ISDN Dial-on-Demand Routing using Dialer Profiles.

1
ISDN Dial-on-Demand Routingusing 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

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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.

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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.

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Dialer Profile Components cont

• 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.

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Relationship between Dialer Pools, Dialer
Interfaces and Physical Interfaces.
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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.

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Advantages continued

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

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Legacy DDR Limitations

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

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Dialer Interfaces Illustrated
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Dialer Profile Bindings

1. An incoming packet arrives on the router
   interface, a routing table look-up indicates its
   destination address over a dialer interface.
2. 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.
3. 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.
4. 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.

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Dialer Profile Bindings cont

• 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.

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Dialer Interfaces, Dialer Pools and Physical
Interfaces
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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.

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Dialer Interface Configuration cont

• 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