Dialer rotary groups
simplify the configuration of physical interfaces by allowing you to
apply a single logical interface configuration to a set of physical
interfaces .
The single
logical interface is a dialer rotary group, which is defined by
specifying a dialer interface. Physical interfaces are assigned to
the dialer rotary group and inherit all the dialer interface
configuration parameters. When many destinations are configured, any
of the physical interfaces in a rotary group can be used for
outgoing calls.
To configure a rotary group,
you place each Basic Rate Interface (BRI) interface in a rotary group. In Figure ,
all the BRIs are assigned to dialer rotary-group 1. All these
BRI lines are also set in a hunt group. A hunt group is a
series of telephone lines that are programmed so that as incoming
calls arrive, 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. This way, an incoming call should not end up with a busy
signal.
You may still have to perform some of
the configuration on the physical interface rather than at the
dialer rotary interface. For example, if you connect to a switch
that requires service profile identifiers (SPIDs), you have to enter each of the SPIDs separately
at each of the physical BRI interfaces. The rest of the interface
configuration is done on the interface dialer 1, the new
rotary you created.
If you install multiple BRIs or
(Primary Rate Interfaces (PRIs)
to service remote users, request one phone number from the service
provider. You then assign all the interfaces to one rotary group,
or hunt group, so that you need to dial only one number for either
configuration. Using one number requires only one set of dialer-map
statements on the remote routers instead of multiple statements, a
scenario that also makes configuration and debugging much easier and less complicated.
The interface dialer command
in global configuration mode creates a dialer rotary group:
Router(config)#interface
dialer group-number
Then, you use the dialer
rotary-group command in interface (BRI,
async, and so on)
configuration mode to include that interface in the specified rotary
group, as shown in the syntax that follows. You have to use this
command on each interface that you wish to include in the rotary
group.
Router(config-if)#dialer
rotary-group group-number
The syntax for the interface
dialer and dialer rotary-group commands are explained in
Table .
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