I am experiencing an inconsistent authentication issue with PPP CHAP on a 1721 with 2x WIC-1ADSL, PPPoATM and MLPPP. IOS is 12.4(7).
After a great deal of debugging etc. I am confident that the issue lies with the CHAP auth against my ISP. If the connection drops, I usually have to shut/no shut the dialer interface anywhere from 2 to 25 times before I get a CHAP SUCCESS message back; else the authentication just sits in a loop. *** SEE ATTACHMENT 'CHAP_1.txt' ***
This auth loop will go on indefinitely, and also occurs if the router has been power-cycled/reloaded- I will have to shut/no shut the dialer many times before I successfully auth and negotiate an IP- its a game of chance!
As you can see, there are never any CHAP FAILURE messages so auth is not being denied. After numerous shut/no shuts we finally get a SUCCESS back and things look good. *** SEE ATTACHMENT 'CHAP_2_SUCCESS.txt' ***
The router always talks to the correct ISP LNS, "g.dsl". I have spoken with my ISP who have no explanation; they see no failed auth's in their RADIUS logs.
Relivent portions of my conf are attached *** SEE ATTACHMENT 'running-config_1.txt' ***
Please can someone assist me with this? Please do not hesiate to request additional information.
Many thanks in advance.