[c-nsp] L2TP DISCONNECT caused by LCP mismatch

[ahmad fadly]

Thanks oli for the reply

I have tried to replace lcp renegotiation in the
vpdn-group into lcp renegotiation always, going after
that... I reset the LT2P tunnel, then I started to
dial again, the result showed it still have the same
debug output. Eventhough the LCP is completely
negotiated betweeen LNS and LAC after a long
negotiation.


The configuration :

!
vpdn-group 1
! Default L2TP VPDN group
 description End L2TP tunnel StarOne Volume
 accept-dialin
  protocol l2tp
  virtual-template 5
 local name LNS at HOME
 lcp renegotiation always
 l2tp tunnel password 0 imz
 ip mtu adjust
!

Attached is the completely debug output


fadly


--- "Oliver Boehmer (oboehmer)" <oboehmer at cisco.com>
wrote:

> ahmad fadly <> wrote on Thursday, June 19, 2008 8:27
> AM:
> 
> > Hi,
> > 
> > I'm currently setting up L2TP between LNS and
> PDSN,
> > when I dial to the PDSN the dial time sometimes
> takes
> > a long time to be connected. I debug ppp
> negotiation
> > and debug vpdn l2x-events, they show that the LCP
> > negotiation is having very long time negotiation
> but
> > sometimes is not. The message shows to be like
> this,
> > ppp807 LCP: Discarding: CP_CONFACK does not match
> > CP_CONFREQ.
> 
> Hmm.. the LNS sends:
> 
> > 22:43:57: ppp807 LCP: O CONFREQ [Stopped] id 1 len
> 14
> > 22:43:57: ppp807 LCP:    AuthProto PAP
> (0x0304C023)
> > 22:43:57: ppp807 LCP:    MagicNumber
> > 0x08814572(0x050608814572)
> 
> and the client replies
> 
> > 22:43:57: ppp807 LCP: I CONFACK [ACKsent] id 3 len
> 18
> > 22:43:57: ppp807 LCP:    ACCM 0x00000000
> (0x020600000000)
> 
> > 22:43:57: ppp807 LCP:    AuthProto PAP
> (0x0304C023)
> > 22:43:57: ppp807 LCP:    PFC (0x0702)
> > 22:43:57: ppp807 LCP:    ACFC (0x0802)
> 
> The client would be violating RFC1661 by ACK'ing
> options which haven't
> been requested, but looking at the ID (id 3) it
> seems that this ACK is
> from the CONFREQ sent by the LAC? I ignore the
> possibility of the client
> being completely broken ;-)
> It looks like some LCP negotation problem on the
> LAC. Is LCP completely
> negotiated on the LAC?
> 
> You've enabled "lcp renegotiation on-mismatch" in
> the vpdn-group. Can
> you try removing this or changing it to "lcp
> renegotiation always" (you
> need to re-establish the L2TP tunnel in order for
> the new settings to
> take effect, i.e. clear the l2tp tunnel after the
> change)?
> 
> 	oli
>