Second ISDN BRI link won't come up on WAN link

[Mark_Matthias]

I have two routers connected via ISDN.

When I type "show ISDN active", I only see one phone call, no matter what I do to generate tons of traffic.

(I can bring up the second link on other pairs of my routers using the extended ping command and bumping the packet size to 1500 or more).

When debugging, I see the following message on the called router " BR1/1 DDR: has 2 ongoing call(s), maximum allowed call(s) 2 on pool 2, exceeded m

ax ".

I tried everything listed on this web link

http://www.cisco.com/en/US/tech/tk801/tk379/technologies_tech_note09186a0080094b7a.shtml Document ID 22480.

I have a second ISDN line at one of the two locations. I thought is might be a bad ISDN line so, I toggled over to the second ISDN line and it also failed with the same indication that both lines are in use. In reality, they are not.

My general configuration is:

interface BRI1/1

description ISDN to rtr using D0

no ip address

encapsulation ppp

dialer pool-member 1

isdn switch-type basic-ni

isdn spid1 12345678900101 4567890

isdn spid2 12345678980101 4567898

no fair-queue

ppp multilink

!

interface Dialer0

description ISDN to rtr_2520 using BRI1/0

ip address 10.23.23.2 255.255.0.0

encapsulation ppp

dialer pool 1

dialer remote-name RTR_2520

dialer idle-timeout 2147483

dialer string xxxxxxxxxxx

dialer string xxxxxxxxxxx

dialer load-threshold 5 outbound

dialer-group 1

no fair-queue

ppp multilink

Does anyone have any other ideas?

Thanks

[Richard Burts]

Mark

I do not see any ppp authentication in the config that you posted. I am not clear whether it is really missing or whether you just did not think that it was worth posting. If it is missing then I suggest that you configure it.

If you do debug dialer on both routers before any dialing activity I suspect that you will see router1 place a call to router2 and then see router2 place a call to router1. And then both channels ARE in use.

I have seen situations where ISDN was configured without authentication. router1 places a call to router2. router2 wants to send a response and opens a connection (because without authentication it does not know that it already has an open connection to router1). I suspect that is what is happening in your situation.

So try it with authentication configured. If authentication is already configured, then give us a more complete view into the configuration.

HTH

Rick

[Mark_Matthias]

Thanks Rick,

The only changes I made to the configuration prior to posting it relate to ip addresses and SPID numbers.

I'm hesitating before making a change like adding ppp authentication. I've set up over 50 of these and they all work without it except this pair. I'm thinking maybe it's something local to that installation or region (Miami). The installer didn't seem as familiar with ISDN as some. This router's been in place only a month and probably never worked with both B channels.

This Miami pair sends traffic back and forth just fine, but only at 64k.

Am I correct in thinking that if there was an authentication issue, traffic/data would not pass?

When I type "show ISDN active" the list always only shows one active call on either router. So that makes me think the other call may be, as you say, dialing.

I have limitted windows to work on this and am not going to be on site. Is there anything else you might think I could try in addition to authentication at my next window?

Other info: Regarding using one dialer string or two: I get the MAX lines in use error when I use one dialer string (hunt group) or two, so I assume the SPIDs are in a hunt group and I continue testing (or observing)with just the one dialer string.

Thanks,

Mark

[Richard Burts · Accepted solution]

Mark

I am surprised that it works well in other locations without authentication. But you know your network.

I would like to respond to your statement: "Am I correct in thinking that if there was an authentication issue, traffic/data would not pass". It depends on what kind of authentication issue. If no authentication is configured then data can pass. If authentication is configured but one (or both) peers do not authenticate correctly then the connection will be terminated and no data will pass.

If you are working remotely you should still be able to debug dialer and look at which router (or both) are initiating calls. I wonder if debug isdn q931 might give some insight also.

HTH

Rick

[Mark_Matthias]

Thanks Rick,

Adding ppp authentication chap and making sure usernames and passwords were properly matched seemed to clear this up. It's been working properly for several hours.

I appreciate your help.

Mark

[Richard Burts]

Mark

Thanks for posting back to the forum indicating that the problem was resolved (and thanks for the rating). It makes the forum more useful when people can read about a problem and know that a solution was found and see what the solution was.

I encourage you to continue your participation in the forum.

HTH

Rick

[kamal-learn]

hi

do check if the PPP multilink is enabled on the remote router too!!!

HTH