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New Member

8 interfaces BRI, 2 Group-Async and 2 dialers.

I have a router 3640 with one card 8 interfaces BRI and one card with 18 analogical modems.

I have 2 kind of remote access users :

- the first kind will arrive on the 1st 6 interfaces BRI.

- the second kind will arrive on the last 2 interfaces BRI.

The remote access users will connecte to 3640 either by analogical modem or by isdn modem, so :

I need to configure one dialer and one asynchrone group for each of my 2 kind of users.

For example :

- int Group-Async1 and int dialer 10 : for users of 1st kind (calls from BRI 1/0 to BRI 1/5)


- int Group-Async2 and int dialer 20 : for users of 2nd kind (calls from BRI 1/6 to BRI 1/7)

If you have any typical configuration of this sort, you will be very kind to post it on the forum.

Is-it possible to have only call-back for some users (username bob callback-dialstring "" password 0 bob) belonging to the first kind of the remote access users ?

Any suggestions is appreaciated.

Thanks in advance


Re: 8 interfaces BRI, 2 Group-Async and 2 dialers.

When you are configuring one dialer for all users, you are using the old mode of linking dialers to lines. This is done by assigning lines to dialer-rotary groups.

dialer rotary-group 1 corresponds with dialer 1 and so on.

This implies that you should use rotary-group 10 on lines BRI 1/0 to BRI 1/5 and 20 for BRI 1/6 to BRI 1/7.

Call-back is done on a per-user basis and is not directly related to the called number. Hope this helps a bit. Feel free to post any further question but I am off now so this should do it for the moment.



New Member

Re: 8 interfaces BRI, 2 Group-Async and 2 dialers.

Thank a lot for your answer.

I am agree with you for isdn calls.

Two notes:

- About analogical calls, according to you, how to associate the int Group-Async1 to the interfaces BRI 1/0 to BRI 1/5 and int Group-Async2 to the interfaces BRI 1/6 and 1/7 ?

on all int BRI, I put "isdn incoming-voice modem". But with this commande I can not associate a number of a int group-async. How can i do this association ?

- For you, it is not a problem for callback to have 2 int dialer. ? One of my colleague told me that callback does not work when configuration have 2 int dialer... !!!

Best regards.


Re: 8 interfaces BRI, 2 Group-Async and 2 dialers.

As far as I know it work like this:

Group Async 1 corresponds to rotary-group 1, just like dialer1.

Use the interface command: group-range to assign modem lines to the async groups. I suppose that you have a DMM? Then do a sh lin to see the lines that are assigned to the modems. On my systems, these are the lines in the range 65 to 88, a 24 modem module. The actual number may vary depending on the slot configuration. You will identify them quickly enough I presume.

Here is my group-asyc:

interface Group-Async1

ip unnumbered Loopback1

no ip directed-broadcast

encapsulation ppp

ip tcp header-compression passive

no logging event link-status

async mode interactive

no peer default ip address

no fair-queue

no cdp enable

ppp authentication pap

group-range 65 88


About the dialers I am not sure. There might be an issue. Try configuring the callback-group as inout, and the other as incoming.

This is my line-configuration for the modems:

line 65 88

session-timeout 60

exec-timeout 60 0

autoselect during-login

autoselect ppp

modem InOut

modem autoconfigure discovery

rotary 1

transport preferred telnet

transport input all

stopbits 1

flowcontrol hardware




Cisco Employee

Re: 8 interfaces BRI, 2 Group-Async and 2 dialers.

You need to have Digital Modems (Mica modem with part number NM-xDM) on 3640 to accept a analog modem calls over isdn bri lines. If you have analog modems, 3640 can't terminate the analog calls over bri lines on 3640 routers.

Following url for more sample config on that

Problem will still be there as there is no way to force 3600 routers to pick the modems for incoming calls from certain groups of modems. In other words modem pooling is not supported on 3600 routers.

Once you have digital modems in 3640, with 8 bri lines, the config will look like following

config for bri 1/0 to 1/5 will be the same and same for 1/6 to 1/7

int bri 1/0

dialer rotary-group 1

isdn incoming-voice modem


int bri 1/6

dialer rotary-group 2

isdn incoming-voice modem


int dialer 1

(for 1st kind users)

int dialer 2

(For 2nd kind users)


interface groupe-async 1

group-range x y

New Member

Re: 8 interfaces BRI, 2 Group-Async and 2 dialers.

I tried the configuration that lgijssel wrote me : "rotary 1" in line 65 88 but such my lab, it doest not work. I did some tests : the 3640 uses always ALL these asyn interfaces by round robin.

So, as you said, Tepatel, it seems to me that it is not possible.

So, I have change my idea. I would like to configure the 3640 such as it processes the callback to the SAME BRI interface on which it had received the incoming call. By default, it do round robin on all 8 BRI interfaces.

I posted the new question on the forum.

May be you can help me ?

Thanks a lot in advance.