1. 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 may
help with understanding the transition from dialer maps to dialer
profiles.

2. Legacy DDR
Legacy DDR - configuring DDR by the application of dialer commands directly on the physical interface, BRI0, Async0, or by the use of rotary groups.
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.

3. 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 when connected.

4. Legacy DDR – dialer maps
Legacy DDR is 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.

5. Legacy DDR with multiple destinations
Specific call parameters must be defined under three separate physical interfaces, each of them connected to a separate line.
This scenario might result in a waste of resources 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.

6. Using Dialer Profiles with multiple destinations
A more efficient solution is a mechanism called DDR with dialer profiles.
With dialer profiles the physical interfaces are not locked into permanent configurations.
Call parameters are on an as-needed basis.
When the call is finished, the physical interface is freed of the previous logical configuration and is ready to service another calling destination using a different dialing profile.
More later…

7. 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.

8. Dialer Profiles
Dialer profiles remove the configuration from the interface receiving 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 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.

9. Dialer Profile Elements
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 group of one or more physical interfaces associated with a dialer profile.
Physical interfaces – Interfaces in a dialer pool are configured for encapsulation parameters and to identify the dialer pools to which the interface belongs. PPP authentication, encapsulation type, and multilink PPP are all configured on the physical interface.

10. inter bri 0
dialer pool-member 1
interface Dialer0
ip address
encapsulation ppp dce multi
dialer remote-name RU1
dialer idle-timeout 300
dialer string 60036
dialer-group 1
dialer pool 1
interface Dialer1
ip address
encapsulation ppp
dialer remote-name RU2
dialer string 60043
ppp authentication chap
The Dialer Interface
The dialer interface is a mechanism in which physical interfaces are not locked with permanent configurations, but the mechanism assumes call parameters on an as-needed basis.
Using the dialer interface allows you to specify one set of dialer maps 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.

11. 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 interface configuration mode.
To configure the dialer interface, perform the following tasks:
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
Configure a dialer string and dialer remote-name to specify the remote router name and phone number to dial it. The dialer pool associates this logical interface with a pool of physical interfaces.
Configure the physical interfaces and assign them to a dialer pool using the dialer pool-member command.

12. Dialer pool-member
dialer poo1 2
An interface can be assigned to multiple dialer pools by using multiple dialer 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 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 priority is the one that dials out.

13. Dialer Profiles Config
RTA(config)#interface bri0/0
RTA(config-if)#isdn spid
RTA(config-if)#isdn spid
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
RTA(config-if)#dialer-group 1
RTA(config-if)#dialer remote-name RTB
RTA(config-if)#dialer string
RTA(config-if)#dialer string
Before IOS 12.0.(7)T, you must configure encapsulation options on both physical and logical interfaces.
No Dialer Map!

14. Placing calls with dialer profiles
If there is no dialer map, how does the router know which dialer profile to use when placing a call?

15. Placing calls with dialer profiles
If Central2 receives interesting traffic destined for the network, it will check the routing table.
The routing table indicates that the next-hop IP address for the network is
Of the three configured dialer profiles, only interface Dialer1 is configured with an IP address, , which is in the same subnet as
Therefore, interface Dialer1 is bound to the first available interface in dialer pool 1 and the call is made to

16. Placing calls with dialer profiles
The same process is repeated when Central2 receives interesting traffic destined for
After checking the routing table, Central2 finds that the next hop to the /8 network is
Central2 then scans the configured dialer profiles. Central2 finds that interface Dialer3 is configured with an IP address on the same subnet as the next hop.
In this case, interface Dialer3 is bound to an interface in dialer pool 1, so that the call can be made to

17. Dialer Profile and an Incoming Call

18. Dialer Profile and an Outgoing Call

19. Dialer Profiles - outgoing
Use interface dialer 0, it’s on the same subnet!
RTB(config)#interface dialer 0
RTB(config-if)#ip address
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
RTB(config-if)#dialer string
RTB(config)#interface dialer 1
RTB(config-if)#ip address
RTB(config-if)#ppp chap hostname JULIET
RTB(config-if)#dialer remote-name ROMEO
RTB(config-if)#dialer string
RTB(config-if)#dialer string
Ping
Without a dialer map, which maps an IP to a phone number (dialer string), how does the router know which dialer interface to bind to the BRI?

20. Dialer Profiles Physical Interfaces
dialer pool-member pool-number priority
When dialing out, if more than one interface is a member of the same dialer 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 50
inter dialer 1
dialer pool 10

21. Sample Config interface Dialer0 ip address 10.1.1.1 255.255.255.0
encapsulation ppp
dialer remote-name RTB
dialer string
dialer string
dialer load-threshold 1 either
dialer pool 1
dialer-group 1
ppp authentication chap
ppp multilink !
dialer-list 1 protocol ip permit
(config)#
ip route
enable password cisco
username RTB password 0 cisco
isdn switch-type basic-ni !
interface BRI0
no ip address
no ip directed-broadcast
encapsulation ppp
dialer pool-member 1
isdn spid
isdn spid
ppp authentication chap

22. Verifying DDR configuration
The show dialer interface [BRI] command displays information in the same format as the legacy DDR statistics on incoming and outgoing calls.
The message “Dialer state is data link layer up” suggests that the dialer came up properly and interface BRI 0/0:1 is bound to the profile dialer1.

23. Verifying DDR configuration
The show isdn active command displays information about the current active ISDN calls.
In this output, the ISDN call is outgoing to a remote router named Seattle.

24. Verifying DDR configuration
The show isdn status command displays information about the three layers of the BRI interface.
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.

25. Show interface bri and spoofing
DDR interfaces must spoof, that is, pretend to be “up and up,” 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 is up (spoofing)
Hardware is PQUICC BRI with U interface
Internet address is /24
MTU 1500 bytes, BW 64 Kbit, DLY usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, loopback not set

26. Troubleshooting the DDR configuration
The debug isdn q921 command is useful for viewing Layer 2 ISDN call setup exchanges
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

27. Troubleshooting the DDR configuration
The debug dialer [events | packets] command is useful for troubleshooting DDR connectivity.
The debug dialer events command sends a message to the console indicating when a DDR link has connected and what traffic caused it to connect.

28. Troubleshooting the DDR configuration
If a router is not connecting when it should, then it is possible that an ISDN problem is the cause, as opposed to a DDR problem.
The remote router may be incorrectly configured, or there could be a problem with the ISDN carrier network.
Use the isdn call interface command to force the local router to attempt to dial into the remote router.
The clear interface bri command clears currently established connections on the interface and resets the interface with the ISDN switch.
This command forces the router to renegotiate its SPIDs with the ISDN switch, and is sometimes necessary after making changes to the isdn spid1 and isdn spid2 commands on an interface.

29. Ch. 4 – ISDN and DDR
CCNA 4 version 3.0