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Dialer Profiles Some of this can be difficult to understand at first. The examples at the end of this section will help you understand

dialer profiles. Some information from CCNP 2 has been added to help clarify

dialer profiles and to provide more examples.

In CCNP 2 Rotary Groups (legacy DDR) is discussed which mayhelp with understanding the transition from dialer maps to dialer

profiles.

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Legacy DDR

Legacy DDR- configuring DDR by the application of dialer commands

directly on the physical interface, BRI0, Async0, or by the use of rotarygroups.

Legacy DDR is powerful and comprehensive. However, the limitations of legacy DDR can inhibit scalability. For instance, legacy DDR is based on static binding of a physical

interface to one per-destination call specification.

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Legacy DDR with a single destination

For example, DDR BRI0 can have only one Internet Protocol (IP)address, one encapsulation type, and one set of dialer timers.

Legacy DDR configuration uses dialer map statements. Dialer map statements are convenient when one physical interface is

responsible for calling one destination.

BRI can only dial a host named RTB, and can only use Point-to-Point

Protocol (PPP) with a dialer idle-timeout of 30 seconds whenconnected.

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Legacy DDR dialer maps

Legacy DDRis limited because the configuration is applied directly to

a physical interface. Since the IP address is applied directly to the interface, then only DDR

interfaces configured in that specific subnet can establish a DDR

connection with that interface.

This means that there is a one-to-one correspondence between the

two DDR interfaces at each end of the link.

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Legacy DDR with multiple destinations

Specific call parameters must be definedunder three separate physical interfaces,

each of them connected to a separate

line.

This scenario might result in a waste ofresources and money. A router with three dialup WAN interfaces

would be needed, in addition to 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

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 Profiles

Dialer profiles remove the configuration from the interface receiving ormaking calls and only bind the configuration to the interface on a per-callbasis.

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 ISDNinterface.

Eliminate the waste of ISDN B channels by letting ISDN BRIs belong

to multiple dialer pools.

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Dialer Profile

Elements

A dialer profile consists of the following elements: Dialer interfaceA logical entity that uses a per-destination dialer

profile.

Dialer poolEach dialer interface references a dialer pool, whichis a group of one or more physical interfaces associated with adialer profile.

Physical interfacesInterfaces in a dialer pool are configured forencapsulation parameters and to identify the dialer pools to whichthe interface belongs. PPP authentication, encapsulation type, and

multilink PPP are all configured on the physical interface.

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The Dialer Interface

The dialer interfaceis a mechanism in which physical interfaces are notlocked with permanent configurations, but the mechanism assumes callparameters on an as-needed basis.

Using the dialer interface allows you to specify one set of dialer maps thatcan apply to multiple physical lines.

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

parametersconfigured for the dialer interface.

Dialer interfaces provide flexibility through dialer profiles.

inter bri 0

dialer pool-member 1

interface Dialer0

ip address 21.1.1.1 255.0.0.0

encapsulation ppp dce multi

dialer remote-name RU1

dialer idle-timeout 300dialer string 60036

dialer-group 1

dialer pool 1

interface Dialer1

ip address 22.1.1.1 255.0.0.0

encapsulation ppp

dialer remote-name RU2dialer string 60043

dialer-group 1

ppp authentication chap

dialer pool 1

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Dialer 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 enters interfaceconfiguration 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

2. Configure a dialer stringand dialer remote-nameto specify theremote router name and phone number to dial it. The dialer poolassociates this logical interface with a pool of physical interfaces.

3. Configure the physical interfaces and assign them to a dialer pool using thedialer pool-membercommand.

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Dialer pool-member

An interface can be assigned to multiple dialer pools by using multipledialer pool-membercommands.

If more than one physical interface exists in the pool, use thepriorityoption of the dialer pool-membercommand to set the

priority of the interface within a dialer pool.

If multiple calls need to be placed and only one interface is available,

then the dialer pool with the highest priorityis the one that dials out.

dialer poo1 2

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No Dialer Map!

Before IOS

12.0.(7)T, you

must configure

encapsulationoptions on both

physical and

logical

interfaces.

Dialer Profiles Config

RTA(config)#interfacebri0/0

RTA(config-if)#isdn spid1 51055512340001 5551234

RTA(config-if)#isdn spid2 51055512350001 5551235

RTA(config-if)#encapsulation ppp

RTA(config-if)#ppp authentication chap

RTA(config-if)#dialer pool-member 1

RTA(config)#interface dialer 0

RTA(config-if)#dialer pool 1

RTA(config-if)#ip address 10.1.1.1 255.255.255.0

RTA(config-if)#encapsulation ppp

RTA(config-if)#ppp authentication chap

RTA(config-if)#dialer-group 1

RTA(config-if)#dialer remote-name RTB

RTA(config-if)#dialer string 5554000

RTA(config-if)#dialer string 5554001

Pl i ll ith di l

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Placing calls with dialer

profiles

If there is no dialer map,

how does the router knowwhich dialer profile to use

when placing a call?

Pl i ll ith di l

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profiles

If Central2 receives interesting trafficdestined for the 10.0.0.0 network, itwill check the routing table.

The routing table indicates that thenext-hop IP address for the 10.0.0.0network is 1.1.1.2.

Of the three configured dialer profiles,only interface Dialer1 is configuredwith an IP address, 1.1.1.1, which is inthe same subnet as 1.1.1.2.

Therefore, interface Dialer1 is boundto the first available interface indialer pool 1and the call is made to

5551111.

Pl i ll ith di l

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profiles

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.

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

the call can be made to 5553333.

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int bri 0

spids

encap ppp

ppp authen chap



interface dialer 1

dialer remote-name BranchA

ip address 172.16.1.1 /24

enacp ppp ppp authen chap

ppp multilink

dialer pool 10

Cisco RouterIncoming Call:Process for binding a dialer

interface to a physcial interface

BranchA

1

2

3

3

4

1.Incoming PPP connection from BranchA

2.Router performs chap authenticaion with BranchA

3.Router looks at dialer interfaces to see if any of them are

configured with remote-name BranchA4.Dialer interface 1 in bound with physical interface bri0

Dialer Profile and an Incoming Call

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int bri 0

spids

encap ppp

ppp authen chap dialer pool-member 10


interface dialer 1

dialer remote-name BranchA

ip address 172.16.1.1 /24 enacp ppp

ppp authen chap

ppp multilink

dialer pool 10 dialer string 5559999

Cisco RouterOutgoing Call:

Process for binding a dialerinterface to a physcial interface

BranchA

6

7

1

4

1.Do a routing table lookup for 192.168.1.0

2. Find dialer that has an interface on the same subnet as the

next-hop ip address.

3. Find a physical interface which is in the same dialer pool. If

more than one physcial interface exits, use the priority field inthe dialer pool-memeber statement.

4.Dialer interface is bound with a physical interface that is

participating in the same dialer pool.

5.Use dialer string for outgoing phone number

6.Connection is made

7.Authentication is checked.

ip route 192.168.1.0 255.255.255.0 172.16.1.2

5

2

192.168.1.0

172.16.1.2/24 3

Dialer Profile and an Outgoing Call

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Dialer Profiles - outgoing

RTB(config)#interface dialer 0

RTB(config-if)#ip address 10.1.1.2 255.255.255.0

RTB(config-if)#dialer pool 1

RTB(config-if)#encapsulation ppp

RTB(config-if)#ppp authentication chap

RTB(config-if)#dialer remote-name RTA

RTB(config-if)#dialer-group 5

RTB(config-if)#dialer string 5551234


RTB(config)#interface dialer 1

RTB(config-if)#ip address 172.16.0.2 255.255.255.0

RTB(config-if)#dialer pool 1

RTB(config-if)#encapsulation ppp

RTB(config-if)#ppp authentication chap

RTB(config-if)#ppp chap hostname JULIET

RTB(config-if)#dialer remote-name ROMEO

RTB(config-if)#dialer-group 5



Ping 10.1.1.1

Without a dialer map,

which maps an IP to a

phone number (dialerstring), how does the

router know which dialer

interface to bind to the

BRI?

Use interface dialer 0, its

on the same subnet!

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Dialer Profiles

Physical Interfaces

dialer pool-memberpool-number priority

When dialing out, if more than one interface is a member of the samedialer pool, the dialer interface will use 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 1

dialer pool-member 10 50inter dialer 1

dialer pool 10

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Sample Config

enable password cisco

username RTB password 0 cisco

isdn switch-type basic-ni

!

interface BRI0

no ip address

no ip directed-broadcast

encapsulation ppp


isdn switch-type basic-ni

isdn spid1 51055512340001

5551234

isdn spid2 510555123500015551235

ppp authentication chap

interface Dialer0

ip address 10.1.1.1 255.255.255.0encapsulation ppp

dialer remote-name RTB

dialer string 5554000

dialer string 5554001

dialer load-threshold 1 either

dialer pool 1

dialer-group 1ppp authentication chap

ppp multilink

!

dialer-list 1 protocol ip permit

(config)#

ip route 192.168.1.0 255.255.255.0

10.1.1.2

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Verifying DDR configuration

The show dialer interface [BRI]command displaysinformation in the same format as the legacy DDR statistics onincoming and outgoing calls.

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 profiledialer1.

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The show isdn activecommand displays information about the

current active ISDN calls. In this output, the ISDN call is outgoing to a remote router named

Seattle.

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The show isdn statuscommand displays information about thethree layers of the BRI interface.

In this output, ISDN Layer 1 is active, ISDN Layer 2 is established withSPID1 and SPID2 validated, and there is one active connection on

Layer 3.

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Show 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 down

interfaces from its routing table

phoenix#show inter bri 0

BRI0 is up, line protocol isup(spoofing)

Hardware is PQUICC BRI with U interface

Internet address is 10.1.1.2/24

MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, loopback not set. . . . .

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Troubleshooting the DDR configuration

The debug isdnq921command isuseful for viewing

Layer 2 ISDN call

setup exchanges

0x05 indicates a callsetup message

0x02 indicates a callproceeding message

0x07 indicates a callconnect message

0x0F indicates aconnect

acknowledgment

(ack) message

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The debug dialer [events | packets]command is useful fortroubleshooting DDR connectivity.

The debug dialer eventscommand sends a message to theconsole indicating when a DDR link has connected and what trafficcaused it to connect.

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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 interfacecommand to force the local router toattempt to dial into the remote router.

The clear interface bricommand clears currently establishedconnections on the interface and resets the interface with the ISDNswitch.

This command forces the router to renegotiate its SPIDs with the ISDNswitch, and is sometimes necessary after making changes to the isdnspid1and isdn spid2commands on an interface.

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Ch. 4

ISDN and DDR

CCNA 4 version 3.0

isdn_ii

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