Table Of Contents
Information About ISDN PRI-SLT
ISDN Assumptions About the Location of the PRI D Channel
ISDN Commands Supported by ISDN PRI-SLT
The D-Channel Interface and Cisco SS7 Interconnect for Voice Gateways
Release the PRI Signaling Time Slot
Configuration Examples for ISDN PRI-SLT
SS7-Enabled VoIP PRI Shared T1 Configuration Example
ISDN PRI-SLT
The ISDN PRI-SLT feature allows you to release the ISDN PRI signaling time slot for Redundant Link Manager (RLM) configurations, and for Signaling System 7 (SS7) applications in integrated Signaling Link Terminal (SLT) configurations. This feature supports the use of DS0 time slots for SS7 links, and allows the coexistence of SS7 links and PRI voice and data bearer channels on the same T1 or E1 controller span.
Feature Specifications for ISDN PRI-SLT
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.
Contents
•Information About ISDN PRI-SLT
•How to Configure ISDN PRI-SLT
•Configuration Examples for ISDN PRI-SLT
Information About ISDN PRI-SLT
To configure the ISDN PRI-SLT feature, you need to understand the following concepts:
•ISDN Assumptions About the Location of the PRI D Channel
•ISDN Commands Supported by ISDN PRI-SLT
•The D-Channel Interface and Cisco SS7 Interconnect for Voice Gateways
ISDN Assumptions About the Location of the PRI D Channel
ISDN PRI is designed to carry large numbers of incoming ISDN calls at large central site locations. ISDN PRI has 23 B channels running at 64 kbps each and a shared 64-kbps D channel that carries signaling traffic. ISDN PRI is often referred to as "23 B + D" (North America and Japan) or "30 B + D" (Europe and the rest of the world).
Figure 1 shows how many B channels and D channels are assigned to the ISDN media types.
Figure 1
BRI and PRI Channel Assignments
Figure 2 shows the logical contents of a Cisco ISDN PRI interface used in a standard T1 network configuration.
Figure 2 Logical Relationship of ISDN PRI Components for T1
The software assumed that the 24th (or 16th for E1) slot in the controller is reserved for D-channel signaling. However, in environments that require SS7-enabled Voice over IP (VoIP) configurations, some applications needed to share all time slots in a PRI group but were not allowed to use the 24th (or 16th) time slot. The ISDN PRI-SLT Cisco IOS Release 12.2(8)B feature, and specifically, the rlm-group subkeyword introduced in the pri-group timeslots controller configuration command as part of this feature, releases the signaling time slots, thereby supporting SS7 applications in VoIP configurations.
ISDN Commands Supported by ISDN PRI-SLT
The following ISDN commands are supported on the D-channel interface to configure ISDN data in SS7-enabled VoIP environments. Refer to the Cisco IOS Dial Technologies Command Reference, Release 12.2 and the Cisco IOS Voice, Video, and Fax Command Reference, Release 12.2 for full command syntax and usage guidelines.
The D-Channel Interface and Cisco SS7 Interconnect for Voice Gateways
A new interface, D-channel, is introduced with the ISDN PRI-SLT feature for use specifically in VoIP applications, such as an SS7 Interconnect Voice Gateway that requires release of ISDN signaling time slots for RLM configurations.
A Cisco SLT is a key component of the Cisco SS7 Interconnect for Voice Gateways feature. In the Cisco SS7 Interconnect for Voice Gateways environment, the D channel will be on Ethernet, and the time slots on an E1 and T1 controller can be shared by other applications such as SS7.
How to Configure ISDN PRI-SLT
This section contains the following tasks. Each task is identified as either required or optional.
•Release the PRI Signaling Time Slot (required)
•Verify ISDN PRI-SLT (optional)
Release the PRI Signaling Time Slot
To release the ISDN PRI signaling time slot for environments that require SS7-enabled VoIP applications to share all available time slots in a PRI group, use the following commands:
SUMMARY STEPS
1. enable
2. configure {terminal | memory | network}
3. controller {t1 | e1} controller-number
4. pri-group timeslots timeslot-range [nfas_d {backup | none | primary {nfas_int number | nfas_group number | rlm-group number}} | service]
5. channel-group channel-number timeslots range [speed {48 | 56 | 64}]
6. exit
7. interface Dchannel interface-number
8. isdn command parameter (use the commands listed in Table 1 on page 4 to configure the ISDN interface)
9. exit
DETAILED STEPS
Verify ISDN PRI-SLT
To verify that the ISDN PRI-SLT feature is working, perform the following optional steps:
SUMMARY STEPS
1. enable
2. show isdn status
DETAILED STEPS
Troubleshooting Tips
Use the commands described in Table 1 to troubleshoot the ISDN PRI-SLT feature.
Configuration Examples for ISDN PRI-SLT
This section provides the following configuration examples to match the configuration tasks in the previous sections:
•SS7-Enabled VoIP PRI Shared T1 Configuration Example
SS7-Enabled VoIP PRI Shared T1 Configuration Example
The following example shows how to release the ISDN PRI signaling time slot for RLM configurations on a shared T1 link:
controller T1 1pri-group time slots 1-3 nfas_d primary nfas_int 0 nfas_group 0 rlm-group 0channel group 23 timeslot 24exit! New Dchannel interface is created for configuration of ISDN parameters:interface Dchannel1isdn T309 4000exitVerify ISDN PRI-SLT Example
The following example output from the show isdn status EXEC command includes a report about D-channel and RLM group status:
Router# show isdn statusGlobal ISDN Switchtype = primary-niISDN Dchannel0 interface rlm-group = 1Transport Link Status:ACTIVEdsl 0, interface ISDN Switchtype = primary-ni : Primary D channel of nfas group 0Layer 1 Status:DEACTIVATEDLayer 2 Status:TEI = 0, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHEDLayer 3 Status:0 Active Layer 3 Call(s)Active dsl 0 CCBs = 0The Free Channel Mask: 0x80000000Number of L2 Discards = 0, L2 Session ID = 43ISDN Dchannel1 interfaceTransport Link Status : Not Applicabledsl 1, interface ISDN Switchtype = primary-ni : Group member of nfas group 0Layer 1 Status:DEACTIVATEDLayer 2 Status: Not ApplicableLayer 3 Status:0 Active Layer 3 Call(s)Active dsl 1 CCBs = 0The Free Channel Mask: 0x80000000Number of L2 Discards = 0, L2 Session ID = 0ISDN Serial2:15 interfacedsl 2, interface ISDN Switchtype = primary-ni : Primary D channel of nfas group 1Layer 1 Status:DEACTIVATEDLayer 2 Status:TEI = 0, Ces = 1, SAPI = 0, State = TEI_ASSIGNEDLayer 3 Status:0 Active Layer 3 Call(s)Active dsl 2 CCBs = 0The Free Channel Mask: 0x0Number of L2 Discards = 0, L2 Session ID = 0ISDN Serial3:15 interfacedsl 3, interface ISDN Switchtype = primary-ni : Group member of nfas group 1Layer 1 Status:ACTIVATINGLayer 2 Status: Not ApplicableLayer 3 Status:0 Active Layer 3 Call(s)Active dsl 3 CCBs = 0The Free Channel Mask: 0x0Number of L2 Discards = 0, L2 Session ID = 0Total Allocated ISDN CCBs = 0Additional References
For additional information related to ISDN PRI-SLT, refer to the following references:
•MIBs
•RFCs
Related Documents
Related Topic Document TitleDial ISDN commands
Cisco IOS Dial Technologies Command Reference, Release 12.2
ISDN PRI
Cisco IOS Dial Technologies Configuration Guide, Release 12.2; refer to "Configuring ISDN PRI" in the "Signaling Configuration" part
Voice ISDN commands
Cisco IOS Voice, Video, and Fax Command Reference, Release 12.2
Voice ISDN interfaces
Cisco IOS Voice, Video, and Fax Configuration Guide, Release 12.2; refer to the chapter "Configuring ISDN Interfaces for Voice"
Standards
MIBs
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
http://tools.cisco.com/ITDIT/MIBS/servlet/index
If Cisco MIB Locator does not support the MIB information that you need, you can also obtain a list of supported MIBs and download MIBs from the Cisco MIBs page at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
To access Cisco MIB Locator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL:
RFCs
Technical Assistance
Command Reference
This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.2 command reference publications.
New Command
Modified Commands
interface Dchannel
To specify an ISDN D-channel interface and enter interface configuration mode, use the interface Dchannel command in global configuration mode.
interface Dchannel interface-number
Syntax Description
Defaults
No D-channel interface is specified.
Command Modes
Global configuration
Command History
Release Modification12.2(8)B
This command was introduced.
12.2(15)T
This command was integrated into Cisco IOS Release 12.2(15)T.
Usage Guidelines
This command is used specifically in Voice over IP (VoIP) applications that require release of the ISDN PRI signaling time slot for RLM configurations.
Examples
The following example configures a D-channel interface for a Signaling System 7 (SS7)-enabled shared T1 link:
controller T1 1pri-group timeslots 1-3 nfas_d primary nfas_int 0 nfas_group 0 rlm-group 0channel group 23 timeslot 24end! D-channel interface is created for configuration of ISDN parameters:interface Dchannel1isdn T309 4000endRelated Commands
pri-group timeslots
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 | none | primary {nfas_int number | nfas_group number | rlm-group number}} | service]
no pri-group timeslots timeslot-range [nfas_d {backup | none | primary {nfas_int number | nfas_group number | rlm-group number}} | service]
Syntax Description
Defaults
There is no ISDN PRI group 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 subkeyword.
Command Modes
Controller configuration
Command History
Usage Guidelines
The pri-group command supports the use of DS0 time slots for Signaling System 7 (SS7) links, and therefore the coexistence of SS7 links and PRI voice and data bearer channels on the same T1 or E1 span. The command applies to configuration of 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). D channel will be running on IP. The chosen D-channel time slot can still be used as a B channel by using the isdn rlm-group interface configuration command to configure the NFAS groups.
Examples
The following example specifies ISDN PRI on T1 slot 1, port 0, and configures voice and data bearer capability on time slots 2 through 6:
isdn switch-type primary-4esscontroller t1 1/0framing esflinecode b8zspri-group timeslots 2-6The following example configures a standard ISDN PRI interface:
! Standard PRI configuration:controller t1 1pri-group time slots 1-23 nfas_d primary nfas_int 0 nfas_group 0exit! Standard ISDN serial configuration:interface serial1:23! Set ISDN parameters:isdn T309 4000exitThe following example configures a dedicated T1 link for SS7-enabled VoIP:
controller T1 1pri-group time slots 1-23 nfas_d primary nfas_int 0 nfas_group 0exit! 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 0isdn T309 4000exitThe following example configures 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 1pri-group timeslots 1-3 nfas_d primary nfas_int 0 nfas_group 0 rlm-group 0channel group 23 timeslot 24end! D-channel interface is created for configuration of ISDN parameters:interface Dchannel1isdn T309 4000endRelated Commands
show isdn
To display the information about memory, Layer 2 and Layer 3 timers, and the status of PRI channels, use the show isdn command in EXEC mode.
show isdn {active [dsl | serial-number] | history [dsl | serial-number] | memory | service [dsl | serial-number] | status [dsl | serial-number] | timers [dsl | serial-number]}
Syntax Description
Command Modes
EXEC
Command History
Examples
The following sample output from the show isdn status command shows a report about D-channel and RLM group status for RLM configurations, and applications like Signaling System 7 (SS7) in integrated Signaling Link Terminal (SLT) configurations:
Router# show isdn statusGlobal ISDN Switchtype = primary-niISDN Dchannel0 interface rlm-group = 1Transport Link Status:ACTIVEdsl 0, interface ISDN Switchtype = primary-ni : Primary D channel of nfas group 0Layer 1 Status:DEACTIVATEDLayer 2 Status:TEI = 0, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHEDLayer 3 Status:0 Active Layer 3 Call(s)Active dsl 0 CCBs = 0The Free Channel Mask: 0x80000000Number of L2 Discards = 0, L2 Session ID = 43ISDN Dchannel1 interfaceTransport Link Status : Not Applicabledsl 1, interface ISDN Switchtype = primary-ni : Group member of nfas group 0Layer 1 Status:DEACTIVATEDLayer 2 Status: Not ApplicableLayer 3 Status:0 Active Layer 3 Call(s)Active dsl 1 CCBs = 0The Free Channel Mask: 0x80000000Number of L2 Discards = 0, L2 Session ID = 0ISDN Serial2:15 interfacedsl 2, interface ISDN Switchtype = primary-ni : Primary D channel of nfas group 1Layer 1 Status:DEACTIVATEDLayer 2 Status:TEI = 0, Ces = 1, SAPI = 0, State = TEI_ASSIGNEDLayer 3 Status:0 Active Layer 3 Call(s)Active dsl 2 CCBs = 0The Free Channel Mask: 0x0Number of L2 Discards = 0, L2 Session ID = 0ISDN Serial3:15 interfacedsl 3, interface ISDN Switchtype = primary-ni : Group member of nfas group 1Layer 1 Status:ACTIVATINGLayer 2 Status: Not ApplicableLayer 3 Status:0 Active Layer 3 Call(s)Active dsl 3 CCBs = 0The Free Channel Mask: 0x0Number of L2 Discards = 0, L2 Session ID = 0Total Allocated ISDN CCBs = 0Table 2 describes the significant fields shown in the display.