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Community Member

ISDN: Strange behaviour

Hi all,

anyone seen something like this before:

This is the router we are using as voice gatway:

Cisco Router 2801

IOS: c2801-advipservicesk9-mz.124-24.T2

2 FastEthernet interfaces
2 ISDN Basic Rate interfaces     <----------- Two ISDN lines
1 terminal line
1 Virtual Private Network (VPN) Module
2 Voice FXS interfaces
1 DSP, 8 Voice resources
1 cisco Internal Service Module(s)
   Cisco Unity Express 7.1.4 in slot 0

And this is our very basic setup:

interface BRI0/0/0
no ip address
isdn switch-type basic-net3
isdn overlap-receiving
isdn point-to-point-setup
isdn incoming-voice voice
isdn static-tei 0
!
interface BRI0/0/1
no ip address
isdn switch-type basic-net3
isdn overlap-receiving
isdn point-to-point-setup
isdn incoming-voice voice
isdn static-tei 0

And now the mystery:

If we make an incoming call we will see it on both BRI interfaces simultaneously:

Jun 15 12:28:10: ISDN BR0/0/0 Q931: RX <- SETUP pd = 8  callref = 0x3D   <-------- BRI0/0/0
        Sending Complete
        Bearer Capability i = 0x8090A3
                Standard = CCITT
                Transfer Capability = Speech
                Transfer Mode = Circuit
                Transfer Rate = 64 kbit/s
        Channel ID i = 0x89
                Exclusive, B1
        Calling Party Number i = 0x1081, 'xxxxxxxxx3'
                Plan:Unknown, Type:International
        Called Party Number i = 0x81, '5124'
                Plan:ISDN, Type:Unknown
        High Layer Compat i = 0x9181
Jun 15 12:28:10: ISDN BR0/0/1 Q931: RX <- SETUP pd = 8  callref = 0x3D    <-------- BRI0/0/1
        Sending Complete
        Bearer Capability i = 0x8090A3
                Standard = CCITT
                Transfer Capability = Speech
                Transfer Mode = Circuit
                Transfer Rate = 64 kbit/s
        Channel ID i = 0x89
                Exclusive, B1
        Calling Party Number i = 0x1081, 'xxxxxxxxx3'
                Plan:Unknown, Type:International
        Called Party Number i = 0x81, '5124'
                Plan:ISDN, Type:Unknown
        High Layer Compat i = 0x9181
Jun 15 12:28:10: ISDN BR0/0/0 Q931: TX -> CALL_PROC pd = 8  callref = 0xBD
        Channel ID i = 0x89
                Exclusive, B1
Jun 15 12:28:10: ISDN BR0/0/1 Q931: TX -> CALL_PROC pd = 8  callref = 0xBD
        Channel ID i = 0x89
                Exclusive, B1
Jun 15 12:28:10: ISDN BR0/0/0 Q931: TX -> ALERTING pd = 8  callref = 0xBD
Jun 15 12:28:10: ISDN BR0/0/1 Q931: TX -> ALERTING pd = 8  callref = 0xBD
Jun 15 12:28:14: ISDN BR0/0/0 Q931: TX -> CONNECT pd = 8  callref = 0xBD
        Channel ID i = 0x89
                Exclusive, B1
Jun 15 12:28:15: ISDN BR0/0/0 Q931: RX <- RELEASE pd = 8  callref = 0x3D
        Cause i = 0x87A9 - Temporary failure
Jun 15 12:28:15: ISDN BR0/0/1 Q931: RX <- RELEASE pd = 8  callref = 0x3D
        Cause i = 0x87A9 - Temporary failure
Jun 15 12:28:15: ISDN BR0/0/1 Q931: TX -> RELEASE_COMP pd = 8  callref = 0xBD
Jun 15 12:28:16: ISDN BR0/0/0 Q931: TX -> RELEASE_COMP pd = 8  callref = 0xBD
Jun 15 12:28:16: ISDN BR0/0/0 **ERROR**: L2_AdvanceVA: TX_ack_queue empty     <------- Error: The call is disconnected
Jun 15 12:28:16: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BR0/0/0, TEI 0 changed to down
Jun 15 12:28:16: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BR0/0/1, TEI 0 changed to down
Jun 15 12:28:16: ISDN BR0/0/0 Q931: Ux_DLRelInd: DL_REL_IND received from L2
Jun 15 12:28:16: ISDN BR0/0/1 Q931: Ux_DLRelInd: DL_REL_IND received from L2
Jun 15 12:28:18: %ISDN-6-LAYER2UP: Layer 2 for Interface BR0/0/1, TEI 0 changed to up
Jun 15 12:28:20: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BR0/0/1, TEI 0 changed to down
Jun 15 12:28:20: ISDN BR0/0/1 Q931: Ux_DLRelInd: DL_REL_IND received from L2
Jun 15 12:28:32: %ISDN-6-LAYER2UP: Layer 2 for Interface BR0/0/0, TEI 0 changed to up
Jun 15 12:28:32: %ISDN-6-LAYER2UP: Layer 2 for Interface BR0/0/1, TEI 0 changed to up

Strange, isn't it?

Has anyone seen somthin similar?

Is it possible that the Telco switch has a configuration problem?

Many thanks,

Michael

1 ACCEPTED SOLUTION

Accepted Solutions
Super Bronze

Re: ISDN: Strange behaviour

Hi

ISDN2 NTEs typically have two ports.

It looks to me like someone has helpfully connected both ports on the router to both ports on the NTE.

You get 2 channels per port, and 2 channels per ISDN2 circuit, so there's no benefit to doing this. Shut down one port and it will probably work better; then check over the cabling.

If you have two BRI circuits, connect one to each port on the router.

If you have one two-channel BRI, then connect it to a single port.

Regards

Aaron

Please rate helpful posts...

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
5 REPLIES
Super Bronze

Re: ISDN: Strange behaviour

Hi

ISDN2 NTEs typically have two ports.

It looks to me like someone has helpfully connected both ports on the router to both ports on the NTE.

You get 2 channels per port, and 2 channels per ISDN2 circuit, so there's no benefit to doing this. Shut down one port and it will probably work better; then check over the cabling.

If you have two BRI circuits, connect one to each port on the router.

If you have one two-channel BRI, then connect it to a single port.

Regards

Aaron

Please rate helpful posts...

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
Community Member

Re: ISDN: Strange behaviour

Hi Aaron,

thank you for your reply.

We should have two ISDN circuites - at least that is what we ordered (so we can have 4 phone calls simultaniously).

I will have someone to check the cabeling. It's not impossible that someone did a big mistake.

I will keep you up to date.

PS: If I do a shutdown on one interface we can have incoming and outgoing phone calls (although we can have only 2 calls simultaniously)

Thank you for your hint,

Michael

Super Bronze

Re: ISDN: Strange behaviour

Hi

No problem, let us know how you get on.

Aaron

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
Community Member

Re: ISDN: Strange behaviour

Hi Aaron,

you are right! It was a cabling issue.... on site is a NTE with 5 Ports labeled 1 1 3 4 5

Port 1 and 1 use the same bus - who would have thought this? :-)

Thankys for your help.

Super Bronze

Re: ISDN: Strange behaviour

Hi Michael

Glad to hear it's fixed :-)

Aaron

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
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