|
|
The DMS100 and NI2 switch types have been added to the existing Non-Facility Associated Signaling (NFAS) with D Channel Backup feature.
ISDN NFAS allows a single D channel to control multiple PRI interfaces. A backup D channel can be configured for use when the primary NFAS D channel fails.
Once the channelized T1controllers are configured for ISDN PRI, only the NFAS primary D channel must be configured; its configuration is distributed to all the members of the associated NFAS group.
Use of a single D channel to control multiple PRI interfaces can free one B channel on each interface to carry other traffic.
Any hard failure causes a switchover to the backup D channel and currently connected calls remain connected.
24 B channel interface--A PRI channel group configured to have no NFAS D channel; all its channels are B channels.
NFAS group--A PRI channel group (the group of interfaces) under control of a single D channel. The channel group can include all the ISDN channels on multiple T1 controllers. Cisco IOS supports ten PRI interfaces in an NFAS group with a primary D channel and a backup D channel. Five NFAS groups are supported in a single chassis.
NFAS member--A PRI interface in an NFAS group. For example, an NFAS group might include serial interfaces 1/0:23, 1/1:23, and 2/0:23 if T1 controllers 1/0, 1/1, and 2/0 are configured for NFAS.
non-facility associated signaling (NFAS)--An ISDN service that allows a single D channel to control multiple PRI interfaces. Use of a single D channel to control multiple PRI interfaces can free one B channel on each interface to carry other traffic.
The following restrictions apply to this feature:
| Switch Type | NFAS Type |
|---|---|
| Lucent 4ESS | Custom NFAS |
| Nortel DMS250 | Custom NFAS |
| Nortel DMS100 | Custom NFAS |
| Lucent 5ESS | Custom - Does not support NFAS |
| Lucent 5ESS | NI-2 NFAS |
| AGCS GTD5 | NI-2 NFAS |
| Other Switch Types | NI-2 NFAS |
This feature is supported on these platforms:
The router's channelized T1 controllers must be configured for ISDN, as described in the "Configuring ISDN PRI" section of the "Configuring Channelized E1 and Channelized T1" chapter in the Cisco IOS Release 11.3 Dial Solutions Configuration Guide.
None
To configure NFAS with D channel back up, complete the following task:
You can also disable a channel or interface, if necessary, and monitor NFAS groups and ISDN service. To do so, complete the tasks in the following sections:
This section documents tasks used to configure NFAS with D channel backup. When configuring NFAS, you use an extended version of the ISDN pri-group command to specify the following values for the associated channelized T1 controllers configured for ISDN:
To configure ISDN NFAS, complete the following tasks in controller configuration mode:
| Task | Command |
|---|---|
| On one channelized T1 controller, configure the NFAS primary D channel. | pri-group timeslots 1-24 nfas_d primary nfas_interface number nfas_group number |
| On a different channelized T1 controller, configure the NFAS backup D channel to be used if the primary D channel fails. | pri-group timeslots 1-24 nfas_d backup nfas_interface number nfas_group number |
| On other channelized T1 controllers, configure a 24 B channel interface, if desired. (Optional) | pri-group timeslots 1-24 nfas_d none nfas_interface number nfas_group number |
For an example of configuring three T1 controllers for the NFAS primary D channel, the backup D channel, and 24 B channels, along with the DDR configuration for the PRI interface, see the "NFAS Primary and Backup D Channels Example" section.
When a backup NFAS D channel is configured and the primary NFAS D channel fails, rollover to the backup D channel is automatic and all connected calls stay connected.
If the primary NFAS D channel recovers, the backup NFAS D channel remains active and does not switch over again unless the backup NFAS D channel fails.
You can disable a specified channel or an entire PRI interface, thus taking it out of service or put it into one of the other states that is passed in to the switch. To disable a specific channel or PRI interface, complete one of the following tasks in interface configuration mode:
| Task | Command |
| Take an individual B channel out of service or set it to a different state. | isdn service dsl number b_channel number state state-value |
| Set the entire PRI interface to the specified state. | isdn service dsl number b_channel 0 state state-value |
These are the supported state values:
To monitor NFAS groups, complete the following task in EXEC mode:
| Task | Command |
|---|---|
| Display information about members of an NFAS group. | show isdn nfas group number |
To display information about ISDN channel service states, complete the following task in EXEC mode:
| Task | Command |
|---|---|
| Display information about ISDN channels and the service states. | show isdn service |
This section provides the following configuration examples:
The following example configures ISDN PRI and NFAS on three T1 controllers of a Cisco 7500 series router. The NFAS primary D channel is configured on the 1/0 controller, and the NFAS backup D channel is configured on the 1/1 controller. No NFAS D channel is configured on the 2/0 controller; it is configured for 24 B channels.
Once the NFAS primary D channel is configured, it is the only interface you see and have to configure; DDR configuration for the primary D channel--which is distributed to all B channels--is also included in this example.
isdn switch-type primary-dms100 ! ! NFAS primary D channel on the channelized T1 controller in 1/0 controller t1 1/0 framing esf linecode b8zs pri-group timeslots 1-24 nfas_d primary nfas_interface 0 nfas_group 1 ! ! NFAS backup D channel on the channelized T1 controller in 1/1 controller t1 1/1 framing esf linecode b8zs pri-group timeslots 1-24 nfas_d backup nfas_interface 1 nfas_group 1 ! ! NFAS 24 B channels on the channelized T1 controller in 2/0 controller t1 2/0 framing esf linecode b8zs pri-group timeslots 1-24 nfas_d none nfas_interface 2 nfas_group 1 ! ! NFAS primary D channel interface configuration for PPP and DDR. This ! configuration is distributed to all the B channels in NFAS group 1 on the ! three channelized T1 controllers. ! interface Serial 1/0:23 ip address 1.1.1.2 255.255.255.0 no ip mroute-cache encapsulation ppp dialer map ip 1.1.1.1 name flyboy 567898 dialer map ip 1.1.1.3 name flyboy 101112345678 dialer map ip 1.1.1.4 name flyboy 01112345678 dialer-group 1 no fair-queue no cdp enable ppp authentication chap
The following example reenables the entire PRI interface after it previously had been disabled:
isdn service dsl 0 b-channel 0 state 0
There are no new or modified commands for this feature. Existing commands used to configure this feature are documented in the Cisco IOS Release 11.3 command references.
|
|