ISDN Dial-on-Demand Routing using Dialer Profiles. Dial-on-Demand Routing (DDR) can be implemented using either Legacy DDR or Dialer Profiles. This presentation describes the advantages of the Dialer Profile method Dial-on-Demand Routing (DDR) can be implemented using either Legacy DDR or Dialer Profiles.

Dialer Profile Overview Dialer Profiles separate logical configurations from the physical interfaces that make or receive calls. Dialer Profiles allow physical and logical configurations to be bound together dynamically on a per call basis. Dialer Profiles can define encapsulations, access control lists, idle and fast-idle timers and bandwidth requirements on a per call basis. With Legacy DDR implementation each point-to-point connection is served by a physical interface that has fixed parameters set on all connections.

Dialer Profile Components Dialer Interfaces – Logical entities that use a per-destination dialer profile. Any number of dialer interfaces can be created in a router. All configuration settings specific to the destination go in the dialer interface configuration. Dialer Pool – Each interface references a dialer pool, which is a group of physical interfaces (ISDN BRI or PRI, asynchronous-modem and synchronous serial) associated with a dialer profile. Dialer Interfaces – Logical entities that use a per-destination dialer profile. Any number of dialer interfaces can be created in a router. All configuration settings specific to the destination go in the dialer interface configuration. Dialer Pool – Each interface references a dialer pool, which is a group of physical interfaces (ISDN BRI or PRI, asynchronous-modem and synchronous serial) associated with a dialer profile.

Dialer Profile Components con’t Physical Interfaces – Interfaces in a dialer pool are configured for encapsulation parameters. The interfaces are also configured to identify the dialer pools to which the interface belong. Dialer profiles support PPP and HDLC encapsulations. Dialer – Map Class – Supplies configuration parameters to dialer interfaces for example – ISDN speed, dialer timers. A map-class can be referenced from multiple dialer interfaces.

Relationship between Dialer Pools, Dialer Interfaces and Physical Interfaces.

Advantages of Dialer Profiles over Legacy DDR Dialer profiles allow for the creation of different configurations for the ISDN B channels of a PRI. Dialer Profiles allow BRIs to belong to multiple dialer pools. This eliminates wasting ISDN B channels. Different DDR parameters can be set for each B channel on an ISDN Interface. Multiple Destinations can be bridged to avoid split- horizon problems.

Advantages continued Remote routers or users can be controlled or customized through independent dialer profiles.

Legacy DDR Limitations There is one configured interface per ISDN interface. Before dialer profiles all ISDN B channels inherited the physical interface’s configuration. Before dialer profiles, one dialer map was required per dialer per protocol, thus making multi-protocol configurations very complex.

Dialer Interfaces Illustrated

Dialer Profile Bindings An incoming packet arrives on the router interface, a routing table look-up indicates its destination address over a dialer interface. The Cisco IOS software notes the dialer interface is a dialer profile. If there is not an existing connection for this profile, the pool that the dialer interface is associated with is identified. If there is an existing connection, the packet is queued to the physical interface and if the traffic is “interesting”, the idle-timer is reset. If there is no existing connection, the traffic is checked against the dialer-list to determine if it is interesting. If it is not the packet is dropped.

Dialer Profile Bindings con’t If the packet is interesting and there is no existing connection the Cisco IOS software searches for the physical interface that belongs to the dialer interface with the highest dialer pool priority. This is the interface that will be used for dialing. This interface is bound to the dialer interface, causing the physical interface to assume the configuration of the dialer interface. The IOS dials the dialer profile, and at this point the normal DDR steps occur.

Dialer Interfaces, Dialer Pools and Physical Interfaces

Dialer Interface Configuration RouterA(config)#interface Dialer 10 !Creates a dialer interface RouterA(config-if)#ip address 172.16.25.42 255.255.255.0 !IP address. For simplicity keep this address in the same network as the peer. RouterA(config-if)#encapsulation ppp RouterA(config-if)#dialer remote-name RouterB !Configure the central site router CHAP authentication name. RouterA(config-if)#dialer string 5554540 !Number for outbound call.

Dialer Interface Configuration con’t RouterA(config-if)#dialer pool 10 !Member of dialer pool 10 RouterA(config-if)#dialer-group 1 !Assign the dialer interface to a group. RouterA(config-if)#ppp authentication chap pap !Assigns CHAP/PAP authentication to the interface. RouterA(config-if)# ppp multilink !Enables multilink PPP on this interface. RouterA(config-if)#no shutdown