Cisco Cisco IOS Software Release 12.4(6)T
Packet Mode Services on D Channel
Information About Packet Mode Services on D Channel
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Cisco IOS Release 12.4(6)T
Information About Packet Mode Services on D Channel
To configure the Packet Mode Services on D Channel feature, you should understand the following
concepts:
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.
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.
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.
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
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