Dialer Profiles

1
Dialer Profiles

• The dial-on-demand routing (DDR) configurations
  introduced in previous chapters are examples of
  what Cisco terms "legacy DDR". A legacy is
  something received from the past. In this case,
  legacy DDR refers to the "old" way of configuring
  DDR, which is characterized by the application of
  dialer commands directly on the physical
  interface (BRI0, Async0, etc.), or by the use of
  rotary groups.

2
Dialer Profiles

• This chapter examines the weaknesses of legacy
  DDR (including rotary groups) and details a
  newer, alternate method of DDR configuration
  using dialer profiles. DDR with dialer profiles
  allows for the most flexible and efficient dial
  configurations.

3
Legacy DDR

• Legacy DDR is powerful and comprehensive. It
  supports Frame Relay, the International
  Organization for Standardization Connectionless
  Network Service (ISO CLNS), the Link Access
  Procedure Balanced (LAPB) protocol, snapshot
  routing, and all routed protocols that are
  supported on Cisco routers. However, legacy DDR's
  limitations can adversely affect growth.

4
Legacy DDR

• Legacy DDR is based on a static binding between
  the per-destination call specification and the
  physical interface configuration.
• The problem with this method is that legacy DDR
  locks a physical interface into one
  configuration. For example, DDR BRI0 can have
  only one Internet Protocol (IP) address, one
  encapsulation type, and one set of dialer timers.

5
Legacy DDR

• Legacy DDR configuration uses dialer map
  statements, which are convenient when one
  physical interface is responsible for calling one
  destination.
• The dialer map command can also be used if your
  router calls multiple destinations that all use
  the same communication parameters.

6
Legacy DDR with Multiple Connections

• Many separate dialer map statements can be
  configured on the same interface.
• What if your router is responsible for reaching
  three separate locations that use different
  communication parameters? Suppose that one
  location requires Password Authentication
  Protocol (PAP) authentication when another is
  doing Challenge Handshake Authentication Protocol
  (CHAP) authentication.

7
Legacy DDR with Multiple Connections

• One location might require an Integrated Services
  Digital Network (ISDN) speed of 56 kbps, whereas
  the other destinations communicate at 64 kbps.

8
Legacy DDR with Multiple Connections

• Answer Specific call parameters must be defined
  under three separate physical interfaces, each of
  them connected to a separate line.
• The previous scenario might result in a waste of
  resources and money. You would have to procure a
  router with three dial-up WAN interfaces and you
  would have to pay for three lines that might be
  used for only a few minutes daily.

9
Legacy DDR with Multiple Connections

• A more efficient solution might be a mechanism in
  which physical interfaces are not locked in to
  permanent configurations. Instead, this mechanism
  assumes call parameters on an as-needed basis.

10
Legacy DDR with Multiple Connections

• When the call is finished, the same interface is
  freed of the previous configuration and is ready
  to service another calling destination. This
  method is called DDR with dialer profiles, and is
  discussed in the section "Dialer Profiles," later
  in this chapter.

11
Legacy DDR with Multiple Connections

• Consider another scenario. What if you have
  multiple physical interfaces that all need to be
  configured with the exact same communication
  parameters? For example, you may have eight
  asynchronous interfaces that each will answer
  calls using the same IP address, same
  encapsulation, and same dialer configuration
  commands. The solution is to use dialer rotary
  groups.

12
Rotary Groups

• Dialer rotary groups allow you to apply a single
  interface configuration to a set of physical
  interfaces. Dialer rotary groups are useful in
  environments that have multiple callers and
  calling destinations.

13
Rotary Groups

• You define a dialer rotary group by specifying a
  "dialer interface." The dialer interface is not a
  physical interface. It is an entity that allows
  you to propagate an interface configuration to
  multiple interfaces. After you define the dialer
  interface by a number, such as interface Dialer
  0, you can then configure parameters for that
  interface.

14
Rotary Groups

• Finally, physical interfaces are assigned to the
  dialer rotary group. Physical interfaces inherit
  the dialer interface configuration parameters.
• Ex. Interface BRI0 Dialer Rotary Group 0.

15
Using Rotary Groups

• The telephone company also has rotary groups,
  called hunt groups, which allow you to dial one
  phone number and be connected to one of several
  different phone numbers.
• In other words, a hunt group is a series of
  telephone lines that are programmed so that as
  incoming calls arrive the first available line is
  used. If the first line is busy the second line
  is tried, and then the third line is tried, and
  so on, until a free line is found.

16
Using Rotary Groups

• Most ISPs use a hunt group for their customer
  access numbers. This is why several customers of
  an ISP can dial the same number and connect at
  the same time.
• Rotary groups can be used for outgoing calls as
  well. After a dialer interface configuration is
  propagated to a set of physical interfaces, you
  can use those interfaces to place calls using
  standard DDR criteria.

17
Using Rotary Groups

• When many destinations are configured, any of the
  physical interfaces in a rotary group can be used
  for outgoing calls. When traffic arrives to be
  routed using DDR, an interface from the rotary
  group is dialed. When traffic for a different
  host arrives, another interface is dialed.
• Using the dialer interface allows you to specify
  one set of dialer maps that can apply to multiple
  physical lines.

18
Configuring Rotary Groups

• The interface dialer command in global
  configuration mode creates a dialer rotary group
  
• Router(config)interface dialer group-number
• You can assign a physical interface to a dialer
  rotary group using the following command
• Router(config-if)dialer rotary-group
  group-number

19
Configuring Rotary Groups

• If you want to use the same logical configuration
  on three of the asynchronous lines of a Cisco
  2511 access server, you can use this as an
  example
• The interface dialer 1 command creates the
  logical interface configuration that will be
  shared among the members of the rotary group.
  Since this interface is numbered "1," a physical
  line must belong to dialer rotary-group 1 in
  order to use this configuration.

20
(No Transcript)
21
Configuring Rotary Groups

• Notice that the secondary parameter is used with
  the ip address command to assign additional
  logical addresses. In the figure, interface
  Dialer1 is configured so that members of dialer
  rotary-group 1 can assume one of three IP
  addresses depending on which dialer map statement
  is used.

22
Configuring ISDN for Dialer Rotary Groups

• A physical interface can belong to only one
  dialer rotary group. However, the dialer
  rotary-group command can be used with any dial-up
  interface, async, BRI, PRI, and serial.
• The shaded commands in the next graphic assign
  all the BRIs to dialer rotary-group 2 so that the
  BRIs answer calls made to the same phone number
  as part of the hunt group.

23
(No Transcript)
24
Asynchronous Interface Groups

• A dialer rotary group propagates a single
  configuration to multiple interfaces. Similarly,
  the interface group-async command configures a
  "group" interface.
• You can configure the group interface to include
  multiple asynchronous interfaces as members. All
  members share the group configuration.

25
(No Transcript)
26
Asynchronous Interface Groups

• You assign interfaces to a group using the
  group-range command. In the figure, asynchronous
  interfaces 1 through 8 are assigned to the group
  with the command group-range 1 8. After assigning
  asynchronous interfaces to a group, you cannot
  configure these interfaces separately.

27
Dialer Profiles

• The newer way of configuring DDR is called DDR
  with dialer profiles. Dialer profiles separate
  the logical configuration from the interface that
  receives or makes calls.
• Profiles can define encapsulation, access control
  lists (ACLs), as well as turn features on or off.

28
(No Transcript)
29
Dialer Profiles

• With dialer profiles, the logical and physical
  configurations are dynamically bound to each
  other on a per-call basis, allowing physical
  interfaces to take on different characteristics
  based on incoming or outgoing calls.

30
Dialer Profiles

• Like dialer rotary groups, dialer profiles use
  the dialer interface to separate the logical
  configuration (i.e., an IP address, Layer 2
  encapsulation, and dialer parameters) from the
  physical interface that places or receives calls.
  
• However, unlike a dialer rotary group, a physical
  interface can be used by multiple dialer
  interfaces.

31
(No Transcript)
32
Dialer Profiles

• Essentially, each dialer interface is a dialer
  profile that can be bound to any member of the
  dialer pool. You can configure a dialer profile
  for each remote with whom you will be
  establishing a call.

33
Dialer Profiles

• When the access server needs to place a call, it
  looks for the appropriate dialer profile. Once it
  identifies the correct profile, the access server
  attempts to find an available physical interface
  that belongs to the appropriate dialer pool. If a
  physical interface is available, the access
  server temporarily binds the dialer profile to
  that interface and makes the call.

34
(No Transcript)
35
Configuring Dialer Profiles

• When you are using dialer profiles, the IOS will
  not allow you to configure the dialer interface
  with a dialer map command. Recall that dialer map
  statements are used with legacy DDR so that a
  single interface can call, or receive calls, from
  multiple hosts. The purpose of the dialer map
  command is to map the phone number to an IP
  address, and to identify the remote host's name
  for the purposes of CHAP or PAP authentication.

36
Configuring Dialer Profiles

• With dialer profiles, you typically configure a
  profile for each remote host to which the router
  will connect, so connecting to multiple
  destinations is not an issue. Instead of
  specifying the phone number using a dialer map
  command, you use the dialer string command with
  dialer profiles.

37
Configuring Dialer Profiles

• The dialer string command specifies the phone
  number to dial when placing a call from an
  interface to a specific destination. The syntax
  is as follows
• Router(config-if)dialer string dial-string.

38
Configuring Dialer Profiles

• You will also need some way to specify the
  hostname of the remote system in order for PPP
  authentication to work. Use the dialer
  remote-name command to specify the authentication
  name of the host
• Router(config-if)dialer remote-name username.

39
Configuring Dialer Profiles

• The first profile, interface Dialer0, is a
  profile for calling, or receiving calls from, a
  router called RTX.
• The second profile, interface Dailer1, has no
  dialer string configured. This profile will be
  used to receive incoming calls only.

40
Configuring Dialer Profiles

• Finally, the third profile, interface Dialer2, is
  configured so that the router can either make or
  receive a call to RTY. Two dialer string commands
  specify two different phone numbers that can be
  used to connect with this host.

41
Configuring Dialer Profiles

• All three of these dialer profiles are configured
  to use any interfaces in dialer pool 1. A dialer
  pool is a collection of dial interfaces that can
  be used by a dialer profile. In this case, BRI0,
  BRI1, and BRI2 belong to dialer pool 1.

42
Configuring Dialer Profiles

• The main difference between a dialer rotary group
  and a dialer profile is that a physical interface
  participates in only one rotary group. With a
  dialer profile, a physical interface can belong
  to many different pools.

43
Configuring Dialer Profiles

• You configure both dialer rotary groups and
  dialer profiles by creating a dialer interface
  (i.e., interface Dialer0, interface Dialer1,
  etc.). If you use the dialer pool command to
  configure a dialer interface, you create a dialer
  profile. Remember, when you use the dialer pool
  command, you cannot use dialer map commands. You
  must use dialer string and dialer remote-name
  instead.

44
(No Transcript)
45
(No Transcript)
46
(No Transcript)