ISDN PRI unique problem

nbhandarkar · ‎10-16-2004

Hi,

My problem is with an ISDN PRI. Whenever I fire an ISDN line to any remote site.....It always connects to the remote site using the 30th channel instead of taking random channel. I didn't find any prob with config.......have anyone faced this kind of problem???

The essential part of config is as below:

controller E1 1/0

framing NO-CRC4

channel-group 0 timeslots 31

channel-group 1 timeslots 1

channel-group 2 timeslots 2

channel-group 3 timeslots 3

channel-group 4 timeslots 4

channel-group 5 timeslots 5

channel-group 6 timeslots 6

channel-group 7 timeslots 7

channel-group 8 timeslots 8

channel-group 9 timeslots 9

channel-group 10 timeslots 10

channel-group 11 timeslots 11

channel-group 12 timeslots 12

channel-group 13 timeslots 13

channel-group 14 timeslots 14

channel-group 15 timeslots 15

channel-group 16 timeslots 16

channel-group 17 timeslots 17

channel-group 18 timeslots 18

channel-group 19 timeslots 19

channel-group 20 timeslots 20

channel-group 21 timeslots 21

channel-group 22 timeslots 22

channel-group 23 timeslots 23

channel-group 24 timeslots 24

channel-group 25 timeslots 25

channel-group 26 timeslots 26

channel-group 27 timeslots 27

channel-group 28 timeslots 28

channel-group 29 timeslots 29

channel-group 30 timeslots 30

!

interface Serial1/0:15

description "isdn pri no. is XXXX8905"

no ip address

encapsulation ppp

dialer pool-member 1

isdn switch-type primary-net5

no cdp enable

ppp authentication chap

ppp multilink

!

interface Dialer11

description ISDN BACKUP

ip unnumbered Serial1/1:3

encapsulation ppp

dialer pool 1

dialer remote-name core2

dialer idle-timeout 1800

dialer string XXXXXXXX

dialer-group 1

ppp authentication chap

dialer-list 1 protocol ip permit

thanks.

Kevin Dorrell · ‎10-16-2004

This behaviour is normal.

The convention is that the subscriber starts at the top of the range, i.e. channel 30, and works downwards. For outgoing calls it will always use the highest available channel number.

The exchange, on the other hand, starts at the lowest channel, and works upwards. It always takes the lowest available channel number. You will always see the incoming calls on low channel numbers,

That way, the probability of a call collision is reduced to the absolute minium, and then can only happen on the last available channel.

X.25 normally works in the same way: DTE starts at the top channel, and DCE starts at the bottom.

Why do you feel this is a problem? There must be a clue in the way you have tried to pin down the channel groups. Normally you let all the channels in a single pool, and the dialer uses whichever on it wants. For outgoing calls it just picks a channel, starting at 30, and uses it. For incoming calls, the channel gets bound to the dialer by the CHAP remote name.

That leaves us with the command I don't understand, the ip unnumbered Serial1/1:3. What are you trying to achieve there? Is S1/1 a fractional E1 or something?

Kevin Dorrell

Luxembourg

marinos_g · ‎10-17-2004

Kevin,

How do you do this BOLD typing... ???

UNDERLINED ????

ITALIC ???

:)

Thank you

Marinos