To specify an ISDN PRI group on a channelized T1 or E1 controller, and to release the ISDN PRI signaling time slot, use the
pri-group timeslots command in controller configuration mode. To remove or change the ISDN PRI configuration, use the no form of this command.
pri-group timeslots timeslot-range [nfas_d {backup nfas_int number nfas_group number [service mgcp] | none nfas_int number nfas_group number [service mgcp] | primary nfas_int number nfas_group number [iua as-name | rlm-group number | service mgcp]} | service mgcp] [voice-dsp]
no pri-group timeslots timeslot-range [nfas_d {backup nfas_int number nfas_group number [service mgcp] | none nfas_int number nfas_group number [service mgcp] | primary nfas_int number nfas_group number [iua as-name | rlm-group number | service mgcp]} | service mgcp] [voice-dsp]
Syntax Description
timeslot-range
|
A value or range of values for time slots on a T1 or E1 controller that consists of an ISDN PRI group. Use a hyphen to indicate
a range.
Note
|
Groups of time slot ranges separated by commas (1-4,8-23 for example) are also accepted.
|
|
nfas_d
|
(Optional) Configures the operation of the ISDN PRI D channel.
|
backup
|
The D-channel time slot is used as the Non-Facility Associated Signaling (NFAS) D backup.
|
service
mgcp
|
(Optional) Configures the service type as Media Gateway Control Protocol (MGCP) service.
|
none
|
The D-channel time slot is used as an additional B channel.
|
primary
|
The D-channel time slot is used as the NFAS D primary.
|
nfas_int
number
|
Specifies the provisioned NFAS interface as a value. The NFAS interface range is from 0 to 44.
|
nfas_group
number
|
Specifies the NFAS group. The NFAS group number range is from 0 to 31.
|
iua
as-name
|
(Optional) Configures the ISDN User Adaptation Layer (IUA) application server (AS) name.
|
rlm-group
number
|
(Optional) Specifies the Redundant Link Manager (RLM) group and releases the ISDN PRI signaling channel. The RLM group number
range is from 0 to 255.
|
voice-dsp
|
(Optional) Configures an ISDN PRI group for voice applications by using the Digital Signal Processor (DSP).
|
Command Default
No ISDN PRI group is configured. The switch type is automatically set to the National ISDN switch type (primary-ni keyword) when the pri-group timeslots command is configured with the rlm-group keyword.
Command Modes
Controller configuration (config-controller)
Command History
Release
|
Modification
|
11.0
|
This command was introduced.
|
11.3
|
This command was enhanced to support NFAS.
|
12.0(2)T
|
This command was implemented on the Cisco MC3810 multiservice concentrator.
|
12.0(7)XK
|
This command was implemented on the Cisco 2600 and Cisco 3600 series routers.
|
12.1(2)T
|
The modifications in Cisco IOS Release 12.0(7)XK were integrated into Cisco IOS Release 12.1(2)T.
|
12.2(8)B
|
This command was modified with the rlm-group subkeyword to support the release of the ISDN PRI signaling channels.
|
12.2(15)T
|
The modifications in Cisco IOS Release 12.2(8)B were integrated into Cisco IOS Release 12.2(15)T.
|
12.4(16)b
|
This command was modified to ensure that the NFAS primary interface is configured before the NFAS backup or NFAS none interfaces
are configured.
|
12.4(24)T
|
Support was extended to provide backup functionality for the NFAS interface in MGCP backhaul mode. With this support, if the
primary interface fails, the backup can become active and calls can be maintained.
|
15.1(3)T
|
This command was modified. The voice-dsp keyword was added.
|
Usage Guidelines
The pri-group command supports the use of DS0 time slots for
Signaling System 7 (SS7) links, and, therefore, enables the coexistence of SS7 links and PRI voice and data bearer channels
on the same T1 or E1 span. In these configurations, the command applies to voice applications.
In SS7-enabled Voice over IP (VoIP) configurations when an RLM group is configured, High-Level Data Link Control (HDLC) resources
allocated for ISDN signaling on a digital subscriber line (DSL) interface are released and the signaling slot is converted
to a bearer channel (B24). The D channel will be running on IP. The chosen D-channel time slot can still be used by a B channel
by using the isdn rlm-group interface configuration command to configure the NFAS groups.
NFAS allows a single D channel to control multiple PRI interfaces. Use of a single D channel to control multiple PRI interfaces
frees one B channel on each interface to carry other traffic. A backup D channel can also be configured for use when the primary
NFAS D channel fails. When a backup D channel is configured, any hard system failure causes a switchover to the backup D channel
and currently connected calls remain connected.
NFAS is supported only with a channelized T1 controller and, as a result, must be ISDN PRI capable. When the channelized T1
controllers are configured for ISDN PRI, only the NFAS primary D channel must be configured; its configuration is distributed
to all members of the associated NFAS group. Any configuration changes made to the primary D channel will be propagated to
all NFAS group members. The primary D-channel interface is the only interface shown after the configuration is written to
memory.
The channelized T1 controllers on the router must also be configured for ISDN. The router must connect to either an AT&T 4ESS,
Northern Telecom DMS-100 or DMS-250 switch type, or a National ISDN switch type.
The ISDN switch must be provisioned for NFAS. The primary and backup D channels should be configured on separate T1 controllers.
The primary, backup, and B-channel members on the respective controllers should have the same configuration as that of the
router and ISDN switch. The interface ID assigned to the controllers must match that of the ISDN switch.
You can disable a specified channel or an entire PRI interface, thereby taking it out of service or placing it into one of
the other states that is passed in to the switch using the isdn service command.
In the event that a controller belonging to an NFAS group is shut down, all active calls on the controller that is shut down
will be cleared (regardless of whether the controller is set to primary, backup, or none), and one of the following events
will occur:
-
If the controller that is shut down is configured as the primary and no backup is configured, all active calls on the group
are cleared.
-
If the controller that is shut down is configured as the primary, and the active (In service) D channel is the primary and
a backup is configured, then the active D channel changes to the backup controller.
-
If the controller that is shut down is configured as the primary, and the active D channel is the backup, then the active
D channel remains as the backup controller.
-
If the controller that is shut down is configured as the backup, and the active D channel is the backup, then the active D
channel changes to the primary controller.
The expected behavior in NFAS when an ISDN D channel (serial interface) is shut down is that ISDN Layer 2 should go down but
keep ISDN Layer 1 up, and that the entire interface will go down after the amount of seconds specified for timer T309.
Note
|
The active D -channel changeover between primary and backup controllers happens only when one of the link fails and not when
the link comes up. The T309 timer is triggered when the changeover takes place.
|
Note
|
You must first configure the NFAS primary D channel before configuring the NFAS backup or NFAS none interfaces. If this order
is not followed, this message is displayed:
NFAS backup and NFAS none interfaces are not allowed to be configured without primary. First configure primary D channel.
To remove the NFAS primary D channel after the NFAS backup or NFAS none interfaces are configured, you must remove the NFAS
backup or NFAS none interfaces first, and then remove the NFAS primary D channel.
|
The voice-dsp keyword is available only on 1-Port and 2-Port HWIC on ISR-G2 (Cisco 2911, Cisco 2921, Cisco 2951, Cisco 3925, Cisco 3925E,
Cisco 3945, and Cisco 3945E). This keyword is not available on controller T1 0/1/0 on Voice/WAN(VWIC) interface card.
Examples
The following example shows how to configure a T1 controller 1/0 for PRI and for the NFAS primary D channel. This primary
D channel controls all the B channels in NFAS group 1.
controller t1 1/0
framing esf
linecode b8zs
pri-group timeslots 1-24 nfas_d primary nfas_int 0 nfas_group 1
The following example shows how to configure an ISDN PRI on T1 slot 1, port 0, and configure voice and data bearer capability
on time slots 2 through 6:
isdn switch-type primary-4ess
controller t1 1/0
framing esf
linecode b8zs
pri-group timeslots 2-6
The following example shows how to configure a standard ISDN PRI interface:
! Standard PRI configuration:
controller t1 1
pri-group timeslots 1-23 nfas_d primary nfas_int 0 nfas_group 0
exit
! Standard ISDN serial configuration:
interface serial1:23
! Set ISDN parameters:
isdn T309 4000
exit
The following example shows how to configure a dedicated T1 link for SS7-enabled VoIP:
controller T1 1
pri-group timeslots 1-23 nfas_d primary nfas_int 0 nfas_group 0
exit
! In a dedicated configuration, we assume the 24th timeslot will be used by ISDN.
! Serial interface 0:23 is created for configuring ISDN parameters.
interface Serial:24
! The D channel is on the RLM.
isdn rlm 0
isdn T309 4000
exit
The following example shows how to configure a shared T1 link for SS7-enabled VoIP. The rlm-group 0 portion of the pri-group timeslots command releases the ISDN PRI signaling channel.
controller T1 1
pri-group timeslots 1-3 nfas_d primary nfas_int 0 nfas_group 0 rlm-group 0
channel group 23 timeslot 24
end
! D-channel interface is created for configuration of ISDN parameters:
interface Dchannel1
isdn T309 4000
end
The following example shows how to configure T1 controller 0/2/1 for a PRI with the voice applications option:
Router(config)#controller T1 0/2/1
Router(config-controller)#pri-group timeslots 1-24
Router(config-controller)#pri-group timeslots 1-24 voice-dsp