A fast question about crossover E1 cable for ISDN PRI, to connect two PBX via two pri

Asterisk Asterisk Hardware
1

A fast question.
I want to connect two asterisk pbx via isdn PRI(i know there is iax2 and is more fast and simple…but i want to test PRI for knowledge).
I have a doubt about the crossover cable needed
I use this combination


        pin1               pin2         pin3            pin4          pin5            pin6    pin7        pin8
SIDEA   Orange/white       ORANGE       white/green     BLUE          WHITE/BLUE      GREEN   white/brown brown

SIDEB   BLUE               white/blue   white/green     WHITE/ORANGE  ORANGE          GREEN   white/brown brown

for the correct color order i’ve refer to this

https://www.comms-express.com/infozone/wp-content/uploads/2017/01/T568A-and-T568B-wiring-spec-standards.jpg

So pin 1 of sideA is pin4 of SIDEB
and pin2 of sideA is pin5 of SIDEB
pin 4 of sideB is pin1 of sideA
pin 5 of sideB is pin2 of sideA

But in this forum/mailing list an user said

1 – 5
2 – 4
4 – 2
5 – 1

What did you suggest to use?

With my combination I obtain a lot of hdlc errors, span1 down, etc
I also tried a “pre-made” cable from amazon with same results.

2

Probably not going to be a fast question, as I don’t think there is much PRI expertise here, however, have you made sure that one and only one side is providing the timing?

Does some data get through?

1 Like
3

https://help.sangoma.com/community/s/article/How-do-I-make-a-T1-E1-Crossover-cable

1 Like
4

Making the command

pri set debug on I can see some data, but no answer is created.

How I can be sure only one side provide the timing?

5

The cable is ok, I have tested with a Ethernet tester.

6

For timing source I configured on pri_net side

/etc/dahdi/system.conf

# Autogenerated by /usr/sbin/dahdi_genconf on Sun Mar 13 01:37:53 2022
# If you edit this file and execute /usr/sbin/dahdi_genconf again,
# your manual changes will be LOST.
# Dahdi Configuration File
#
# This file is parsed by the Dahdi Configurator, dahdi_cfg
#
# Span 1: WCT1/0 "Digium Wildcard TE110P T1/E1 Card 0" (MASTER) 
span=1,0,0,ccs,hdb3,crc4
# termtype: te
bchan=1-15,17-31
dchan=16
echocanceller=mg2,1-15,17-31

# Global data

loadzone	= it
defaultzone	= it

for cpe_side I configured the same file…


# Autogenerated by /usr/sbin/dahdi_genconf on Thu Mar 31 00:48:03 2022
# If you edit this file and execute /usr/sbin/dahdi_genconf again,
# your manual changes will be LOST.
# Dahdi Configuration File
#
# This file is parsed by the Dahdi Configurator, dahdi_cfg
#
# Span 1: TE2/0/1 "T2XXP (PCI) Card 0 Span 1" 
span=1,1,0,ccs,hdb3,crc4
# termtype: te
bchan=1-15,17-31
dchan=16
echocanceller=mg2,1-15,17-31

# Span 2: TE2/0/2 "T2XXP (PCI) Card 0 Span 2" 
span=2,2,0,ccs,hdb3,crc4
# termtype: te
bchan=32-46,48-62
dchan=47
echocanceller=mg2,32-46,48-62

When I start Asterisk on cpe_side I see


[Mar 31 20:34:13] NOTICE[4773]: chan_dahdi.c:2780 my_handle_dchan_exception: Got DAHDI event: HDLC Bad FCS (8) on D-channel of span 1
[Mar 31 20:34:14]   == Primary D-Channel on span 1 up
[Mar 31 20:34:16] NOTICE[4773]: chan_dahdi.c:2780 my_handle_dchan_exception: Got DAHDI event: HDLC Bad FCS (8) on D-channel of span 1
7

on pri_net side I see


[Mar 31 20:41:26] PRI Span: 1 TEI=0 Got SABME from cpe peer.
[Mar 31 20:41:26] PRI Span: 1 TEI=0 Sending UA
[Mar 31 20:41:26] PRI Span: 1 TEI=0 MDL-ERROR (F): SABME in state 7(Multi-frame established)
[Mar 31 20:41:27] PRI Span: 1 TEI=0 Got SABME from cpe peer.
[Mar 31 20:41:27] PRI Span: 1 TEI=0 Sending UA
[Mar 31 20:41:27] PRI Span: 1 TEI=0 MDL-ERROR (F): SABME in state 7(Multi-frame established)
[Mar 31 20:41:28] PRI Span: 1 TEI=0 Got SABME from cpe peer.
[Mar 31 20:41:28] PRI Span: 1 TEI=0 Sending UA
[Mar 31 20:41:28] PRI Span: 1 TEI=0 MDL-ERROR (F): SABME in state 7(Multi-frame established)
[Mar 31 20:41:29] PRI Span: 1 TEI=0 Got SABME from cpe peer.
[Mar 31 20:41:29] PRI Span: 1 TEI=0 Sending UA
[Mar 31 20:41:29] PRI Span: 1 TEI=0 MDL-ERROR (F): SABME in state 7(Multi-frame established)
[Mar 31 20:41:31] PRI Span: 1 TEI=0 Got SABME from cpe peer.
[Mar 31 20:41:31] PRI Span: 1 TEI=0 Sending UA
[Mar 31 20:41:31] PRI Span: 1 TEI=0 MDL-ERROR (F): SABME in state 7(Multi-frame established)
[Mar 31 20:41:32] PRI Span: 1 TEI=0 Got SABME from cpe peer.
[Mar 31 20:41:32] PRI Span: 1 TEI=0 Sending UA
[Mar 31 20:41:32] PRI Span: 1 TEI=0 MDL-ERROR (F): SABME in state 7(Multi-frame established)
8

It’s been a while but have you configured \etc\asterisk\chan_dahdi.conf on both ends?

9

Of course

[trunkgroups]
[channels]
language=it
context=local
switchtype=euroisdn
signalling=pri_cpe
usecallerid=yes
hidecallerid=no
callwaiting=yes
usecallingpres=yes
callwaitingcallerid=yes
threewaycalling=yes
transfer=yes
canpark=yes
cancallforward=yes
callreturn=yes
context=local
echocancel=yes
channel => 1-15,17-31
echocancelwhenbridged=yes
group=1
callgroup=1
pickupgroup=1
immediate=no
#include /etc/asterisk/dahdi-channels.conf

the other one is identical except for signalling, which is pri_net

10

Really, you should be getting support from the card vendor for this. However, what I’m talking about seems to be appear, somewhere, as syncsrc, although I’m not sure if that is a reflection of hardware settings, rather than something that you can set in software.

I’m not even sure if the PRI hardware supports being the primary clock source. It might be that all you can do is choose which line provides that. Normally PSTN would provide a single clock source for the whole network.

11

Another thing, the card is an old pci card, I put in a pci-express slot
with an adapter, can be this the cause of problems?

12

The patlooptest give errors, is the card damaged?

./patlooptest /dev/dahdi/1 -t 300 -v
Using Timeout of 300 Seconds
Going for it...
Error 1 (loop 0, offset 1, error 1): Unexpected result, Read: 0xff, Expected 0x00.
Error 2 (loop 0, offset 2, error 2): Unexpected result, Read: 0xff, Expected 0x00.
Error 3 (loop 0, offset 3, error 3): Unexpected result, Read: 0xff, Expected 0x00.
Error 4 (loop 0, offset 4, error 4): Unexpected result, Read: 0xff, Expected 0x00.
Error 5 (loop 0, offset 5, error 5): Unexpected result, Read: 0xff, Expected 0x00.
Error 6 (loop 0, offset 6, error 6): Unexpected result, Read: 0xff, Expected 0x00.
Error 7 (loop 0, offset 7, error 7): Unexpected result, Read: 0xff, Expected 0x00.
Error 8 (loop 0, offset 8, error 8): Unexpected result, Read: 0xff, Expected 0x00.
Error 9 (loop 0, offset 9, error 9): Unexpected result, Read: 0xff, Expected 0x00.
Error 10 (loop 0, offset 10, error 10): Unexpected result, Read: 0xff, Expected 0x00.
Error 11 (loop 0, offset 11, error 11): Unexpected result, Read: 0xff, Expected 0x00.
Error 12 (loop 0, offset 12, error 12): Unexpected result, Read: 0xff, Expected 0x00.
13

I have tried in another pc, this time pure pci slot, no adapters, etc.
Same error, probably card is broken

15

The card TE110P works fine also, the problem was the cable (the cable made by me and the two cables which I had buy on stores and working really bad!)
I have buy a Cat5E cable, the plugs and make cable following this perfect video-guide. I have configured the two pri as I did in the first post, I had only to reboot the pri_net machine and…works all.

16

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