Cisco IOS Dial Technologies Configuration Guide, Release 12.2SR
ISDN BCAC and Round-Robin Channel Selection Enhancements
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ISDN BCAC and Round-Robin Channel Selection Enhancements

Table Of Contents

ISDN BCAC and Round-Robin Channel Selection Enhancements

Contents

Prerequisites for ISDN BCAC Enhancements

Information About the ISDN BCAC and Round-Robin Channel Selection Enhancements

BCAC Enhancements

Round-Robin Selection Scheme for ISDN B Channels

Logging of ISDN Events

Additional ISDN Switch Types Supported for Network Emulation

How to Configure the ISDN Enhancements

Configuring BCAC Service Audit Triggers

Examples

Configuring BCAC Service State Triggers

Examples

Configuring BCAC Message Retransmission

Examples

Configuring B-Channel Selection Order

Examples

Configuring ISDN Syslog Messages

Examples

Configuration Examples for ISDN BCAC and Round-Robin Channel Selection Enhancements

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

Glossary


ISDN BCAC and Round-Robin Channel Selection Enhancements


The ISDN BCAC and Round-Robin Channel Selection Enhancements feature allows more dynamic control of the ISDN B channels by providing additional B-Channel Availability Control (BCAC) functionality for configuring message signaling, and an enhanced channel selection scheme that adds round-robin configuration to the existing ascending and descending channel selection schemes already available.

Feature Specifications for the ISDN BCAC Enhancements

Feature History
 
Release
Modification

12.3(1)

This feature was introduced.

Supported Platforms

Cisco AS5300, Cisco AS5350, Cisco AS5400, Cisco AS5800, Cisco AS5850, Cisco 2600 series, Cisco 3640, Cisco 3660


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

Prerequisites for ISDN BCAC Enhancements

Information About the ISDN BCAC and Round-Robin Channel Selection Enhancements

How to Configure the ISDN Enhancements

Configuration Examples for ISDN BCAC and Round-Robin Channel Selection Enhancements

Additional References

Command Reference

Prerequisites for ISDN BCAC Enhancements

You need to need to be familiar with the BCAC service message signaling procedure and configuring ISDN PRI before configuring the commands described in this document. See the "Standards" section for a list of references.

Information About the ISDN BCAC and Round-Robin Channel Selection Enhancements

The following functionality is introduced in the ISDN BCAC and Round-Robin Channel Selection Enhancements:

BCAC Enhancements

Round-Robin Selection Scheme for ISDN B Channels

Logging of ISDN Events

Additional ISDN Switch Types Supported for Network Emulation

BCAC Enhancements

BCAC is a service message signaling procedure used to control the availability of ISDN B channels. BCAC provides a coordinated capability between both ends of a PRI to simultaneously preclude selection of specified B channels for outgoing calls, and reject calls (if channel negotiation is employed, calls may go on another channel) for those same channels. The basic BCAC functionality for the handling of SERV and SERV ACK messages already exists on Cisco routers. In Cisco IOS Release 12.3(1), the software has been enhanced with the following BCAC functionality:

Processing of SERV and SERV ACK messages. Even though these messages are already handled in the Cisco IOS software, their processing has been enhanced to more closely align with the behavior described in the standards.

Provides a mechanism to allow the retransmission of SERV messages.

Handles SERV message collision cases.

Provides service status audits for various audit triggers.

Provides an option that when set triggers the exchange of service messages on all channels of the interface when the router is rebooted and when the signaling link comes up.

Provides a mechanism so that if there is a flood of service messages that need to be sent, the service messages can be throttled to avoid losing them.

Initializes B-channel service status upon provisioning.

Round-Robin Selection Scheme for ISDN B Channels

ISDN enhancements introduced in Cisco IOS Release 12.3(1) enable you to select a B channel on a PRI or a Non-Facility Associated Signaling (NFAS) interface in a round-robin fashion. This option is in addition to the ascending or descending channel selection schemes already available.

Logging of ISDN Events

ISDN enhancements introduced in Cisco IOS Release 12.3(1) support syslog logging of the following ISDN events:

ISDN Layer 2 Up and Down events at severity 3.

ISDN SERV, SERV ACK, Restart, Restart Ack, and Status Enq messages at severity 4.

ISDN SERV status audit messages for various triggers at different severities.

Additional ISDN Switch Types Supported for Network Emulation

ISDN enhancements introduced in Cisco IOS Release 12.3(1) extend network emulation capability to the Lucent 4ESS, 5ESS, and Nortel DMS-100 ISDN switch types. These switch types can be configured as network, but no additional changes were made and not all network-side features are supported.

How to Configure the ISDN Enhancements

This section contains the following procedures. Each procedure is optional and depends upon the settings required for your network.

Configuring BCAC Service Audit Triggers (optional)

Configuring BCAC Service State Triggers (optional)

Configuring BCAC Message Retransmission (optional)

Configuring B-Channel Selection Order (optional)

Configuring ISDN Syslog Messages (optional)

Configuring BCAC Service Audit Triggers

Perform this task to configure BCAC service audit triggers:

SUMMARY STEPS

1. enable

2. configure terminal

3. interface serial port:channel

4. isdn bcac service audit

5. isdn bcac service audit trigger number

6. isdn bcac service audit interface

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

interface serial port:channel

Example:

Router(config)# interface serial 2:23

Enters interface configuration mode on the specified serial port and channel.

Step 4 

isdn bcac service audit

Example:

Router(config-if)# isdn bcac service audit

Enables BCAC service audits.

Step 5 

isdn bcac service audit trigger number

Example:

Router(config-if)# isdn bcac service audit trigger 2

Enables individual BCAC service audit triggers.

Step 6 

isdn bcac service audit interface

Example:

Router(config-if)# isdn bcac service audit interface

Specifies that BCAC service audits need to be triggered on the entire interface.

Examples

The following example shows how to enable service audits on serial interface 4:23:

interface serial 4:23
 isdn bcac service audit

The following example shows how to disable service trigger 4 on serial interface 4:23:

interface serial 4:23
 no isdn bcac service audit trigger 4

See the command page for the isdn bcac service audit trigger command for a list of the triggers that are set.

The following example shows how to configure service audits on the entire interface:

interface serial 4:23
 isdn bcac service audit interface

Configuring BCAC Service State Triggers

Perform this task to configure BCAC service state triggers:

SUMMARY STEPS

1. enable

2. configure terminal

3. interface serial port:channel

4. isdn bcac service update provision

5. isdn bcac service update linkup

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

interface serial port:channel

Example:

Router(config)# interface serial 2:23

Enters interface configuration mode on the specified serial port and channel.

Step 4 

isdn bcac service update provision

Example:

Router(config-if)# isdn bcac service update provision

Enables BCAC service status functionality for provisioning the B channels.

Step 5 

isdn bcac service update linkup

Example:

Router(config-if)# isdn bcac service update linkup

Triggers updates of the BCAC service states between peer nodes through exchange of SERV and SERV ACK messages.

Examples

The following example shows how to enable the SERV status message for provisioning the B channels on serial interface 4:23:

interface serial 4:23
 isdn bcac service update provision

The following example shows how to trigger service state updates on serial interface 4:23:

interface serial 4:23

 isdn bcac service update linkup

Configuring BCAC Message Retransmission

Perform this task to configure retransmission of BCAC service messages:

SUMMARY STEPS

1. enable

2. configure terminal

3. interface serial port:channel

4. isdn bcac service timer timer-value

5. isdn bcac service retry max retries

6. isdn bcac service retry in-serv-on-fail

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

interface serial port:channel

Example:

Router(config)# interface serial 2:23

Enters interface configuration mode on the specified serial port and channel.

Step 4 

isdn bcac service timer timer-value

Example:

Router(config-if)# isdn bcac service timer 600

Changes the value of the BCAC T3M1 or T323 service message timer.

Valid range is from 500 to 120000 ms, and the default is 120000 ms.

Step 5 

isdn bcac service retry max retries

Example:

Router(config-if)# isdn bcac service retry max retries

Specifies the maximum number of times a BCAC service message can be retransmitted when unacknowledged.

The default is 2 attempts, and you can enter a number from 0 to 127.

Step 6 

isdn bcac service retry in-serv-on-fail

Example:

Router(config-if)# isdn bcac service retry in-serv-on-fail

Specifies that the BCAC service state of the channel needs to be changed to In-Service, because no acknowledgment message was received.

Examples

The following example shows how to configure an option whereby, on service message exchange failure, the service state of the concerned channel or channels will be set to In-Service:

interface serial 2:23
 isdn bcac service retry in-serv-on-fail

The following example shows how to set the maximum number of service message retransmissions on serial interface 2:23 to 50:

interface serial 2:23
 isdn bcac service retry max 50

The following example shows how to change the service timers to 600 ms on serial interface 2:23:

interface serial 2:23
 isdn bcac service timer 600

Configuring B-Channel Selection Order

Perform this task to configure selection order of the ISDN B channels:

SUMMARY STEPS

1. enable

2. configure terminal

3. interface serial port:channel

4. isdn bchan-number-order {ascending | descending} [round-robin]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

interface serial port:channel

Example:

Router(config)# interface serial 2:23

Enters interface configuration mode on the specified serial port and channel.

Step 4 

isdn bchan-number-order {ascending | descending} [round-robin]

Example:

Router(config-if)# isdn bchan-number-order ascending round-robin

Configures an ISDN PRI interface to make outgoing call selection in ascending or descending order.

The optional round-robin keyword adds round-robin selection functionality to the selection order.

Examples

The following example configures the outgoing B channel selection order on a PRI interface to be round-robin in ascending order:

interface serial 5:10 
 isdn bchan-number-order ascending round-robin

Configuring ISDN Syslog Messages

Perform this task to configure logging of ISDN syslog messages:

SUMMARY STEPS

1. enable

2. configure terminal

3. isdn logging

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

isdn logging

Example:

Router(config)# isdn logging

Enables logging of ISDN syslog messages.

Examples

The following example shows how to configure ISDN syslog logging:

isdn logging

Configuration Examples for ISDN BCAC and Round-Robin Channel Selection Enhancements

See the examples following each task in the preceding sections, for ideas about how the ISDN CBAC enhancements and other new ISDN features can be introduced into your network.

Additional References

For additional information related to the ISDN enhancements, see the following sections:

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Related Documents

Related Topic
Document Title

ISDN PRI configuration

Refer to the "Configuring ISDN PRI" chapter in the "Signaling Configuration" part of the Cisco IOS Dial Technologies Configuration Guide, Release 12.3.

ISDN PRI configuration commands

Cisco IOS Dial Technologies Command Reference, Release 12.3.

ISDN PRI configuration for voice, video, and fax

Refer to the chapter "Configuring ISDN Interfaces for Voice " in the Cisco IOS Voice, Video, and Fax Configuration Guide, Release 12.3.

ISDN PRI voice, video, and fax configuration commands

Cisco IOS Voice, Video, and Fax Command Reference, Release 12.3


Standards

Standards 1
Title

AT&T PRI

Technical Report 41459-AT&T ISDN Primary Rate Interface and Special Application Specification; "User Network Interface Description," 1999.

National ISDN Council (NIC) PRI

SR (Special Report)-NWT-002343-ISDN Primary Rate Interface Generic Guidelines for Customer Premises Equipment, June 1993.

SR-3887-National ISDN Primary Rate Interface Customer Premises Equipment Generic Guidelines, 1996.

Nortel PRI

NIS (Network Interface Specification)-A211-1-DMS100 ISDN Primary Rate Network User Interface, 1993.

1 Not all supported standards are listed.


MIBs

MIBs
MIBs Link

None

To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL:

http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml


RFCs

RFCs
Title

None


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Command Reference

The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS Dial Technologies Command Reference at http://www.cisco.com/en/US/docs/ios/dial/command/reference/dia_book.html. For information about all Cisco IOS commands, go to the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List.

New Commands

isdn bcac service audit

isdn bcac service audit interface

isdn bcac service audit trigger

isdn bcac service retry in-serv-on-fail

isdn bcac service retry max

isdn bcac service timer

isdn bcac service update linkup

isdn bcac service update provision

isdn logging

Modified Commands

isdn bchan-number-order

isdn protocol-emulate (dial)

Glossary

PBX—private branch exchange.

RESTART—restart message.

RESTART ACK—restart acknowledge message.

STATUS ENQ—status enquiry message.

SERV—service message.

SERV ACK—service acknowledge message.


Note Refer to the Internetworking Terms and Acronyms for terms not included in this glossary.