Topology: PC--LAC (MA5200)--LNS (AR28)--Radius Server
Problem: AR28 serves as LNS, and L2TP dial-up authentication uses Radius. During dial-up of PC, MA5200 and AR28 could set up tunnel, but PPP authentication fails, and session cannot be set up.
*0.78656390 JBVPDN RDS/8/DEBUG:Send attribute list:
*0.78656390 JBVPDN RDS/8/DEBUG:
[1 User-name ]  [firstname.lastname@example.org]
[2 Password ]  [65C2A5E41BEF58B1CCA3B11CF61D219A]
[4 NAS-IP-Address ] [6 ] [188.8.131.52]
[32 NAS-Identifier ] [8 ] [JBVPDN]
[5 NAS-Port ] [6 ] 
[61 NAS-Port-Type ] [6 ] 
[6 Service-Type ] [6 ] 
[7 Framed-Protocol ] [6 ] 
*0.78656390 JBVPDN RDS/8/DEBUG:Send: IP=[184.108.40.206], UserIndex=, ID=, RetryTimes=, Code=, Length=
*0.78665390 JBVPDN RDS/8/DEBUG:RADIUS Server No Response
1. AR28 could ping to the address of RADIUS Server, indicating that the link from AR28 to RADIUS Server is straightforward. DEBUG helps ascertain that AR28 has reported the username and password to RADIUS Server.
2. The problem could be solved by configuring correct key for AR28.
AR28 has sent the username and password to RADIUS Server, but the server does not respond. This is because AR28 is not configured with key for RADIUS and accounting.