ASA 5505 LCP terminated: loosing connection every so often

Question

hi,
i'm a little lost with interpreting the following debug messages of an ASA 5505 running "asa724-k8.bin".
I'm loosing the connection every so often after 20-45 Minutes:
%ASA-3-403503:PPPoE:PPP link down:
%ASA-3-403503:PPPoE:PPP link down:Peer Terminated
%ASA-3-403503:PPPoE:PPP link down:
%ASA-3-403503:PPPoE:PPP link down:LCP down
Debugs are attached.
thanks
colin

Answer 1

Hi Colin,
To me the PPPoE debug is a bit of a distraction.
It would be wonderful just to see the PPP debug and not a PPPOE PADI etc.. but that's just my preference :-)
If the Service provider is sending PPP LCP echo request, these act almost like a keepalive to verify the PPP link from the PPPoE access concentrator to the client is up and running. If the ASA doesn't respond, the Service providers access concentrator 'thinks' ah this link is down.
The PPPoE access comncentrator send another LCP echo request and the client should send a echo reply.
Usually in a PPP scenario, both ends send LCP echo requests and expect to see LCP echo replies. As both ends of a PPP link want to know if they are sending packets to a real end point, and that this end point is still up and running.
Or if the Service provider doesn't see the LCP echo reply it will be patient and resent a LCP echo request. But if it still doesn't get a response to a echo request, maybe as a result of congestion over the PPPoE interface and Echo replies getting dumped, the service provider will send a PPP LCP terminate request.
It does this as it has to assume that the link is down between the Access concentrator and the ASA PPPoE client, but it send the LCP terminate request so if the remote end of the link is really up, it will have an option to restart ppp negotiation again and bring up the PPPoE link. This i believe what you are seeing.
The ASA should then start to initaite a PPPoE session again. You will keep on seeing;
%ASA-3-403503:PPPoE:PPP link down:
%ASA-3-403503:PPPoE:PPP link down:Peer Terminated
%ASA-3-403503:PPPoE:PPP link down:
%ASA-3-403503:PPPoE:PPP link down:LCP down
As the Service provider is not seeing an appropriate response to it sending LCP echo requests.
The ASA should be responding to LCP echo requests with LCP echo reply, worthwhile checking this in a debug. (LCP echo requests and replied are very different to ICMP echo requests and echo replied)
The problem could be caused by LCP echo-replies being lost due to congestion.
Again, would be wonderful to see how often you are receiving LCP echo-requests from the service provider and the responses.
Interesting to see a wireshark or ethereal capture of only PPP LCP negotiation and LCP packets. To really see where the problem is.
Sorry not much help without seeing a packet capture..
regards Dave