ISDN problem. CHAP success but then immediate disconnect.

[mattbauer]

Hi all

It's been a long time since Ive used ISDN and Im wondering if there is something basic that Ive overlooked.

Below is some debug output of the disconnection problem:

BR0/0/0:1 LCP: State is Open

BR0/0/0:1 PPP: Phase is AUTHENTICATING, by both

BR0/0/0:1 CHAP: O CHALLENGE id 32 len 34 from "local-router"

BR0/0/0:1 PPP: I pkt type 0xC223, datagramsize 33 link[ppp]

BR0/0/0:1 CHAP: I CHALLENGE id 203 len 29 from "remote-router"

BR0/0/0:1 CHAP: Using hostname from interface CHAP

BR0/0/0:1 CHAP: Using password from interface CHAP

BR0/0/0:1 CHAP: O RESPONSE id 203 len 34 from "local-router"

BR0/0/0:1 PPP: I pkt type 0xC223, datagramsize 8 link[ppp]

BR0/0/0:1 CHAP: I SUCCESS id 203 len 4

BR0/0/0:1 PPP: I pkt type 0xC021, datagramsize 8 link[ppp]

BR0/0/0:1 LCP: I TERMREQ [Open] id 91 len 4

BR0/0/0:1 LCP: O TERMACK [Open] id 91 len 4

BR0/0/0:1 PPP: Sending Acct Event[Down] id[4873]

BR0/0/0:1 PPP: Phase is TERMINATING

So it seems that authentication is ok, but then (I guess) I recieve a termination request (I TERMREQ) which I respond to (O TERMACK) thus closing the connection.

The question is, why do I recieve this termination request?

Unfortunately asking the remote end is not giving me any clues. They are a government department and will not give me any information other than "This is a standard config at our end that has been working with others for 5 years". They will not give me a recommended config or even look at logs etc. So before I go back to them again, I want make sure that there's nothing missing from my end.

Here's my config:

interface BRI0/0/0

bandwidth 64

no ip address

ip accounting output-packets

encapsulation ppp

dialer pool-member 1

isdn switch-type ntt

peer default ip address dhcp

no keepalive

!

interface Dialer1

bandwidth 64

ip address dhcp

encapsulation ppp

dialer pool 1

dialer idle-timeout 600

dialer string 12345678

dialer-group 1

peer default ip address dhcp

no keepalive

ppp authentication chap

ppp chap hostname hostname

ppp chap password password

ip route 192.168.0.0 255.255.255.0 Dialer1

dialer-list 1 protocol ip permit

Any ideas?

Thanks

Matt

[mattbauer]

guys, deb ppp neg and deb ppp auth *were* on. The text document I attached earlier called isdn-debug.txt has all of those debugs on. Furthermore, it says: "CHAP: I SUCCESS id 255 len 4" which presumably means CHAP authentication was successful.

Re: DHCP, Ive been told by the other end that I will definately be getting my IP address via DHCP. It's their standard config.

[paolo bevilacqua]

Hi,

Actually "RX <- DISCONNECT" means the local router has received a disconnect request, consequently the termination is by the remote router, not the local one. This is also confirmed by:

BR0/0/0:1 LCP: I TERMREQ [Open] id 91 len 4

I guess they are asking for the debugs taken on the remote router.

[dphills18]

i had this very issue not too long ago. i goofed up and had the wrong network set on my concentrator. verify the network and wildcard mask on your concentrator.

hope that helps.

[mattbauer]

ok, so I think it quite clear that my end config looks pretty tight and, as suspected, the remote router is initiating the disconnect for reasons unknown.

So until I can squeeze more information out of the other side, Im stuck.

Ill post an update if/when I find a solution.

Thanks for the information so far everyone.

Matt

[paolo bevilacqua]

Hi,

I guess your router is calling, right ?

So please try "ppp authentication chap callin", or remove "ppp authentication" altogether.

Also please re-enable keepalives that is normal operation.