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Table Of Contents
Packet Mode Services on D Channel
Information About Packet Mode Services on D Channel
ITU Q.931 Packet Mode Procedures
Benefits of the Packet Mode Services on D Channel Feature
How to Enable Packet Mode Services on D Channel Feature
Enabling Packet Mode Services on D Channel Feature
Configuration Examples for Packet Mode Services on D Channel
Enable Packet Mode Services on D Channel: Example
Feature Information for Packet Mode Services on D Channel
Packet Mode Services on D Channel
First Published: February 27, 2006Last Updated: February 27, 2006The Packet Mode Services on D Channel feature allows Japanese and European telephone switches to query Cisco routers for the availability of packet mode services on the ISDN D channel, in compliance with International Telecommunication Union (ITU) specification Q.931.
Finding Feature Information in This Module
Your Cisco IOS software release may not support all of the features documented in this module. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for Packet Mode Services on D Channel" section and the "Related Documents" section.
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
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Information About Packet Mode Services on D Channel
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Information About Packet Mode Services on D Channel
To configure the Packet Mode Services on D Channel feature, you should understand the following concepts:
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ITU Q.931 Packet Mode Procedures
Cisco IOS software prior to Cisco IOS Release 12.4(6)T provides support for X.25 over the ISDN D channel using the ITU Q.931 service access point identifier (SAPI) value 16 procedures for call setup required by some switches, but this support does not adhere to the standard for packet mode communications for the ISDN D channel using SAPI value 0 procedures for call setup. The Packet Mode Services on D Channel feature complies with the SAPI value 0 connection procedures, and allows Japanese and some European telephone switch types to query Cisco routers for availability of packet mode services on the ISDN D channel, in compliance with ITU specification Q.931, section 6, which describes packet mode communications for the ISDN D channel.
Although regular X.25 and ISDN configuration commands may be sufficient to enable this feature, the Japanese NTT ISDN switch types expect the same terminal endpoint identifier (TEI) to be shared. By default, Cisco gateways will try to use two different TEIs and expect the switch to establish an X.25 link on the TEI that responds. The Japanese NTT switch does not follow this procedure and expects the Cisco router to share the same TEI. Cisco recommends that deployments interworking with the Japanese NTT switch type use the isdn x25 dchannel interface configuration command with the optional q931-broadcast keyword to enable sharing of the TEI and avoid interworking problems. The optional q931-broadcast keyword can also be used in configurations for other switch types such as the European NET3 that require sharing of the TEIs. The optional q931-broadcast keyword is supported only on the ISDN BRI interface user side of the network.
Benefits of the Packet Mode Services on D Channel Feature
The benefit of installing the Packet Mode Services on D Channel feature is compliance with the Q.931 SAPI value 0 procedures for call setup, which allows Cisco routers to interoperate with Japanese and European (NTT and NET3) telephone switches.
How to Enable Packet Mode Services on D Channel Feature
This section contains the following procedure:
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Enabling Packet Mode Services on D Channel Feature
The Japanese NTT (and some European NET3) ISDN switch types expect the same TEI to be shared across the ISDN interface. By default, Cisco gateways will try to use two different TEIs and expect the switch to establish an X.25 link on the TEI that responds. The NTT and NET3 switches do not follow this procedure and expect the Cisco router to share the same TEI. When this feature is installed as part of Cisco IOS Release 12.4(6)T software, deployments interworking with the Japanese NTT switch type can use the Packet Mode Services on D Channel feature to enable sharing of the TEI and avoid interworking issues.
Following are the prerequisites, restrictions, and steps you need to follow on deployments interworking with the Japanese NTT switch type to enable sharing of the TEI and avoid interworking incompatibilities. These steps ensure that Q.931 SAPI value 0 procedures are enabled, and that X.25 calls can be accepted correctly on the ISDN D channel.
Prerequisites
Timer T320 must be disabled for this feature to work.
Restrictions
This feature is supported only on incoming calls, and only on BRI interfaces. All outgoing calls use SAPI value 16 procedures (X.25 on the D channel).
SUMMARY STEPS
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DETAILED STEPS
Configuration Examples for Packet Mode Services on D Channel
This section provides the following example:
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Enable Packet Mode Services on D Channel: Example
The following is a typical configuration that enables SAPI 0 procedures that accept X.25 calls on the ISDN D channel, on ISDN BRI interface 0:
isdn switch-type basic-nttx25 routing!interface BRI0no ip addressno ip directed-broadcastdialer load-threshold 1 eitherisdn switch-type basic-net3isdn x25 dchannel q931-broadcast!interface BRI0:0ip address 192.168.1.1 255.255.255.252no ip directed-broadcastno ip mroute-cachex25 address 12503372501x25 htc 2x25 map ip 192.168.1.2 2231146!The debug isdn q931, debug isdn events detail, and debug isdn mgmnt EXEC commands have been enhanced for Cisco IOS Release 12.4(6)T, to provide information about accepting X.25 calls on the ISDN D channel. For purpose of example, bold type in the following output indicates reports seen when the isdn x25 dchannel interface configuration command with the optional q931-broadcast keyword is enabled:
Router# debug isdn q931*Sep 28 12:34:29.739: ISDN BR1/1 Q931: RX <- SETUP pd = 8 callref = 0x5C (re-assembled)Bearer Capability i = 0x88C0C2E6Standard = CCITTTransfer Capability = Unrestricted DigitalTransfer Mode = PacketTransfer Rate = Packet - not specifiedUser Info L2 Protocol = Recommendation Q921/I.441User Info L3 Protocol = Recommendation X.25, Packet LayerChannel ID i = 0x8CExclusive, No B-channelInformation Rate i = 0x8888Packet Layer Binary Params i = 0x80Packet Layer Window Size i = 0x8282Packet Size i = 0x8888Calling Party Number i = 0x0083, '144014384106'Plan:Unknown, Type:UnknownUser-User i = 0x02CC000000Router# debug isdn events detail*Sep 28 12:34:29.747: ISDN BR1/1 EVENTd: isdn_host_packet_mode_events: Host packet call received call id 0xBRouter# debug isdn mgmnt*Jun 8 22:38:56.535: ISDN BR0 Q921: User TX -> IDREQ ri=29609 ai=127*Jun 8 22:38:56.595: ISDN BR0 Q921: User RX <- IDASSN ri=29609 ai=86*Jun 8 22:38:56.595: ISDN BR0 SERROR: L2_Go: at bailout DLCB is NULLL2: sapi 63 tei 127 ces 0 ev 0x3*Jun 8 22:38:56.595: ISDN BR0 MGMNT: LM_MDL_UI_DATA_IND: message 2 ri 29609 ai86 switch type 9*Jun 8 22:38:56.595: ISDN BR0 MGMNT: LM_MDL_UI_DATA_IND: OVERLAP REQUEST: ces 9using lmtr tei 85 tei 85Additional References
The following sections provide references related to the Packet Mode Services on D Channel feature.
Related Documents
ISDN and BRI switch configuration procedures
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X.25 routing configuration
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Standards
ITU-T Q.931
ISDN USER-NETWORK INTERFACE LAYER 3 SPECIFICATION FOR BASIC CALL CONTROL
MIBs
None
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use the Cisco MIB Locator found at the following URL:
RFCs
Technical Assistance
Command Reference
This section documents the following modified command:
isdn x25 dchannel
To create a configurable interface for X.25 traffic over the ISDN D channel, use the isdn x25 dchannel command in interface configuration mode. To remove the interface, use the no form of this command.
isdn x25 dchannel [q931-broadcast]
no isdn x25 dchannel [q931-broadcast]
Syntax Description
q931-broadcast
(Optional) Enables a gateway to share the same terminal endpoint identifier (TEI) for sending X.25 Set Asynchronous Balanced Mode Extended (SABME) and ITU Q.931 packet mode responses.
Defaults
Command is disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
This command creates a new, configurable interface, which can be specified as interface brix:0 in commands, where x is the original BRI interface number. For example, on a Cisco 4500 router with an MBRI, if the isdn x25 dchannel command is configured on interface BRI 5, the new interface is bri5:0 and can be used for configuring the other parameters for X.25 over the D channel. These parameters include the addresses and the map statements. To display the new interface, use the more system:running-config command.
The optional q931-broadcast keyword is supported only on the ISDN BRI interface user side. Although regular X.25 and ISDN configuration commands may be sufficient to enable this feature, the Japanese NTT ISDN switch types expect the same TEI to be shared. By default, Cisco gateways will try to use two different TEIs and expect the switch to establish an X.25 link on the TEI that responds. The Japanese NTT switch does not follow this procedure and expects the Cisco router to share the same TEI. Cisco recommends that deployments interworking with the Japanese NTT switch type use the optional q931-broadcast keyword to enable sharing of the TEI and avoid interworking incompatibilities. The optional q931-broadcast keyword can also be used in configurations for other switch types such as the European NET3 that require sharing of the TEIs.
You can verify the X.25 call accept procedure using the debug isdn events, debug isdn command with the optional mgmnt keyword, and debug isdn q931 EXEC commands.
Examples
The following example creates BRI interface 0 and configures it for X.25 over the ISDN D channel. This example uses dynamic TEIs, not a static TEI.
interface bri1isdn x25 dchannelinterface bri1:0ip address 10.1.1.2 255.255.255.0x25 address 31107000000100x25 htc 1x25 suppress-calling-addressx25 facility windowsize 2 2x25 facility packetsize 256 256x25 facility throughput 9600 9600x25 map ip 10.1.1.3 31107000000200x25 map ip 10.1.1.4 31107000000800The following is a typical configuration that enables SAPI 0 procedures that accept X.25 calls on the ISDN D channel, on ISDN BRI interface 0:
isdn switch-type basic-nttx25 routing!interface BRI0no ip addressno ip directed-broadcastdialer load-threshold 1 eitherisdn switch-type basic-net3isdn x25 dchannel q931-broadcast!interface BRI0:0ip address 192.168.1.1 255.255.255.252no ip directed-broadcastno ip mroute-cachex25 address 12503372501x25 htc 2x25 map ip 192.168.1.2 2231146!Related Commands
Feature Information for Packet Mode Services on D Channel
Table 1 lists the release history for this feature.
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. 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.
Note
Table 1 Feature Information for Packet Mode Services on D Channel
Packet Mode Services on D Channel
12.4(6)T
This feature allows Japanese and European telephone switches to query Cisco routers for the availability of packet mode services on the ISDN D channel, in compliance with International Telecommunication Union (ITU) specification Q.931.
The following sections provide information about this feature:
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The following command was modified by this feature: isdn x25 dchannel.
Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.
© 2006 Cisco Systems, Inc. All rights reserved.
