packet, it

should queue up to 75 packets while its waiting for the BRI to come up. If there are more than 75packets queued before the link comes up the packets will be dropped.

Optional Commands

There are two other commands that you should on your BRI interface the dialer load-

thresholdcommand and the dialer idle-timeout command.

The dialer load-thresholdcommand tells the BRI interface when to bring up the second B

channel. The option is from 1 to 255, where 255 tells the BRI to bring up the second B channel


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only when the first channel is 100% loaded. The second option for that command is in, out oreither.This calculates the actual load on the interface either on outbound traffic, inbound traffic orcombined. The default is outbound.

The dialer idle-timeout command specifies the number of seconds before a call is

disconnected after the last interesting traffic is sent. The default is 120 seconds.

RouterA(config-if)#dialer load-threshold 125 either

RouterA(config-if)#dialer idle-timeout 180

The dialer load-threshold 125 tells the BRI interface to bring up the 2nd B channel if

either the inbound or outbound traffic load is 50%. The dialer idle-timeout 180 changes the defaultdisconnect time from 120 to 180 seconds.

DDR with Access Lists

Use access lists to be more specific about what is or is not interesting traffic.Heres how to use the dialer list and access list.

804A(config)#dialer-list 1 list 110

804A(config)#access-list 100 permit tcp any any eq smtp

804A(config)#access-list 110 permit tcp any any eq telnet

804A(config)#int bri0

804A(config-if)#dialer-group 1

Create your list and apply it to the BRI interface with the dialer-group command.

QuestionBy looking at the configuration, Which additional command must be issued on the Branch router

before interesting traffic will be sent to the Remote router?

Hostname: Branch Hostname: RemotePH# 123-6000, 123-6001 PH# 123-8000, 123-8001SPID1: 32055512360001 SPID1: 32055512380001SPID2: 32055512360002 SPID2: 32055512380002

isdn switch-type basic niusername Remote password ciscointerface bri0ip address 10.1.1.1 255.255.255.0encapsulation pppppp authentication chap

isdn spid1 41055512360001isdn spid2 41055512360002dialer map ip 10.1.1.2 name Remote 1238001dialer-list 1 protocol ip permit

A. (config-if)# dialer-group 1B. (config-if)# dialer-list 1C. (config-if)# dialer map 1D. (config-if)# dialer-route 1


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Answer A

ExplanationThe "dialer-group #" command tells the access-list (used with the dialer-list # command), whichinterface to activate when it finds interesting traffic. The numbers at end of each command mustmatch.

QuestionWhat must you do to test connectivity on a dial on demand routing (DDR) link?

A. Increate the idle import parameter.B. Send interesting traffic across the link.C. SwitchD. Repeater

Answer B

Explanation

To test DDR connectivity you will need to send interesting traffic across the link.

Incorrect AnswersA. This will not have the desired result.C and D. These devices will not allow you to test connectivity.

QuestionWhat are two of the steps required to configure a router to connect over ISDN BRI?(Choose two.)

A.Configure the interface with a DLCI.B. Configure the SPIDs, if required by the ISDN switch.

C. Specify the the LMI type to be compatible with the CO switch.D. Set the interface encapsulation to the Cisco or IETF frame type.E. Configure a subinterface for each B channel.F. Set the switch type to work with the ISDN switch at the CO.

Answer A, B

Configure the interface with a DLCI and Configure the SPIDs, if required by the ISDN switch.

ExplanationA as The Data Link Connection Identifier (DLCI) indicates the Frame Relay PVC (PermanentVirtual Circuit) you wish to use! Both sides need to be configured correctly and the circuit will bemade.

PVCs are identified to routers using DLCIs these are channel numbers which is attached to framerelay data frames to tell the network how to route the data Frame relay that is multiplexed, whichmeans that only one frame can be transmitted at a time but many logical connections can co-existon a single physical line. The DLCI allows the data to be logically tied to one of the connectionsso that once it gets to the network it knows where to send it.

B as When configuring ISDN BRI, youll need to obtain service profile identifiers (SPIDs) and youshould have one SPID for each B channel. SPIDs can be thought of as the telephone number ofeach B channel. The ISDN device gives the SPID to the ISDN switch, which then allows the


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device to access the network for BRI or PRI service. Without a SPID many ISDN switches dontallow an ISDN device to place a call on the network.

Not C as LMI is a signalling standard used to transmit messages between your router and the firstFrame Relay switch to which its connected. LMI allows information to be passed about theoperation and status of the VC between the providers network and the DTE (your router)Remember LMI isnt communication between your routers its communication between your routerand the nearest Frame Relay Switch as to whether its active or inactive.

Not D as is doesnt say if the routers are Cisco, non-Cisco or a mix. Encapsulation on ISDN BRIEach ISDN B channel is treated as a synchronous serial line, and the default serial encapsulationis HDLC. The Dynamic Multiple Encapsulations feature introduced in Cisco IOS Release 12.1allows incoming calls over ISDN to be assigned an encapsulation type such as Frame Relay,PPP, and X.25 based on CLID or DNIS. PPP encapsulation is configured for most ISDNcommunication.

Not E as creating subinterfaces allow you to have multiple virtual circuits on a single serialinterface and treat each as a separate interface.

Link Access Procedure, D channel, also known as LAPD, it is used by ISDN to pass the signallingmessages between the router and the ISDN switch at the local CO (Central Office). LAPD isused across the D channel to ensure that control and signalling information flows and is receivedproperly. The data travels between routers on the B-channels via HDLC or PPP encapsulation.

QuestionHow are the settings for ISDN switch type and SPIDs determined for a BRI interfaceconfiguration?

A. assigned by the network administratorB. randomly, so long as they are not duplicated on the network

C. by trial and errorD. dynamically via Inverse ARPE. assigned by IANAF. assigned by the service provider

Answer A

They are assigned by the network administrator

QuestionA Router with a BRI/T interface will be used for an ISDN Connection what other ISDN device is

required to complete this connection?

A. TE1B. TE2C. NT1D. NT2

Answer C

Explanation


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NT1 is used to connect Service Provider.Incorrect answersA. TE1 is used for connecting ISDN TerminalB. TE2 is used for connecting non ISDN terminal with TAD. NT2 Equipment that uses T interface point to Telco outside North America

QuestionOnce you have defined interesting traffic with the dialer-list command, you then must associatean ISDN phone number with the next hop router address. Which IOS command should you use?

A. Isdn destination number.B. Dialer map.C. Isdn spid1.D. Isdn line number.

Answer B

Explanation

The dialer map command is used to define one or more dial-on-demand numbers to reach one ormore destinations for a particular interface. This is the exact command to associate an ISDNphone number with the next hop router address.

Incorrect AnswersA. This is not a valid command.C. The isdn spid1 command specifies the SPID required for b channel to access the ISDNnetwork when your router makes its call to the local ISDN exchange.D. This is not a valid command.

Question

Central Partial Configurationisdn switch-type basic-niusername Remote

password kinginterface bri0ip address 10.1.1.1 255.255.255.0encapsulation pppppp authentication chapisdn spid1 51055512360001isdn spid1 51055512360002dialer map ip 10.1.1.2name Remote1238001dialer-list 1 protocol ip permit


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Your company is using ISDN to connect the Remote office to the Central office. The connectionis not working between the two routers. You issue the show running-config command looking atthe configuration above. Which additional command must be issued on the Central router beforeinteresting traffic will be sent to the Remote router?

A. (config-if)# dialer-group 1B. (config-if)# dialer-list 1C. (config-if)# dialer map 1D. (config-if)# dialer-route 1

Answer A

ExplanationOnce the above commands have been entered to enabled DDR, then the last step required is tobind the traffic destination to an interface by linking the interesting traffic definition alreadycreated. This is done with the dialer-group command. In this case the proper command wouldbe (config-if)# dialer-group 1.

Incorrect AnswersB. The interesting traffic was already identified the first time the dialer-list 1 command was used.

C. The dialer map command is used to identify the router to be dialed. In this case this hasalready been done.D. There is no such thing as a dialer route command.

QuestionYour company has decided to use a (BRI) connection between the Florida office and the Georgiaoffice. You would like to configure dial on demand routing (DDR) on this connection. Which of thefollowing commands are required to setup DDR? (Choose three)

A. Define static routes.B. Configure the dialer information.C. Specify interesting traffic that can enable the link.

D. Define DDR password to exchange when the link comes up.

Answer A, B, C

ExplanationTo configure standard DDR, the following steps are required:Define static routes - What route do I take to get to the destination?Specify interesting traffic - What traffic type should enable the link?Configure the dialer information; What number do I call to get to the next hop router, and whatservice parameters do I use to call?

Incorrect AnswersD. Defining a DDR password is not required.

QuestionYou have just configured DDR (Dial on Demand Routing) and would like to test the link. What canyou use to bring up the connection?

A. Increase the idle timeout parameter.B. Send interesting traffic across the link.C. Reboot one of the Integrated Services Digital Network (ISDN) routers.D. Reset the DDR Integrated Services Digital Network (ISDN) router statistics to zero.


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Answer B

ExplanationOf the options provided above the best way to determine if there is connectivity on a dial-on-demand routing link is to send interesting across the link. If there is connectivity a link will beinitiated and established to send the interesting traffic. If there is no connectivity then the link willnot be established.

Incorrect AnswersA. Increasing the idle time parameter will only result in increasing the idle time.C. Rebooting the router will only result in the router going through its post.D. This action will not confirm whether a DDR has connectivity or not.

QuestionWhich two are facts about integrated services digital network (ISDN)? (Choose two)

A. ISDN provides only data only capability.B. ISDN provides an integrated voice/data capability.C. The ISDN standards define the hardware and call setup schemes for end-to-end digitalconnectivity.

D. Users receive more bandwidth on WANs with a leased line of 56kbps than with multiple Bchannels.

Answer B, C

ExplanationISDN stands for Integrated Services Digital Network. ISDN refers to a collection of standards thatdefine a digital architecture that provides an intergraded voice/data capability to customers'premises facility. The ISDN standards define the hardware and call setup schemes for end-to-end digital connectivity.

Incorrect AnswersA. ISDN provides for voice and data capability.

D. BRI offers a total of 144 kbps and ISDN PRI offers even more.

QuestionIn today's networks which encapsulation methods are most commonly used (ISDN)?

A. IP and IPXB. IP and PPPC. PPP and SDLCD. PPP and HDLC

Answer D

ExplanationThere are a number of WAN encapsulation types available. The two most commonly used arePoint-to-Point Protocol (PPP) and Cisco High-Level Data Link Control (HDLC). The reason HDLCis employed so much is that it is the default encapsulation type on point-to-point dedicated linksand circuit switched connections. PPP is a non-proprietary encapsulation and this is while it isused to communicate between devices from different vendors.Incorrect AnswersA. IP and IPX are not encapsulation types. They are routing protocols.B. Only PPP is an encapsulation type.


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C. SDLC is a protocol used in IBM SNA systems.

QuestionWhich of the following belong to the ISDN TE2 function group? (Choose two)

A. A standard PC.B. An ISDN phone.C. An ISDN terminal adapter.D. A router serial interface.E. A router ISDN BRI "U" interface.

Answer A, D

ExplanationTE2 is used to connect any non-isdn device by using TA (Terminal adaptor). In this exampleStandard PC and router serial interface on non-ISDN Terminals. Router BRI or PRI interface areISDN compatible ports.

Incorrect answersB, C, E. Theses are ISDN compatible devices. It uses ISDN TE1 function.

Question

Which of the following is the minimum configuration commands required to bring up the ISDN linkshown in graphic.Note : SPIDs are not required for this switch. (Choose three)

A. Router(Config-if)# encapsulation pppB. Router(Config-if)# isdn switch-type typeC. Router(Config-if)# dialer-list, protocol ip permitD. Router(Config-if)# dialer map ip address name name connection number.E. Router(Config-if)# ip address subnet maskF. Router(Config-if)# dialer group 1

Answer A, E, F

Explanation

A. Proper encapsulation to be defined on both routers.E. IP address to be assigned for interface with subnet maskF. Dialer group number enables dialer-list on this interface. Dialer-list to be defined on gloabalconfiguration command.

Incorrect AnswersB, C. The commands are executed on global configuration command.D. Syntax is wrong. Proper syntax is dialer map ip address/subnet mask name connection namenumber.


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QuestionWhich of the following are reference points relevant to ISDN? [Select 2].A. TB. U

C. VD. X

Answer A, B

ExplanationISDN uses four different reference points to define logical interfaces:1. R-reference point. Defines the reference point between non-ISDN compatible devices and aTerminal Adapter (TA).2. S-reference point. Defines the reference point between user terminals and an NT2.3. T-reference point. Defines the reference point between NT1 and NT2.4. U-reference point. Defines the reference point between NT1 devices and line-terminationequipment in a carrier network.The flow of reference points are:[TE2] ---R--->[TA]---S/T--->[NT1]--->U--->to carrier[TE2]--->R--->[TA]--->S--->[NT2]--->T--->[NT2]--->to carrier

QuestionYou are a systems administrator of an HR company in Dallas. You want to connect yourcompany's head office with a branch office in Detroit. To do this, you want to use two data linklayer encapsulations: one exclusively for data and the other exclusively for signaling. Which oneof the following WAN services would best suit your needs?

A. ISDNB. ATMC. FDDID. ATX

E. Frame Relay

Answer A

ExplanationISDN Q.931 messages are used for signaling via the ISDN D channel.ISDN B channels are used to transport data.

QuestionA router with a serial interface will be used for an ISDN link.

What other function group devices are required to complete the connection to the service

provider? (Choose two)

A. TE1B. TE2C. TAD. NT1E. NT2

Answer C, D


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ExplanationC. TA is used connect Non ISDN Device. Serial Interface is non-ISDN port. BRI Port is IDSN port.D. NT1 is required to Connect to Service Provider. It converts 2-wire line from Service Providerinto 4-wire line.Incorrect answersA. TE1 is used to connect ISDN Terminal.B. TE2 is used to connect non-ISDN terminal via TAE. Equipment that uses T interface point to Telco outside North America

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