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       1 CCNA Semester 4 Chapter 04 Chap ter 04 ISDN and DDR ISDN and DDR 

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1

CCNA Semester 4

Chapter 04Chap

ter 04

ISDN and DDR ISDN and DDR

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ObjectivesObjectives

• Define the ISDN standards used for addressing,concepts, and signaling

• Describe how ISDN uses the physical and data linklayers

• List the interfaces and reference points for ISDN• Configure the router ISDN interface• Determine what traffic is allowed when configuring

DDR

• Configure static routes for DDR• Choose the correct encapsulation type for DDR• Be able to determine and apply an access list

affecting DDR traffic

• Configure dialer interfaces

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Table of ContentTable of Content

1 ISDN Concepts2 ISDN Configuration3 DDR Configuration

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ISDN CONCEPTSISDN CONCEPTS

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Introducing ISDNIntroducing ISDN

• The ISDN standards define the hardware and call setupschemes for end-to-end digital connectivity

• ISDN allows digital signals to be transmitted over existingtelephone wiring

• ISDN brings digital connectivity to local sites. Thefollowing list provides some of the benefits of ISDN:– Carries a variety of user traffic signals, including data, voice,

and video

– Offers much faster call setup than modem connections– B channels provide a faster data transfer rate than modems– B channels are suitable for negotiated Point-to-Point Protocol

(PPP) links

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Introducing ISDN (cont.)Introducing ISDN (cont.)

• ISDN uses out-of-band signaling, the delta (Dchannel), for call setup and signaling

• ISDN uses bearer channels, also called Bchannels, as clear data paths. Each B channelprovides 64 kbps of bandwidth.

• Each ISDN B channel can make a separateserial connection to any other site in the ISDNnetwork

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ISDN Standards And Access MethodsISDN Standards And Access Methods

• E Protocols – Recommend telephone networkstandards for ISDN. For example, the E.164 protocoldescribes international addressing for ISDN.

• I Protocols – Deal with concepts, terminology, andgeneral methods. The I.100 series includes generalISDN concepts and the structure of other I-seriesrecommendations. I.200 deals with service aspects of ISDN. I.300 describes network aspects. I.400describes how the UNI is provided.

• Q Protocols – Cover how switching and signalingshould operate. The term signaling in this contextmeans the process of establishing an ISDN call.

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ISDN Standards And Access Methods (cont.)ISDN Standards And Access Methods (cont.)

• ISDN specifies two standard access methods, BRI

and PRI.• BRI uses two 64 kbps B channels plus one 16kbps Dchannel.

• ISDN is considered a circuit-switched connection.• The D channel carries signaling messages to control

calls on B channels

BRI

PRI

NT1

CSU/DSU

ServiceProviderNetwork

D 2B

D 23B or 30B

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ISDN 3-layer Model And ProtocolsISDN 3-layer Model And Protocols

• ISDN utilizes a suite of ITU-T standards spanning the physical,data link, and network layers of the OSI reference model

OSI Layer D-Channel B-Channel

3 Q.931 – ISDN network Layerbetween terminal Switch

IP,IPX

2 Q.921 – LAPD PPPHDLC1 I.430/I.431 – ISDN physical-layer interface

- I.430 for basic interface

- I.431 for primary interface

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ISDN 3-layer Model And Protocols (cont.)ISDN 3-layer Model And Protocols (cont.)

- ISDN BRI frames contain 48 bits.

- Four thousand of these frames are transmittedsec.

- Each B channel, B1and B2, have a capacity of 64 kbps

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ISDN 3-layer Model And Protocols (cont.)ISDN 3-layer Model And Protocols (cont.)

• LAPD is similar to HDLC.

• LAPD is used across D channel to ensure thatcontrol & signaling information is received and

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ISDN FunctionsISDN Functions

ISDNServiceProvider

T i m e

Calling Party Called Party

Call setup

Setup Ack

Call preceding

Alert

Connect

Connect Ack Connect Ack

Connect

AlertCall preceding

Setup

• To establish an ISDN call, the D channel isused

between the router and the ISDN switch.

• Signal System 7 (SS7) signaling is used

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ISDN componentsISDN components

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ISDN component:ISDN component: TETE

• Specialized ISDN terminals are referred to as Terminal Equipment type 1 (TE1).

– Connect to the ISDN network through a four-wire,twisted-pair digital link.

• Non-ISDN terminals such as DTE that predatethe ISDN standards are referred to as

Terminal Equipment type 2 (TE2).

– Connect to the ISDN network through a TA.– The ISDN TA can be either a standalone device ora board inside the TE2. If the TE2 is implementedas a standalone device, it connects to the TA via astandard physical-layer interface.

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ISDN component:ISDN component: NTNT

• Network Termination type 1 (NT1) or Network Termination type 2 (NT2) device.

• These are NT devices that connect the four-wire subscriber wiring to the conventionaltwo-wire local loop.– In North America, the NT1 is a Customer Premises

Equipment (CPE) device.– In most parts of the world, the NT1 is part of the

network provided by the carrier.• The NT2 is a more complicated device, thatperforms L2 and L3 protocol services.

• An NT1/2 is a single device that combines thefunctions of an NT1 and an NT2.

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ISDN component:ISDN component: TATA

• TAs connect to workstations or non-ISDNrouter by externally through thecommunications ports (such as RS-232) and

can be used similarly to analog (such as V.34)internal and external modems.• TAs can provide a single PC user with direct

control over ISDN session initiation andrelease, similar to using an analog modem.

• Automated mechanisms must be provided tosupport the addition and removal of thesecondary B channel. Cisco 200 Series PCcards can provide ISDN services to a PC.

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ISDN Reference PointsISDN Reference Points

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ISDN reference pointsISDN reference points

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Determining The Router ISDN InterfaceDetermining The Router ISDN Interface

• Determine whether the router supportsISDN BRI.• Determine the provider of the NT1.• If the NT1 is CPE, make sure the router ha U

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ISDN Switch TypesISDN Switch Types

• Services offered by ISDN carriers varyconsiderably from country to country orregion to region

• Routers must be configured to identify thetype of switch with which they willcommunicate– E.g: net3, net5, 5ess,DMS-100,vn2,vn3,…etc

• there may also be necessary to know whatservice profile identifiers (SPIDs) are assignedby the telco.

• Each SPID points to line setup andconfiguration information

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ISDN CONFIGURATION

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Configuring ISDN BRIConfiguring ISDN BRI

• Step 1: Specify the ISDN switch type• Router(config)# isdn switch-type switchtype• Router(config-if)# isdn switch-type switchtype• Configuring the isdn switch-type command in

the global configuration mode sets the ISDNswitch type identically for all ISDN interfaces.

• Individual interfaces may be configured, afterthe global configuration command, to reflect analternate switch type.

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Configuring ISDN BRIConfiguring ISDN BRI

• Step 2: (Optional) Specify the SPIDs• Router(config-if)# isdn spid1 spid-number

[ldn ]Router(config-if)# isdn spid2 spid-number [ldn ]

• The optional ldn argument defines a local dialdirectory number

• the ldn number must match the called partyinformation coming in from the ISDN switch.

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Configuring ISDN PRIConfiguring ISDN PRI

• ISDN PRI is delivered over a leased T1 or E1line. The main PRI configuration tasks are asfollows:– Specify the correct PRI switch type that the router

interfaces with at the CO of the ISDN provider.– Specify the T1/E1 controller, framing type, and

line coding for the facility of the ISDN provider.– Set a PRI group timeslot for the T1/E1 facility and

indicate the speed used.

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Configuring ISDN PRIConfiguring ISDN PRI

• Step 1: Specify the isdn switch-type• Use the isdn switch-type command to

specify the ISDN switch used by the providerto which the PRI connects.– Router(config)# isdn switch-type primary-net5

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Configuring ISDN PRIConfiguring ISDN PRI

• Step 2: Configure controller– Task1: specify the controller and the slot/port in the

router where the PRI card is located:Router(config)# controller { t1 | e1 } { slot / port }

– Task2: Configure the framing, line coding, andclocking• For T1, use the following command syntax:

– Router(config-controller)# framing { sf | esf }

• For E1 lines, use the framing command with the followingoptions:– Router(config-controller)# framing { crc4 | no-crc4 } [ australia ]

• Use the linecode command to identify the physical-layersignaling method on the digital facility of the provider:

– Router(config-controller)# linecode { ami | b8zs | hdb3 }

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Configuring ISDN PRIConfiguring ISDN PRI

• Step 2: Configure controller– Task 3 : Configure the specified interface for PRI

operation and the number of fixed timeslots that

are allocated on the digital facility of the provider:Router(config-controller)# pri-group [timeslots range ]

– Task 4 : Specify an interface for PRI D-channel

operation. The interface is a serial interface to a T1/E1 on the router:Router(config)# interface serial { slot/port: |

unit: }{ 23 | 15 }

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Configuring ISDN PRI ExampleConfiguring ISDN PRI Example

Router(config)# controller e1 1/0Router(config-controller)# framing crc4Router(config-controller)#linecode hdb3Router(config-controller)#pri-group timeslots 1-

31Router(config-controller)#interface s3/0:15

Router(config-if)# isdn switch-type primary-net5

Router(config-if)#ip addre 10.10.10.1

255.255.255.0

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Verifying ISDN ConfigurationVerifying ISDN Configuration

• To confirm BRI operations, use the show isdnstatus command to inspect the status of the BRIinterfaces

• Verify that Layer 1 Status is ACTIVE, and that theLayer 2 Status stateMULTIPLE_FRAME_ESTABLISHED appears.

• The show isdn active command displays currentcall information, including all of the following:– Called number– Time until the call is disconnected– Charging units used during the call

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Verifying ISDN Configuration (cont)Verifying ISDN Configuration (cont)

• The show dialer command displaysinformation about the dialer interface:

– Current call status– Dialup timer values– Dial reason– Remote device that is connected

• The show interface bri0/0 displaysstatistics for the BRI interface configured onthe router.

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Troubleshooting The ISDN ConfigurationTroubleshooting The ISDN Configuration

• The debug isdn q921 command shows datalink layer, or Layer 2, messages on the Dchannel between the router and the ISDN

switch• The debug isdn q931 command shows the

exchange of call setup and teardownmessages of the Layer 3 ISDN connection.

• debug ppp authentication • debug ppp negotiation • debug ppp error

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3

DDR CONFIGURATION

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DDR OverviewDDR Overview

• Dial-on-demand routing (DDR) is triggeredwhen traffic that matches a predefined set of criteria is queued to be sent out a DDR-

enabled interface.• The traffic that causes a DDR call to be

placed is referred to as interesting traffic.

• Once the router has transmitted theinteresting traffic, the call is terminated• The key to efficient DDR operation is in the

definition of interesting traffic.

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DDR OperationDDR Operation

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Configuring Legacy DDR Configuring Legacy DDR

• To configure legacy DDR perform thefollowing steps:– Define static routes– Specify interesting traffic

– Configure the dialer information

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Defining Static Routes For DDR Defining Static Routes For DDR

22

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Specifying Interesting Traffic For DDR Specifying Interesting Traffic For DDR

• Use the dialer-list command to identifyinteresting traffic. The command syntax is asfollows:

• Router(config)# dialer-list dialer-group-num protocol protocol-name { permit | deny | list access-list-number }

• E.g 1: dialer-list 1 protocol ip permit

• E.g 2: Dialer-list 2 protocol ip list 101Access-list 101 deny tcp any any eq

www

Access-list 101 permit ip any any

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Configuring DDR Dialer InformationConfiguring DDR Dialer Information

• Step 1: PPP on DDR interfaceHome(config)# username Central

password ciscoHome(config)# interface bri0/0Home(config-if)# encapsulation pppHome(config-if)# ppp authenticationchapHome(config-if)# ip address 10.1.0.1255.255.255.0

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Configuring DDR Dialer Information(cont)Configuring DDR Dialer Information(cont)

• Step 2:– A dialer list specifying the interesting traffic for

this DDR interface needs to be associated with the

DDR interface.– This is done using the dialer-group group-

number command:– Home(config-if)# dialer-group 1

– group-number specifies the number of the dialergroup to which the interface belongs.

– This number must match the dialer-list group-number .

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Configuring DDR Dialer Information(cont)Configuring DDR Dialer Information(cont)

• Step 3:– The correct dialing information for the remote DDR

interface needs to be specified. This is done usingthe dialer map command.

– The dialer map command maps the remoteprotocol address to a telephone number. Thiscommand is necessary to dial multiple sites.

– Router(config-if)# dialer map protocol next-hop-address [name hostname ] [ speed 56 | 64 ]

[broadcast ] dial-string – If dialing only one site, use an unconditional dialerstring command

– The dialer idle-timeout seconds command maybe used to specify the number of idle secondsbefore a call is disconnected

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Configuring Legacy DDR ExampleConfiguring Legacy DDR Example

Central

How do I get tosubnetwork 10.10.0.0?

Number to dial

Remote host nameUsed for PPP CHAP

Ip route 10.10.0.0 255.255.0.0 10.10.0.2

dialer-list 1 protocol ip permit

interface BRI0ip address 10.1.0.1 255.255.255.0encapsulation pppdialer idle-timeout 180dialer map ip 10.1.0.2 name Central 5552000dialer-group 1no fair-queueppp authentication chap

ISDNHome10.1.0.1

bri 05551000

bri 05552000

10.1.0.2 Subnets10.10.0.010.20.0.0

Task1

Task2

Task3

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Dialer ProfilesDialer Profiles

• Legacy DDR is limited because the configuration is applieddirectly to a physical interface.

• Since the IP address is applied directly to the interface, thenonly DDR interfaces configured in that specific subnet canestablish a DDR connection with that interface.

• Dialer profiles remove the configuration from the interfacereceiving or making calls and only bind the configuration to

the interface on a per-call basis.• Dialer profiles allow physical interfaces to dynamically take

on different characteristics based on incoming or outgoingcall requirements.

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Dialer ProfilesDialer Profiles

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Dialer Profile ElementsDialer Profile Elements

Dialer interface – A logicalentity that uses a per-destination dialer profileDialer pool –a group of one or more physicalinterfaces associated with adialer profile

Physicalinterfaces –Interfaces in a dialerpool are configuredfor encapsulationparameters and to

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Configuring Dialer ProfilesConfiguring Dialer Profiles

• Multiple dialer interfaces may be configuredon a router.• Each dialer interface is the complete

configuration for a destination.

• To configure the dialer interface, perform thefollowing tasks:

• Task 1:–

Configure one or more dialer interfaces with allthe basic DDR commands:• IP address• Encapsulation type and authentication• Idle-timer

• Dialer-group for interesting traffic

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Configuring Dialer Profiles(cont.)Configuring Dialer Profiles(cont.)

• Task2:– Configure a dialer string and dialer remote-name

to specify the remote router name and phone numberto dial it.

• Task 3– The dialer pool associates this logical interface with a

pool of physical interfaces.

• Task 4:– Configure the physical interfaces and assign them to a

dialer pool using the dialer pool-member command

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Configuring Dialer Profiles(cont.)Configuring Dialer Profiles(cont.)

• An physical interface can be assigned tomultiple dialer pools by using multiple dialerpool-member commands.

• If more than one physical interface exists inthe pool, use the priority option of thedialer pool-member command to set thepriority of the interface within a dialer pool.

• If multiple calls need to be placed and onlyone interface is available, then the dialer poolwith the highest priority is the one that dials

out.

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Verifying DDR ConfigurationVerifying DDR Configuration

• The show dialer interface [BRI] command– The message “Dialer state is data link layer up”

suggests that the dialer came up properly andinterface BRI 0/0:1 is bound to the profile dialer1.

• The show isdn active command displaysinformation about the current active ISDN calls.

• The show isdn status command displays

information about the three layers of the BRIinterface.– In this output, ISDN Layer 1 is active, ISDN Layer 2

is established with SPID1 and SPID2 validated, and

there is one active connection on Layer 3.

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Troubleshooting The DDR ConfigurationTroubleshooting The DDR Configuration

• debug isdn q921 • the seventh and eighth most significant

hexadecimal numbers in the “i =” field indicate thetype of Q.931 message:– 0x05 indicates a call setup message– 0x02 indicates a call proceeding message– 0x07 indicates a call connect message– 0x0F indicates a connect acknowledgment (ack)

message

• The debug isdn q931 command is useful forobserving call setup exchanges for both outgoingand incoming calls

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Troubleshooting The DDR Configuration (cont)Troubleshooting The DDR Configuration (cont)

• The debug dialer [events | packets] command is useful for troubleshooting DDRconnectivity.

• The debug dialer events command sends amessage to the console indicating when aDDR link has connected and what trafficcaused it to connect.

• If there is no debug output, then the router isnot aware of any interesting traffic. Anincorrectly configured dialer or access list

may be the cause.

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Troubleshooting The DDR Configuration (cont)Troubleshooting The DDR Configuration (cont)

• Use the isdn call interface command toforce the local router to attempt to dial intothe remote router.

• If the routers cannot communicate using thiscommand, then the lack of connectivity is anISDN problem, not a DDR problem

• The clear interface bri command clearscurrently established connections on theinterface and resets the interface with theISDN switch.

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Legacy DDR with multiple destinationsLegacy DDR with multiple destinations

• Specific call parameters must bedefined under three separate physicalinterfaces, each of them connected to aseparate line.

• This scenario might result in a waste of resources and money.

• A router with three dialup WANinterfaces would be needed, in additionto the cost of the three lines that might

be used for only a few minutes daily.

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Using Dialer Profiles with multiple destinationsUsing Dialer Profiles with multiple destinations

• A more efficient solution is amechanism called DDR withdialer profiles .

• With dialer profiles the physicalinterfaces are not locked into

permanent configurations.• Call parameters are on an as-

needed basis.

• When the call is finished, thephysical interface is freed of

the previous logicalconfiguration and is ready toservice another callingdestination using a differentdialing profile.

• More later…

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Using Dialer Profiles with multiple destinationsUsing Dialer Profiles with multiple destinations

With Dialer Profiles Without Dialer Profiles

With Dialer Profiles the interface is not locked into

a specific use with a permanent configuration.

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Dialer ProfilesDialer Profiles

• Dialer profiles remove the configuration from the interface receiving or makingcalls and only bind the configuration to the interface on a per-call basis.

• Dialer profiles allow physical interfaces to dynamically take on differentcharacteristics based on incoming or outgoing call requirements.

• Using dialer profiles, the following tasks may be performed:– Configure B channels of an ISDN interface with different IP subnets.– Use different encapsulations on the B channels of an ISDN interface.

– Set different DDR parameters for the B channels of an ISDN interface.

– Eliminate the waste of ISDN B channels by letting ISDN BRIs belong to multiple dialer pools.

Dialer ProfileDialer Profile

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Dialer ProfileDialer ProfileElementsElements

• A dialer profile consists of the following elements:• Dialer interface – A logical entity that uses a per-destination dialer profile.

• Dialer pool – Each dialer interface references a dialer pool, which is a groupof one or more physical interfaces associated with a dialer profile.

• Physical interfaces – Interfaces in a dialer pool are configured forencapsulation parameters and to identify the dialer pools to which theinterface belongs. PPP authentication, encapsulation type, and multilink PPPare all configured on the physical interface.

inter bri 0dialer pool-member 1

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The Dialer InterfaceThe Dialer Interface

• The dialer interface is a mechanism in which physical interfacesare not locked with permanent configurations, but the mechanismassumes call parameters on an as-needed basis.

• Using the dialer interface allows you to specify one set of dialermaps that can apply to multiple physical lines.

• The dialer interface is not a physical interface .• When a physical interface is being used for dialing, it inherits

the parameters configured for the dialer interface .

• Dialer interfaces provide flexibility through dialer profiles .

p

interface Dialer0ip address 21.1.1.1 255.0.0.0encapsulation lapb dce multidialer remote-name RU1

dialer idle-timeout 300dialer string 60036dialer-group 1dialer pool 1

interface Dialer1ip address 22.1.1.1 255.0.0.0encapsulation pppdialer remote-name RU2dialer string 60043dialer-group 1

ppp authentication chapdialer pool 1

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Dialer interfacesDialer interfaces

• Multiple dialer interfaces may be configured on a router.• Each dialer interface is the complete configuration for a destination. The

interface dialer command creates a dialer interface and entersinterface configuration mode.

• To configure the dialer interface, perform the following tasks:1. Configure one or more dialer interfaces with all the basic DDR commands:

– IP address– Encapsulation type and authentication

– Idle-timer– Dialer-group for interesting traffic

1. Configure a dialer string and dialer remote-name to specify the remoterouter name and phone number to dial it. The dialer pool associates thislogical interface with a pool of physical interfaces.

2. Configure the physical interfaces and assign them to a dialer pool using thedialer pool-member

command.

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Dialer pool-memberDialer pool-member

• An interface can be assigned to multiple dialer pools by using multipledialer pool-member commands.

• If more than one physical interface exists in the pool, use the priority option of the dialer pool-member command to set the priority of theinterface within a dialer pool.

• If multiple calls need to be placed and only one interface is available,then the dialer pool with the highest priority is the one that dials out.

dialer poo1 2

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i n t b r i 0s p i d s

e n c a p p

D i a l e r t o b e

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2D i a

E x

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No Dialer Map!

Before IOS12.0.(7)T, youmust configure

encapsulationoptions on bothphysical andlogicalinterfaces.

Dialer Profiles ConfigDialer Profiles Config

RTA(config)#interface

bri0/0RTA(config-if)# isdn spid1 51055512340001 5551234

RTA(config-if)# isdn spid2 51055512350001 5551235RTA(config-if)# encapsulation pppRTA(config-if)# ppp authentication chapRTA(config-if)# dialer pool-member 1

RTA(config)# interface dialer 0RTA(config-if)# dialer pool 1RTA(config-if)# ip address 10.1.1.1 255.255.255.0RTA(config-if)# encapsulation pppRTA(config-if)# ppp authentication chapRTA(config-if)# dialer-group 1RTA(config-if)# dialer remote-name RTBRTA(config-if)# dialer string 5554000RTA(config-if)# dialer string 5554001

Placing calls with dialerPlacing calls with dialer

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Placing calls with dialerPlacing calls with dialerprofilesprofiles

• If there is no dialer map,how does the router knowwhich dialer profile to use

when placing a call?

Placing calls with dialerPlacing calls with dialer

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Placing calls with dialerPlacing calls with dialerprofilesprofiles

• If Central2 receives interesting trafficdestined for the 10.0.0.0 network, it willcheck the routing table.

• The routing table indicates that the next-hopIP address for the 10.0.0.0 network is 1.1.1.2.

• “Of the three configured dialer profiles, onlyinterface Dialer1 is configured with an IPaddress, 1.1.1.1, which is in the same subnetas 1.1.1.2.” Not the complete story, next slide.

• Therefore, interface Dialer1 is bound tothe first available interface in dialerpool 1 and the call is made to 5551111.

Placing calls with dialerPlacing calls with dialer

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Placing calls with dialerPlacing calls with dialerprofilesprofiles

• The routing table finds 10.0.0.0/8which has an intermediate address of 1.1.1.2.

• The routing table needs to resolve thisto an exit interface.

• The routing table process looks up1.1.1.2 finding the 1.0.0.0/24 network.

• 1.0.0.0/24 has an exit interface of Dialer1.

• Interface dialer1 is used as the dialer.

Placing calls with dialerPlacing calls with dialer

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Placing calls with dialerPlacing calls with dialerprofilesprofiles

• The same process is repeated whenCentral2 receives interesting trafficdestined for 30.1.15.4.

• After checking the routing table,Central2 finds that the next hop to the30.0.0.0/8 network is 3.3.3.1.

• “Central2 then scans the configureddialer profiles. Central2 finds thatinterface Dialer3 is configured with anIP address on the same subnet as thenext hop.” Not the complete story.

• In this case, interface Dialer3 is boundto an interface in dialer pool 1, so that

the call can be made to 5553333.

Placing calls with dialerPlacing calls with dialer

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Placing calls with dialerPlacing calls with dialerprofilesprofiles

• The routing table finds 30.0.0.0/8which has an intermediate addressof 3.3.3.1.

• The routing table needs to resolvethis to an exit interface.

• The routing table process looks up3.3.3.1 finding the 3.0.0.0/24network.

• 3.0.0.0/24 has an exit interface of Dialer3.

• Interface dialer3 is used as the

dialer.

Receiving calls withReceiving calls with

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Receiving calls withReceiving calls withdialer profilesdialer profiles

• How does the routerknow which dialerprofile to use whenreceiving a call?

Receiving calls withReceiving calls with

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Receiving calls withReceiving calls withdialer profilesdialer profiles

•If an interface inCentral2 dialer pool 1receives a call, it canbind to any of the

three dialer profiles

Receiving calls withReceiving calls with RTB

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Receiving calls withReceiving calls withdialer profilesdialer profiles

• When RTB places a call to Central2, it

dials a phone number that establishesa call with the BRI0 dialing pool atCentral2.

• At this point, Central2 does not knowwhich dialer profile to bind to BRI0.

• Because RTB is using PPP with CHAP,Central2's BRI0 needs to support this

in order for the call to proceed.• That is why dialer pool members, or

physical interfaces, must havefeatures such as, encapsulation, PPPauthentication, and multilink PPP (MLP)already configured in order to use.

?

Receiving calls withReceiving calls with RTB

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Receiving calls withReceiving calls withdialer profilesdialer profiles

• As part of the PPP Link ControlProtocol (LCP) linkestablishment process, RTB

sends its username to Central2.• Central2 learns that a host

called RTB is calling in, andlooks for a dialer profile thatincludes the dialer remote-name RTB command.

• In this case, Central2 finds thatinterface Dialer2 is configuredwith the RTB hostname.

• Therefore, Central2 bindsinterface Dialer2 to BRI0 andthe call continues.

Receiving calls withReceiving calls with RTB

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Receiving calls withgdialer profilesdialer profiles

• While it is very common to configure dialer

profiles with PPP and CHAP, it is not required.• See curriculum for other options.

• To complete the call, the bind occurs and thephysical interface is configured for PPPencapsulation and authentication (CHAP andPAP).

• The call will be disconnected if the CHAP orPAP name presented does not match what isconfigured in the dialer remote-name command on the dialer profile that wasbound to the call.

Must matchincomingCHAPname.

Dialer Profile and an Incoming Call

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Dialer Profile and an Incoming Call

Dialer Profile and an Outgoing Call

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Dialer Profile and an Outgoing Call

As discussedearlier, it

actuallyresolves theaddress to theexit interface.

Dialer Profiles outgoingDialer Profiles - outgoing

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Dialer Profiles - outgoingDialer Profiles - outgoing

RTB(config)# interface dialer 0RTB(config-if)# ip address 10.1.1.2 255.255.255.0RTB(config-if)# dialer pool 1RTB(config-if)# encapsulation pppRTB(config-if)# ppp authentication chapRTB(config-if)# dialer remote-name RTA RTB(config-if)# dialer-group 5RTB(config-if)# dialer string 5551234RTB(config-if)# dialer string 5551235

RTB(config)# interface dialer 1RTB(config-if)# ip address 172.16.0.2 255.255.255.0RTB(config-if)# dialer pool 1RTB(config-if)# encapsulation ppp

RTB(config-if)# ppp authentication chapRTB(config-if)# ppp chap hostname JULIETRTB(config-if)# dialer remote-name ROMEO RTB(config-if)# dialer-group 5RTB(config-if)# dialer string 5555678RTB(config-if)# dialer string 5555679

Ping 10.1.1.1

Without a dialer map,which maps an IP to a

phone number (dialer string), how does therouter know which dialer interface to bind to theBRI?

Ping 10.1.1.1

Without a dialer map,which maps an IP to a

phone number (dialer string), how does therouter know which dialer interface to bind to theBRI?

Use interface dialer 0, it’son the same subnet!

Di l P filDi l P fil

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Dialer ProfilesDialer Profiles

Physical Interfaces• dialer pool-member pool-number priority

• When dialing out, if more than one interface is amember of the same dialer pool, the dialer interface willuse whichever interface has the lowest priority value(which is the highest priority) will be tried first.

inter bri 0

dialer pool-member 10 2 (the winner!)inter bri 1dialer pool-member 10 50

inter dialer 1dialer pool 10

S l C fiS l C fi

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Sample ConfigSample Config

enable password cisco

username RTB password 0cisco

isdn switch-type basic-ni

!

interface BRI0

no ip address

no ip directed-broadcast

encapsulation ppp

dialer pool-member 1

isdn switch-type basic-niisdn spid1 51055512340001

5551234

isdn spid2 510555123500015551235

ppp authentication chap

interface Dialer0ip address 10.1.1.1 255.255.255.0encapsulation pppdialer remote-name RTBdialer string 5554000dialer string 5554001dialer load-threshold 1 either

dialer pool 1

dialer-group 1ppp authentication chapppp multilink

!ip route 192.168.1.0 255.255.255.010.1.1.2dialer-list 1 protocol ip permit

Di l P filDi l P fil

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Dialer ProfilesDialer Profiles

NOTE: Prior to IOS 12.0(7)T

Because the binding of the physical interface to the dialerinterface only happens after the incoming call has been

identified, you must define the layer 2 encapsulation andauthentication on both the physical interface and the dialerinterface.

The layer 2 encapsulations and authentications must match.

IOS 12.0(7)T introduces Dynamic Multiple Encapsulationsfeature, only the layer 2 encapsulation and authenticationon the dialer interface is used.

Go to Cisco’s web site for more information on this feature.

V if i DDR fi tiV if i g DDR fig ti

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Verifying DDR configurationVerifying DDR configuration

• The show dialer interface [BRI] command displays information inthe same format as the legacy DDR statistics on incoming and outgoingcalls.

• The message “Dialer state is data link layer up” suggests that the dialercame up properly and interface BRI 0/0:1 is bound to the profile dialer1.

V if i g DDR fig tiVerif ing DDR config ration

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Verifying DDR configurationVerifying DDR configuration

• The show isdn active command displaysinformation about the current active ISDN calls.• In this output, the ISDN call is outgoing to a remote

router named Seattle.

V if i g DDR fig tiVerifying DDR configuration

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Verifying DDR configurationVerifying DDR configuration

• The show isdn status command displays information about the threelayers of the BRI interface.

• In this output, ISDN Layer 1 is active, ISDN Layer 2 is established with SPID1and SPID2 validated, and there is one active connection on Layer 3.

Sho interface bri and spoofingShow interface bri and spoofing

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Show interface bri and spoofingShow interface bri and spoofing

• DDR interfaces must spoof, that is, pretend to be “up andup,” so that they stay in the routing table.

• By default, a router removes any routes point to downinterfaces from its routing table

phoenix# show inter bri 0BRI0 is up , line protocol is up (spoofing)

Hardware is PQUICC BRI with U interfaceInternet address is 10.1.1.2/24MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255Encapsulation PPP, loopback not set. . . . .

Troubleshooting the DDR configurationTroubleshooting the DDR configuration

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Troubleshooting the DDR configurationTroubleshooting the DDR configuration

• The debug isdn q921 command is useful forviewing Layer 2 ISDNcall setup exchanges

• 0x05 indicates a callsetup message

• 0x02 indicates a callproceeding message

• 0x07 indicates a callconnect message

• 0x0F indicates aconnectacknowledgment (ack)message

Troubleshooting the DDR configurationTroubleshooting the DDR configuration

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Troubleshooting the DDR configurationTroubleshooting the DDR configuration

• The debug isdn q931 command is useful forobserving call setup exchanges for both

outgoing and incoming calls.

Troubleshooting the DDR configurationTroubleshooting the DDR configuration

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Troubleshooting the DDR configurationTroubleshooting the DDR configuration

• The debug isdn q931 command is useful for observing call setupexchanges for both outgoing and incoming calls.

Troubleshooting the DDR configurationTroubleshooting the DDR configuration

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Troubleshooting the DDR configurationTroubleshooting the DDR configuration

• The debug dialer [events | packets] command is useful fortroubleshooting DDR connectivity.• The debug dialer events command sends a message to the

console indicating when a DDR link has connected and whattraffic caused it to connect.

Troubleshooting the DDR configurationTroubleshooting the DDR configuration

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Troubleshooting the DDR configurationTroubleshooting the DDR configuration

•If a router is not connecting when it should, then it is possible that anISDN problem is the cause, as opposed to a DDR problem.

• The remote router may be incorrectly configured, or there could be aproblem with the ISDN carrier network.

• Use the isdn call interface command to force the local router toattempt to dial into the remote router.

• The clear interface bri command clears currently establishedconnections on the interface and resets the interface with the ISDNswitch.

• This command forces the router to renegotiate its SPIDs with theISDN switch, and is sometimes necessary after making changes tothe isdn spid1 and isdn spid2 commands on an interface.

SummarySummary

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SummarySummary

• ISDN carries data, voice, and video• ISDN uses standards for addressing,

concepts, and signaling• ISDN uses the physical and data-link layers

• Interfaces and reference points for ISDN• Router configuration for ISDN• Which traffic is allowed when configuring DDR

• Static routes for DDR• The correct encapsulation type for DDR• Access lists affecting DDR traffic

• Dialer interfaces

Q&AQ&A

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Q&AQ&A